AM-6879+TM+11-5820-922-40-1

TM 11-5820-922-40-1

TECHNICAL MANUAL

GENERAL SUPPORT MAINTENANCE MANUAL

A M P L I F I E R - C O N V E R T E R A M - 6 8 7 9 / U R C

( N S N 5 8 2 0 - 0 1 - 0 7 0 - 1 9 5 0 )

HEADQUARTERS, DEPARTMENT OF THE ARMY

1 5 J A N U A R Y 1 9 8 6

TM 11-5820-922-40-1

SAFETY STEPS TO FOLLOW IF SOMEONEIS THE VICTIM OF ELECTRICAL SHOCK

DO NOT TRY TO PULL OR GRAB THE INDIVIDUAL

IF POSSIBLE, TURN OFF THE ELECTRICAL POWER

IF YOU CANNOT TURN OFF THE ELECTRICALPOWER, PULL, PUSH, OR LIFT THE PERSON TOSAFETY USING A WOODEN POLE OR A ROPE ORSOME OTHER INSULATING MATERIAL

SEND FOR HELP AS SOON AS POSSIBLE

AFTER THE INJURED PERSON IS FREE OF

CONTACT WITH THE SOURCE OF ELECTRICALSHOCK, MOVE THE PERSON A SHORT DISTANCEAWAY AND IMMEDIATELY START ARTIFICIALRESUSCITATION

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TM 11-5820-922-40-1

HIGH VOLTAGEis used in the operation of this equipment

DEATH ON CONTACTmay result if personnel fail to observe safety precautions

Never work on electronic equipment unless there is another person nearby who is

familiar with the operation and hazards of the equipment and who is competent in

administering first aid. When the technician is aided by operators, he must warn them about

dangerous areas.

Whenever possible, the power supply to the equipment must be shut off before beginning

work on the equipment. Take part particular care to ground every capacitor likely to hold a

dangerous potential. When working inside the equipment, after the power has been turned off,

always ground every part before touching it.

Be careful not to contact high-voltage connections or 115 volt ac input connections when

installing or operating this equipment.

Whenever the nature of the operation permits, keep one hand away from the equipment

to reduce the hazard of current flowing through the body.

Warning: Do not be misled by the term "low voltage. " Potentials as low as 50 volts may

cause death under adverse conditions.

For Artificial Respiration, refer to FM 21-11:

B

TM 11-5820-922-40-1

SAFETY SUMMARY

The following are general safety precautions that are not related to any specific procedures andtherefore do not appear elsewhere in this publication.These are recommended precautions thatpersonnel must understand and apply during many phases of operation and maintenance.

KEEP AWAY FROM LIVE CIRCUITS

Operating personnel must at all times observe all safety regulations. Unless specifically directed inthis manual, do not replace components or make adjustments inside the equipment with anypower supply turned on. Under certain conditions, dangerous potentials may exist in the powersupplies when the power control is in the off position. To avoid casualties, always remove powerand discharge and ground a circuit before touching it.

DO NOT SERVICE OR ADJUST ALONE

Under no circumstances should any person reach into or enter the enclosure for the purpose ofservicing or adjusting the equipment except in the presence of someone who is capable ofrendering aid.

RESUSCITATION

FIRST AID

Each person engaged in electrical operations will be trained in first aid, particularly in thetechnique of mouth to mouth resuscitation and closed chest heart massage (FM 21-11).

The following warnings appear in this volume, and are repeated here for emphasis.

WARNING

A 3-wire (line, neutral, and safety ground) AC line power connections is required whenoperating the equipment. If a 3-wire safety grounded AC power receptacle is notavailable, a separate ground wire must be installed from the chassis ground to an earthground. Without an adequate ground, the equipment chassis and frame will float to adangerously high potential.

WARNING

Lethal voltage is used in the operational checkout of this unit. Death on contact mayresult if personnel fail to observe the following safety precautions. Remove watches andrings and exercise extreme caution when working inside the equipment throughout theremainder of this procedure.

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TM 11-5820-922-40-1

WARNING

Prior to performing the following functions all electrical power is to be removed from the system.External power disconnected and a “MAINTENANCE IN PROGRESS” tag attached or powerswitches will be locked out to prevent inadvertent energizing of the system.

WARNING

Lifting heavy equipment incorrectly can cause serious injury. Do not try to lift more than 35pounds by yourself. Get a helper. Bend legs while lifting. Don’t support heavy weight with yourback.

WARNING

Adequate ventilation should be provided while using TRICHLOROTRIFLUOROETHANE:Prolonged breathing of vapor should be avoided. The solvent should not be used near heat or openflame, the products of decompos i t ion a r e t o x i c a n d i r r i t a t i n g . SinceTRICHLOROTRIFLUOROETHANE dissolves natural oils, prolonged contact with skin shouldbe avoided. When necessary use gloves which the solvent cannot penetrate. If the solvent is takeninternally, consult a physician.

Compressed air shall not be used for cleaning purposes except where reduced to less than 29 psiand then only with effective chip guarding and personnel protective equipment. Do not usecompressed air to dry parts when TRICHLOROTRIFLUOROETHANE has been used.Compressed air is dangerous and can cause serious bodily harm if protective means or methods arenot observed to prevent chip or particle (of whatever size) from being blown into the eyes or un-broken skin of the operator or other personnel.

D

TM 11-5820-922-40-1

SAFETY SUMMARY

The warnings and cautions in this safety summary are as they appear in text.Included in these warnings and cautions is a paragraph reference as to where theyare located in the manual.

WARNING

Vapors emitted during certain circuit card repair procedures may be irri-tating to personnel. Always perform circuit card repair procedures in awell ventilated area. (3-17)

WARNING

Isopropyl alcohol is flammable. Keep away from heat and open flame.Vapors may be harmful. Use with adequate ventilation. Avoid prolonged orrepeated breathing of vapor. Avoid eye contact. Do not take internally.(3-22, 3-23, 3-39)

WARNING

Adhesives are irritating to the skin and eyes upon contact, and may emitharmful vapor. Use only with adequate ventilation. Avoid all skin and eyecontact. Use protective clothing such as rubber gloves, apron and eye pro-tection. Wash off immediately any accidentally contaminated skin area.Hand washing facilities and eye wash fountain should be provided. Do nottake internally. (3-22, 3-24, 3-35, 3-36, 3-37, 3-38)

WARNING

Handling hot items presents a serious injury potential. Asbestos glovesare required. (3-22, 3-24, 3-33, 3-34, 3-35, 3-36, 3-38)

WARNING

Polyurethane contains flammable solvents and toxic diisocyanates. Keepaway from heat and open flame. Vapors or mists are harmful! Complete bodyprotection, including entire head, is required to prevent skin or eye irri-tation from contact with the paint or its vapors or mists. Respirator pro-tection is required, usually an air-supplied hood, during mixing, curing,and application. Use this paint only with the protection requirements asspecified above. Suitable flushing facilities must be provided for immedi-ate clean water flushing or any accidental skin or eye contact. Do nottake internally. (3-22)

E

TM 11-5820-922-40-1

SAFETY SUMMARY (cont)

WARNING

Drilling operations create metal chips which may enter the eyes and causeserious injury. Eye protection in required. (3-23)

WARNING

Isopropyl alcohol is flammable. Keep away from heat and open flame.Vapors may be harmful. Use with adequate ventilation. Avoid prolonged orrepeated breathing of vapor. Avoid eye contact. Do not take internally.(3-23, 3-39)

WARNING

Toluene is flammable. Keep away from heat and open flame.ful. Use only with adequate ventilation. Avoid prolongedbreathing of vapor. Avoid contact with skin and eyes. Donally. Comply with air pollution control rules concerningreactive solvents. (3-24)

CAUTION

Vapors are harm-or repeatednot take inter-photochemically

Never apply excessive pressure against a circuit card. (3-25)

WARNING

Solvents used in this procedure are flammable and must be kept from openflame, heat, and sparks. Keep containers tightly closed and store them ina cool place when not being used. The solvent must be used only in anadequately ventilated environment. Avoid breathing vapors and repeated con-tact with skin. Clean hands thoroughly before smoking,eating, ordrinking. (3-33)

WARNING

Use Freon with good ventilation. Avoid prolonged or repeated breathing ofvapor. Avoid contact with skin and eyes. Do not take internally. (3-35,3-37, 3-38)

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TM 11-5820-922-40-1

SAFETY SUMMARY (cont)

CAUTION

The areas to be soldered must be heated until the solder flows. Over-heating can damage the board or nearby components. The wires beingsoldered must not be allowed to move in relation to one another until thesolder has completely solidified. (3-36, 3-37)

CAUTION

Do not cut down into the circuit card pad when trimming the wire. (3-39)

WARNING

When using a compressed air jet, use eye shields. (3-42)

WARNING

When using solvents, provide proper ventilation, avoid prolonged contact,and do not smoke. Solvents must meet all pertinent specifications regard–ing toxicity, flammability, and allergenic effect. (3-42)

CAUTION

Compressed air must be clean, dry, and at a maximum pressure of 28 psi. Donot overlook the force of the air jet when cleaning delicate parts. (3-42)

CAUTION

Certain solvents will damage insulation. Do not use solvents chemicallysimilar to “Chlorothene” or “Glyptal” to clean module connectors. Use onlydenatured alcohol for this purpose. (3-42)

CAUTION

Use extreme care when removing or replacing ribbon cables. Creasing orsevere bending will damage ribbon cables internally. (4-16, 4–17, 4-35)

G/(H blank)

Technical Manual

TM 11-5820-922-40-1

HEADQUARTERSDEPARTMENT OF THE ARMY

No. 11-5820-922-40-1 Washington, DC, 15 January 1986

GENERAL SUPPORT MAINTENANCE MANUAL

AMPLIFIER-CONVERTERAM-6879/URC

(NSN 5820-01-070-1950)

REPORTING ERRORS AND RECOMMENDING IMPROVEMENTS

You can help improve this manual. If you find any mistakes or if you know of a wayto improve the procedures, please let us know. Mail your letter, DA Form 2028(Recommended Changes to Publications and Blank Forms), or DA Form 2028-2located in the back of this manual direct to: Commander, US ArmyCommunications-Electronics Command and Fort Monmouth, ATTN: AMSEL-ME-MP, Fort Monmouth, NJ 07703-5007. A reply will be furnished to you.

Section

00-10-20-30-40-50-6

TABLE OF CONTENTS

PageWARNINGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A through G

GENERAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0-1Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0-1Consolidated Index of Army Publications and Blank Forms . . . . . . . . . . . . . . . . . . . . . 0-1Maintenance Forms, Records and Reports . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0-1Reporting Equipment Improvement Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . 0-1Adminstrative Storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0-1Destruction of Army Electronics Materiel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0-1

i

TM 11-5820-922-40-1

TABLE OF CONTENTS

Section

LIST OF ILLUSTRATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . .

LIST OF TABLES. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

I

CHAPTER 1. GENERAL INFORMATION

1-1 Scope of Technical Manual . . . . . . . . . . . . . . . . . .1-8 Reference Data.. . . . . . . . . . . . . . . . . . . . . . .

1-10 Technical Characteristics . . . . . . . . . . . . . . .1-11 Equipment Supplied . . . . . . . . . . . . . . . . . . .1-12 Support Equipment . . . . . . . . . . . . . . . . . . .1-14 Special Maintenance Facility Requirements . . . . . . .1-15 List of Publications . . . . . . . . . . . . . . . . . .

CHAPTER 2. THEORY OF OPERATION

OVERALL FUNCTIONAL DESCRIPTION . . . . . . . . . . . . . . . . . . .2-1 Amplifier-Converter Functional Description . . . . . . . . . .

2-3 EMI Filter. . . . . . . . . . . . . . . . . . . . . . .2-4 Audio Filter. . . . . . . . . . . . . . . . . . . . . .2-5 Amplifier-Squelch . . . . . . . . . . . . . . . . . . .

2-6 Receiver Operation . . . . . . . . . . . . . . . .2-7 Transmit Operation . . . . . . . . . . . . . . . .

2-8 TTY-FSK Converter . . . . . . . . . . . . . . . . . . .2-9 Receive Operation . . . . . . . . . . . . . . . .2-10 Transmit Operation . . . . . . . . . . . . . . . .

2-11 Radio Frequency Interference Filter . . . . . . . . . .

II DETAILED FUNCTIONAL DESCRIPTION . . . . . . . . . . . . . . . . . .

2-12 Amplifier-Converter Detailed Functional Description . . . . .2-14 EMI Filter. . . . . . . . . . . . . . . . . . . . . . .2-15 Audio Filter. . . . . . . . . . . . . . . . . . . . . .2-16 Amplifier-Squelch . . . . . . . . . . . . . . . . . . .

2-28 TTY-FSK Converter . . . . . . . . . . . . . . . .2-29 Receive Operation . . . . . . . . . . . . .2-30 Transmit Operation . . . . . . . . . . . . .2-32 DC Loop . . . . . . . . . . . . . . . . . .

2-23 RFI Filter. . . . . . . . . . . . . . . . . . . .

Page

vi

vii

1-11-11-11-11-11-61-6

2-12-12-12-12-12-12-12-12-12-22-2

2-5

2-52-52-52-5

2-112-122-122-152-15

i i

Section

TM 11-5820-922-40-1

TABLE OF CONTENTS (cont)

Page

CHAPTER 3. GENERAL MAINTENANCE DATA

3-1 General . . . . . . . . . . . . . . , . . . . . . . . . . . .

I CIRCUIT CARD ASSEMBLY REPAIR PROCEDURES . . . . . . . . . . . . . .

3-3 General . . . . . . . . . . . . . . . . . . . . . . . . . . .3-5 Standards . . . . . . . . . . . . . . . . . . . . . . . . . .

3-6 Soldering Standards for Circuit Cards . . . . . . . . .3-7 Soldering Voids . . . . . . . . . . . . . . . . .3-8 Soldering Pinholes . . . . . . . . . . . . . . . .3-9 Pad Area. . . . . . . . . . . . . . . . . . . . .3-10 Excessive Solder . . . . . . . . . . . . . . . . .3-11 Insufficient Solder . . . . . . . . . . . . . . .3-12 Cold Solder Joints . . . . . . . . . . . . . . . .3-13 Preferred Solder Connections . . . . . . . . . . .

3-14 Circuit Card Base Material Standards . . . . . . . . . .3-15 Circuit Card Etch Standard . . . . . . . . . . . . . . .3-16 Storage and Handling of Circuit Cards . . . . . . . . .

3-17 Circuit Card Repair Procedures . . . . . . . . . . . . . . . .3-19 Circuit Card Repair Tools and Materials . . . . . . . .3-20 Etch Repair . . . . . . . . . . . . . . . . . . . . . .

3-21 Repair of Scratched, Gouged, Voided orPinholed Etch . . . . . . . . . . . . . . . . .

3-22 Repair of Broken Gold-Plated Copper Etch . . . . .3-23 Repair of Raised or Unbonded Gold-Plated

Copper Etch . . . . . . . . . . . . . . . . .3-24 Replacement of a Lifted Pad . . . . . . . . . . . . . .3-25 Removal of Bonded Parts . . . . . . . . . . . . . . . .3-27 Removal of Soldered Components Having Axial Leads . . .3-28 Removal of Soldered Components Having Radial Leads . . .3-29 Removal of Transistors . . . . . . . . . . . . . . . . .3-30 Soldered Component Replacement . . . . . . . . . . . . .3-31 Component Replacement in Eyelets . . . . . . . . . . . .3-32 Component Replacement in Plated-Through Holes . . . . .3-33 Repair of Polyurethane Conformal Coating . . . . . . . .3-34 Repair of Damaged Fiber Glass Epoxy Parts . . . . . . .3-35 Modification of Solder-Plated Printed Wiring

Circuit Cards . . . . . . . . . . . . . . . . . . . .3-36 Repair of Broken Terminal Mounting Plate Power

or Ground Tabs. . . . . . . . . . . . . . . . . . . .3-37 Repair of Concealed Short Circuit in Printed

Wiring Assemblies . . . . . . . . . . . . . . . . . .3-38 Repair of Terminal Mounting Plate on High-Density

Printed Wiring Boards. . . . . . . . . . . . . . . .3-39 Repair of Defective Plated-Through Hole . . . . . . . .

3-1

3-2

3-23-23-23-23-23-23-23-23-23-23-23-53-53-53-63-8

3-83-8

3-103-103-113-123-123-123-123-123-133-133-14

3-14

3-19

3-21

3-223-23

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TM 11-5820-922-40-1


Section Page

II CLEANING AND EXAMINATION. . . . . . . . . . . . . . . . . . . . 3-24

3-40 General . . . . . . . . . . . . . . . . . . . . . . . . . . .3-42 Cleaning. . . . . . . . . . . . . . . . . . . . . . . . . . .

3-43 External. . . . . . . . . . . . . . . . . . . . . . . .3-45 Internal. . . . . . . . . . . . . . . . . . . . . . . .3-46 Corrosion Control . . . . . . . . . . . . . . . . . . .

3-47 Examination . . . . . . . . . . . . . . . . . . . . . . . . .3-48 General . . . . . . . . . . . . . . . . . . . . . . . .

3-49 Visual Inspection . . . . . . . . . . . . . . . .3-50 Troubleshooting Inspection . . . . . . . . . . . .3-51 Performance Test . . . . . . . . . . . . . . . . .

3-243-243-243-243-243-253-253-253-253-25

III FABRICATION OF TEST CABLES . . . . . . . . . . . . . . . . . . . . . 3-26

3-52 General . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-26

IV PERFORMANCE TEST AND TROUBLESHOOTING . . . . . . . . . . . . . 3-33

3-54 General . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-333-56 Performance Test and Troubleshooting . . . . . . . . . . . . . 3-33

3-58 Flowcharts. . . . . . . . . . . . . . . . . . . . . . . 3-333-59 Test and Troubleshooting Reference Data . . . . . . . . 3-333-60 Description of Component Location Diagrams . . . . . . . 3-36

CHAPTER 4. AMPLIFIER-CONVERTER AM-6879/URC

I INTRODUCTION. . . . . . . . . . . . . . . . . . . . . . . . .

4-1 Introduction. . . . . . . . .. . . . . . . . . . . . . . . .4-4 Test Equipment . . . . . . . . . . . . . . . . . . . . . . . .4-6 Special Tools and Materials . . . . . . . . . . . . . . . . .

II DISASSEMBLY AND REASSEMBLY . . . . . . . . . . . . . . . . . . . . .

4-8 Introduction. . . . . . . . . . . . . . . . . . . . . . . . .4-10 Disassembly . . . . . . . . . . . . . . . . . . . . . . . . .

4-12 Amplifier-Converter Rear Cover Assembly A1A3 Removal . .4-13 EMI Filter Assembly A1A3A1 Removal . . . . . . . . . . .4-14 Amplifier-Squelch Assembly A1A2 Removal . . . . . . . .4-15 TTY-FSK Converter Assembly A1A1 Removal . . . . . . . .4-16 Audio Filter Assembly A1A4A1 and Connector

Assembly Removal. . . . . . . . . . . . . . . . . . .4-17 Ribbon Cable Removal.. . . . . . . . . . . . . . . . .4-18 Speaker Assembly Removal . . . . . . . . . . . . . . . .4-19 TTY ON/OFF/SPKR ON S1 and Squelch Switch R1/S2 Removal .4-20 Meter Connectors TP1 and TP2 Removal . . . . . . . . . .4-21 Select Switch S3 Removal . . . . . . . . . . . . . . . .

4-1

4-14-14-1

4-4

4-44-44-44-44-44-4

4-44-54-54-54-54-5

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Section

4-22 Adjust Potentiometer R2 Removal . . . . . . . . . . .4-23 Amplifier-Converter Binding Post Removal . . . . . . . .4-24 Fuseholder XFl Removal . . . . . . . . . . . . .

4-25 Reassembly. . . . . . . . . . . . . . . . . . . . . . . . . .

III

IV

V

VI

4-274-284-294-304-314-324-334-344-354-36

4-374-384-394-40

Fuseholder XF1 Replacement . . . . . . . . . . . . . . .Binding Post Replacement . . . . . . . . . . . . . . . .Adjust Potentiometer R2 Replacement . . . . . . . . . .Select Switch S3 Replacement . . . . . . . . . . . . . .Meter Connectors TP1 and TP2 Replacement . . . . . . . .TTY ON/OFF/SPKR ON Switch S1 Replacement . . . . . . . .Squelch Switch R1/S2 Replacement . . . . . . . . . . . .Speaker Assembly Replacement . . . . . . . . . . . . . .Ribbon Cable Assembly Replacement . . . . . . . . . . .Audio Filter Assembly A1A4A1 and ConnectorAssembly Replacement.. . . . . . . . . . . . . . . .

TTY-FSK Converter Assembly A1A1 Replacement . . . . . .Amplifier-Squelch Assembly A1A2 Replacement . . . . . .EMI Filter Assembly A1A3A1 Replacement . . . . . . . . .Amplifier-Converter Rear Cover Assembly

A1A3 Replacement . . .

CLEANING AND EXAMINATION . . . . . .

4-41 Introduction . . . . . . . . .

PERFORMANCE TEST AND TROUBLESHOOTING

4-43 Introduction . . . . . . . . .

REPAIR AND REPLACEMENT . . . . . . .

4-45 Introduction . . . . . . . . .

COMPONENT LOCATION AND PARTS LIST .

. . . . . . . . . . .

.. . . . . . . . . . . . .

. . . . . . . . . . . ..

... . . . . . . . . ..

. . . . . . . . . . . . .

. . . . . . . ... . ...

. . . . . . . . . . . ... .

. . . . . . . . . .

4-47 Introduction. . . . . . . . . . . . . . . . . . . . . . . . .

APPENDIX A REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . .

Alphabetical Index. . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Page

4-64-64-64-64-64-64-74-74-74-74-74-84-8

4-84-84-84-8

4-9

4-10

4-10

4-11

4-11

4-12

4-12

4-13

4-13

A-1

Index- 1

v

TM 11-5820-922-40-1

LIST OF ILLUSTRATIONS

Figure

1-0

1-1

2-12-22-32-42-52-63-13-23-33-43-53-63-73-83-93-103-113-123-133-144-14-24-34-4

4-5

4-64-7

Title

Amplifier-Converter AM-6879/URC, Receiver/Exciter RT-1209/URC,and Electrical Equipment Mounting Tray MT-4874/URC . . . . . . . .

Typical Amplifier-Converter and Receiver/Exciter VehicleMounted Configuration . . . . . . . . . . . . . . . . . . . . . .

Functional Block Diagram . . . . . . . . . . . . . . . . . . . . . .EMI Filter A1A3A1 Detailed Block Diagram . . . . . . . . . . . . . .Audio Filter A1A4A1 Detailed Block Diagram . . . . . . . . . . . . .Amplifier-Squelch Detailed Block Diagram . . . . . . . . . . . . . .TTY-FSK Converter A1A1 Detailed Block Diagram . . . . . . . . . . .RFI Filter A1A4A2 Detailed Block Diagram . . . . . . . . . . . . . .Void Standards. . . . . . . . . . . . . . . . . . . . . . . . . . .Pinhole Standards . . . . . . . . . . . . . . . . . . . . . . . . .Solder Height Standards . . . . . . . . . . . . . . . . . . . . . .Cold Solder Joints. . . . . . . . . . . . . . . . . . . . . . . . .Preferred Solder Connections . . . . . . . . . . . . . . . . . . . .Coined 30-Gage Wire End . . . . . . . . . . . . . . . . . . . . . .Single-Wire Attachment to Printed Circuit Pad . . . . . . . . . . .Double-Wire Attachment to Printed Circuit Pad . . . . . . . . . . .Repair of Broken Terminal Mounting Plate Power or Ground Tabs . . .Fabrication of Test Cables and Adapters . . . . . . . . . . . . . .VM/RE Cable W1. . . . . . . . . . . . . . . . . . . . . . . . . . .Audio Cable W2. . . . . . . . . . . . . . . . . . . . . . . . . . .Flow Chart Symbology. . . . . . . . . . . . . . . . . . . . . . . .Maintenance Chapter Construction . . . . . . . . . . . . . . . . . .Amplifier-Converter A1 . . . . . . . . . . . . . . . . . . . . . . .Amplifier-Converter A1 Schematic . . . . . . . . . . . . . . . . . .Amplifier-Converter A1 Power Distribution . . . . . . . . . . . . .Amplifier-Converter Component Location (Rear Cover Assembly A1A3,

Circuit Cards, Switches and Fuse) (3 Sheets) . . . . . . . . . . .Amplifier-Converter Component Location (Ribbon Cable and Connectors)

(2 Sheets). . . . . . . . . . . . . . . . . . . . . . . . . . . .Amplifier-Converter A1 Test Setup . . . . . . . . . . . . . . . . .Amplifier-Converter A1 Performance Test . . . . . . . . . . . . . .

Page

1-0

1-22-32-62-72-9

2-132-163-33-33-33-43-4

3-163-173-183-203-273-293-313-343-354-2

4-154-17

4-19

4-254-294-31

v i

TM 11-5820-922-40-1

Table

1-11-21-31-41-53-13-24-14-2

LIST OF TABLES

Title

Technical Characteristics . . . . . . . . . . . . . . . . . . . . .Equipment Supplied . . . . . . . . . . . . . . . . . . . . . . . . .Test Equipment. . . . . . . . . . . . . . . . . . . . . . . . . . .Special Tools, Materials, and Fabricated Cables . . . . . . . . . .List of Publications . . . . . . . . . . . . . . . . . . . . . . . .Recommended Tools . . . . . . . . . . . . . . . . . . . . . . . . .Recommended Materials . . . . . . . . . . . . . . . . . . . . . . .Test Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . .Special Tools, Materials, and Fabricated Test Cables . . . . . . . .

Page

1-31-41-51-51-63-63-64-14-3

vii/(viii blank)

TM 11-5820–922-40-1

SECTION 0

GENERAL

0-1. SCOPE. This manual covers general support maintenance for Amplifier-Converter AM-6879/URC. Thismanual provides instructions for general support maintenance repair personnel.

0-2. CONSOLIDATED INDEX OF ARMY PUBLICATIONS AND BLANK FORMS. Refer to the latest issue ofDA Pam 310-1 to determine whether there are new editions, changes or additional publications pertaining to theequipment.

0-3. MAINTENANCE FORMS, RECORDS, AND REPORTS

a. Reports of Maintenance and Unsatisfactory Equipment. Department of the Army forms and procedures usedfor equipment maintenance will be those prescribed by DA Pam 738-750 as contained in Maintenance ManagementUpdate.

b. Report of Packaging and Handling Deficiencies. Fill out and forward SF 364 (Report of Discrepancy (ROD))as prescribed in AR 735-11-2/DLAR 4140.55/NAVMATINST 4355.74A/AFR-400-54/MCO 4430.3F.

c. Discrepancy in Shipment Report (DISREP) (SF 361). Fill out and forward Discrepancy in Shipment Report(DISREP) (SF 361) as prescribed in AR 55-38/NAVSUPINST 4610.33 C/AFR 75-18/MCO P4610. 19/DLAR 4500.15.

0-4. REPORTING EQUIPMENT IMPROVEMENT RECOMMENDATIONS (EIR). If Amplifier-ConverterAM-6879/URC needs improvement, let us know. Send us an EIR. You, the user, are the only one who can tell us whyyou don’t like the design. Put it on an SF 368 (Quality Deficiency Report). Mail it to Commander, US ArmyCommunications-Electronics Command and Fort Monmouth, ATTN: AMSEL-ME-MP, Fort Monmouth, NewJersey 07703-5007. We’ll send you a reply.

0-5. ADMINISTRATIVE STORAGE. Administrative Storage of equipment issued to and used by Army activitieswill have preventive maintenance performed in accordance with the PMCS charts before storing. When removing theequipment from administrative storage the PMCS should be performed to assure operational readiness. Disassemblyand repacking of equipment for shipment or limited storage are covered in TM 740-90-1.

0-6. DESTRUCTION OF ARMY ELECTRONICS MATERIEL. Destruction of Army electronics materiel to pre-vent enemy use shall be in accordance with TM 750-244-2.

0-1

Figure 1-0.

TM 11-5820-922-40-1

1-0

TM 11-5820-922-40-1

CHAPTER 1

GENERAL INFORMATION

1-1. SCOPE OF TECHNICAL MANUAL.

1-2. This technical manual providesfield maintenance information cover-ing Amplifier-Converter AM-6879/URC(amplifier-converter) at the unit level.Field maintenance information for thecircuit card assemblies is contained inGeneral Support Maintenance ManualTM 11-5820-922-40-2. For depot rebuild standards,refer to RebuiId Standards ManualRS-07749A/07743A-50/5. For parts ordering data,refer to Repair Parts and Special Tools ListTM 11-5820-924-24P.

1-3. The amplifier-converter (fig 1-1)is mounted on Electrical Equipment Mount-ing Tray MT-4874/URC (mounting tray),together with Receiver-TransmitterRT-1209/URC (receiver/exciter), for useas part of Radio Set AN/GRC-193 (refer toTM 11-5820-924-12. For coverage of thereceiver/exciter (which also part of RadioSet AN/PRC-104A) refer to Operator’s andOrganizational Maintenance ManualTM 11-5820-919-12, General Support MaintenanceManual TM ll-5820-919-40-1, General SupportMaintenance Manual TM 11-5820-919-40-2, andRebuild Standards RS-07748A-50/4. For parts order-ing data, refer to Repair Parts and Special Tools ListTM 11-5820-919-24P .

1-4. Chapter 1 of this technical manualprovides information on the physicalaspects and performance characteristicsof the amplifier-converter and containsgeneral reference data.

1-5. Chapter 2 contains general anddetailed theory of operation of theamplifier-converter.

1-6. Chapter 3 provides general mainte-nance data that is applicable to all theassemblies. It includes circuit cardassembly repair procedures, cleaning andexamination, fabrication of test cablesand adapters, and instructions on use ofthe performance test and troubleshooting

flowcharts. Cable diagrams for the twocables connecting to the receiver/exciter are also included.

1-7. Chapter 4 provides the maintenanceinformation necessary to test, trouble-shoot, and repair the amplifier-converterunit down to circuit card assembly level.It is sectionalized in the followingsequence: (1) disassembly and reassem-bly, (2) cleaning and examination, (3)performance test and troubleshooting,(4) repair and replacement, (5) compo-nent location and parts list, and (6)maintenance diagrams.

1-8. REFERENCE DATA.

1-9. The following paragraphs providereference data for planning the mainte-nance of the amplifier-converter.

1-10. TECHNICAL CHARACTERISTICS. Tech-nical characteristics for the amplifier-converter are listed in table 1-1.

1-11. EQUIPMENT SUPPLIED. Theamplifier-converter and related equip-ment are listed in table 1-2.

1-12. SUPPORT EQUIPMENT. The testequipment required for complete fieldmaintenance of the amplifier-converteris listed in table 1-3. Equivalent testequipment may be used.

NOTE

Use only test equipment thatis properly calibrated. Fail-ure to do so may provide erro-neous and misleading performanceor fault indications.

1-13. The special tools, materials, andfabricated test cables and fixturesrequired for field maintenance of theamplifier-converter are listed in table1-4.

1-1

TM 11-5820-922-40-1

1-2

Figure 1-1. Typical Amplifier-Converter and Receiver/ExciterVehicle-Mounted Configuration

TM 11-5820-922-40-1

TABLE 1–1. TECHNICAL CHARACTERISTICS

Characteristic Description

Overall power gain

TTY-FSK modulationaccuracy

Data transmission rate

Squelch response(attack time)

Squelch sensitivity

Audio distortion

Audio output

Input voltage

27 db with 2-mw input from receiver/exciter

±0.005 percent

75 baud (standard teletypewriter)

Approximately 30 ms

10 to 20 db signal-to-noise ratio

5 to 7 percent

Approximately 1 watt to loudspeaker in receive mode(loudspeaker is muted during transmit operation)

20 to 30 vdc

1-3

TA

BLE

1-2.

TM 11-5820-922-40-1

1-4

TM 11-5820-922-40-1

TABLE 1-3. TEST EQUIPMENT

Name

Audio Oscillator

Oscilloscope

Digital Multimeter

Frequency Counter

Power Supply, DC

Multimeter

Designation

AN/URM-127

AN/USM-338

AN/USM-341

CP-843P/U

Hewlett-PackardHP-6439B

Simpson 260-6P

Item Parameters

±2 percent accuracy, 0.5 to 6 kHz

Bandwidth extending to 50 kHz withexternal triggering available,10-mv sensitivity

High impedance (ohmmeter), ac anddc, 0 - 30v, ±0.l percent

50 Hz - 5 MHz, readings in 1-Hzincrements at 5 MHz

0 - 30v, 7 amp max

Ammeter function, ±1 percent

TABLE 1-4. SPECIAL TOOLS, MATERIALS, AND FABRICATED CABLES

NOTE: Referenced figures are contained in Chapter 3.

Description

Kit, Tool, Electronic

Bench Repair Center

Maintenance Kit, Printed Circuit

Conformal Coating

Power Cable

Card Extender Cable

Audio Connector Adapter

Power On/Off Switch Connector

TTY Jumper

TTY Load Resistor

Maint Kit Group Elec Equip

Part Number

TK-100/G

Pace PRC-350C

MK-984/A

MIL-I-46048, Type UR

...

...

...

...

...

...

OA-9163/GRC-193A

Quantity

1

1

1

1

1

1

Reference

. . .

...

...

...

Figure 3-10A

Figure 3-10B

Figure 3-10C

Figure 3-10D

...

...

1-5

TM 11-5820-922-40-1

1-14. SPECIAL MAINTENANCE FACILITYREQUIREMENTS. There are no specialma in tenance fac i l i ty r equ i rements fo rt h e a m p l i f i e r - c o n v e r t e r .

to the ampl i f i e r -conver t e r and ther e c e i v e r / e x c i t e r .

1-15. LIST OF PUBLICATIONS. Table 1-5l i s t s t h e c u r r e n t p u b l i c a t i o n s a p p l i c a b l e

TABLE 1-5. LIST OF PUBLICATIONS

T i t l e Publication Number

Amplifier-Converter AM-6879/URC

Operator’s and OrganizationalMaintenance Manual Radio Sets AN/GRC93Aand the AN/MRC-138A

Operator’s and OrganizationalMaintenance Manual

General Support Maintenance Manual

General Support Maintenance Manual

Rebuild Standards

Repair Parts and Special Tools List

TM 11-5820-924-12

TM 11-5820-922-12

TM 11-5820-922-40-1

TM 11-5820-922-40-2

RS-07749A/07743A-50/5

TM 11-5820-924-24P

Receiver-Transmitter RT-1209/URC(Part of Radio Set AN/PRC-104(A)

Operator’s and Organizational TM 11-5820-919-12Maintenance Manual

General Support Maintenance TM 11-5820-919-40-1Manual

General Support Maintenance TM 11-5820-919-40-2Manual

Rebuild Standards RS-07748A-50/4

Repair Parts and Special Tools List TM 11-5820-919-24P

1-6

TM 11-5820-922-40-1

CHAPTER 2

THEORY OF OPERATION

SECTION I

OVERALL FUNCTIONAL DESCRIPTION

2-1. AMPLIFIER-CONVERTER FUNCTIONALDESCRIPTION (Figure 2-1).

2-2. The amplifier-converter, when usedin conjunction with an rf amplifier, areceiver/exciter, a coupler, and anantenna, constitutes a single-sideband

(SSB) transceiver. Refer to TM 11-5820-919-40-1 forinformation on Receiver/Exciter RT-1209/URC; forthe other components refer to TM 11-5820-924-12.The amplifier-converter provides amplification ofreceived audio signals to drive the loudspeakermounted on the front panel. Teletypewriter (TTY)signal conversion is also performed in TTY receiveand transmit. Functionally, the amplifier-convertercontains the following:

2-3. EMI FILTER. The EMI filter isused as a protection filter for theamplifier-converter. It blocks high-power rf radiation, and is necessarybecause of the close proximity ofthe radiating antenna to theamplifier-converter.

2-4. AUDIO FILTER. The audio filter isa protection device for the amplifier-converter. It passes signals below 3000Hz, and blocks rf energy which emanatesfrom the system antenna.

2-5. AMPLIFIER-SQUELCH. The amplifier–squelch circuitry automatically quietsthe Rcv Audio by reducing its responseto incoming signals (Rev Audio) below apreselected level. During transmitoperation, the amplifier-squelch mutesthe loudspeaker.

2-6. Receive Operation. In voice com-munication, the Rcv Audio In from thereceiver/exciter assembly is applied toa clipper/limiter circuit and the squelch

gate. A detector circuit produces anenvelope of the Rcv Audio In and appliesthe signal to a filter which removes allfrequencies above 25 Hz (normal voiceenvelope range). The voice envelope isthen applied to a comparator for compar-ison with the audio envelope. If thevoice envelope is present (voice signalsare being received), the comparator pro-duces a Squelch Control signal to turnon the squelch gate. If the voice enve-lope is not present (no voice signalsbeing received), or if noise is toohigh, the squelch gate is turned off.This prevents the Rcv Audio In signalfrom being presented to the operatorwhen noise is high or when there is novoice (or cw) input.

2-7. Transmit Operation. In transmitoperation, the PTT signal from thereceiver/exciter gates off the squelchgate circuit. This action mutes theloudspeaker, while transmitting, to pre-vent audio feedback from the loudspeakerto the microphone.

2-8. TTY-FSK CONVERTER. The TTY-FSKconverter converts dc signals from alocal teletypewriter to audio signals(Xmt Audio) for the receiver/exciter.The TTY-FSK converter also convertsreceived TTY signals (Rcv Audio In)to dc signals to drive the localteletypewriter.

2-9. Receive Operation. In receiveteletype operation, the Rcv Audio Infrom the receiver/exciter is applied toa Mark filter and a Space filter. Thetwo filters separate the Mark frequency(1575 Hz) and the Space frequency (2425Hz) within the Rcv Audio In. The out–puts from the filters are detected toproduce the Rcv TTY signal (a binary

2-1

TM 11-5820-922-40-1

signal). The Rcv TTY signal is used tocontrol the dc loop circuitry. The out-put of the dc loop is either 20, 60, or0 milliamperes and is used to drive theteletypewriter.

2-10. Transmit Operation. In teletypetransmit operation, coded TTY pulsesfrom the teletypewriter are used in thedc loop to produce Mark/Space currentpulses. The Mark/Space pulses control afrequency divider circuit driven by acrystal oscillator. The combination gen-erates the audio frequency shift keying

(AFSK) tones, consisting of 1575 Hz fora Mark and 2425 Hz for a Space. TheAFSK audio tones are then applied to thereceiver/exciter assembly to generatethe Xmt RF output in teletype operation.

2-11. RADIO FREQUENCY INTERFERENCEFILTER. The radio frequency interfer-ence (rfi) filter is used to protect theTTY-FSK converter from voltage spikesand rfi which may be picked up on thelocal teletypewriter transmit andreceive lines.

2-2

T M 1 1 - 5 8 2 0 - 9 2 2 - 4 0 - 1

Figure 2-1. Functional Block Diagram

2-3/(2-4 blank)

TM 11-5820-922-40-1

SECTION II

DETAILED FUNCTIONAL DESCRIPTION

2-12. AMPLIFIER-CONVERTER DETAILEDFUNCTIONAL DESCRIPTION.

2-13. The following paragraphs detailthe functions of the amplifier-converter.

2-14. EMI FILTER (Figure 2-2). The EMIfilter is used primarily as a low-passL-C filter network to pass low frequencysignals routed between the receiver/exciter and the power amplifier. Itblocks rf signals that may be presentduring transmit operation. Also, theEMI filter receives +28v Battery fromthe power amplifier, and routes +28vBattery (Protected) out to the receiver/exciter. A Tune In Progress signal isrouted from the power amplifier throughthe L-C filter network and then to thereceiver/exciter and the TTY-FSKconverter.

2-15. AUDIO FILTER (Figure 2-3). Theaudio filter is a low-pass L-C filternetwork used to filter some of the sig-nals routed between the operator’s hand-set, receiver/exciter, and the TTY-FSKconverter and the amplifier-squelch.Connector J1 will normally have thehandset connected to it, but will alsoaccept the continuous wave (CW) key.The following signals are routed throughthe low-pass L-C filter network: KY65Keyline, Rcv Audio In, Sidetone RcvAudio, AFSK, and PTT.

2-16. AMPLIFIER-SQUELCH (Figure 2-4).The amplifier-squelch employs circuitswhich are sensitive to the signal charac-teristics of the human voice. The pres-ence of a voice signal in the Rcv AudioIn will activate circuits which comparethe voice signal with a preset signal-to-noise ratio. The result of this compari-son is then used to squelch the receivedaudio signal. The level, or amount ofvoice signal, required to squelch theaudio signal is variable, and is con-trolled by the SQUELCH SENSITIVITYcontrol.

2-17. With SQUELCH turned on, Rcv AudioIn from the receiver/exciter is appliedto voice-operated gain device (VOGAD)amplifier U2. The VOGAD amplifier cir-cuit maintains a gain-controlled audiooutput of approximately 100 millivoltsregardless of the audio input. Clippercircuit CR3 and CR4 removes any high-level transients from the VOGAD audiooutput . Amplifier AR1 then boosts theVOGAD audio to a practical operatinglevel of approximately 4.5v, peak-to-peak.

2-18. The output of AR1 is applied tosignal detector CR5 and also to enve-lope detector CR2 and CR6. The positive-going portion of the VOGAD audio ispassed by signal detector CR5 andapplied directly to the inverting inputof subtracter AR4. The output of CR5represents the signal-plus-noise energyat the output of AR1. The signal-plus-noise energy is routed through signalcompensator Q3 if the signal drops by2 db. Therefore, if a signal is weakand just barely breaks squelch, it candegrade by 2 db and still keep squelchbroken.

2-19. Envelope detector CR2 and CR6rectifies the VOGAD audio and producesa negative-going audio envelope which ispassed through low-pass filter AR2. Theoutput of AR2 is a signal which followsthe audio envelope and, therefore, var-ies according to the syllabic rate ofthe voice energy in the audio signal.The cutoff frequency of AR2 is 25 Hz;therefore, noise and continuous tonesignals are rejected.

2-20. The syllabic rate signal from low-pass filter AR2 is routed through SQUELCHSENSITIVITY control R1 to variable gainamplifier AR3. The gain of AR3 is vari-able from 3 to 33 as determined by thesetting of R1. The output from AR3 isdetected by peak detector CR7 and C22and applied to the noninverting input ofsubtracter AR4.

2-5

FIG 2-4

FIG 2-4 FIG 2-5

FIG 2-4

FIG 2-5

TM 11-5820-922-40-1

Figure 2-2. EMI Filter A1A3A1 Detailed Block Diagram

2-6

Figure 2-3.

FIG. 2-4 FIG 2-4

FIG. 2-4

FIG. 2-5

FIG 2-5

FIG 2-4

TM 11-5820-922-40-1

2-7/(2-8 blank)

TM 11-5820 -922 -40 -1

Figure 2-4. Amplifier-Squelch A1A2Detailed Block Diagram

2-9/(2-10 blank)

TM 11-5820-922-40-1

2-21 At subtracter AR4, if the non-inverting input (syllabic rate) isgreater than the inverting input (signal-plus-noise level), the voice gate con-trol output will be positive. The mag-nitude of the positive voice gate signalis proportional to the voltage differ-ence between the inputs to subtracterAR4 If the inverting input (signal-plus-noise) to AR4 is greater than thenoninverting input, the voice gate out-put will drop to zero.

2-22. The voice gate output from AR4 isapplied to voice gate control AR5 whichdevelops a Squelch Control signal. TheSquelch Control signal is used to con-trol audio gate U3 as follows:

1. If the syllabic rate input to AR4is larger than the signal-plus-noise input, the voice gate willturn on AR5 which outputs a highSquelch Control signal and gateson U3. Rcv Audio In is thenrouted through U3 and is outputas squelched audio.

2. If the signal-plus-noise is largerthan the syllabic rate, the voicegate is low, the squelch controlis low, and the audio gate is cutoff. In this condition, Rcv AudioIn is not passed through audiogate U3.

2-23. SQUELCH ON/OFF switch S2 preventsthe Squelch Control signal from going toaudio gate U3 when squelch operation isnot selected. When this conditionexists, Rcv Audio In is routed around U3to the handset or loudspeaker.

2-24. The PTT signal from the handsetcuts off audio gate U3 and variable gainamplifier AR3 during transmit operation.A small portion of the Xmt Audio signalis routed back through audio gate U3 andbuffer Q4, and out to the handsetreceiver as Sidetone/Rcv Audio.

2-25. During normal receive operation,the squelched audio is routed to opera-tional amplifier AR6. The output of AR6(approximately 10 milliamperes) is notlarge enough to drive the loudspeaker,so the 10-milliampere audio signal isrouted to the complementary symmetrypush-pull amplifier. This amplifier,consisting of Q5 and Q7, and Q6 and Q8,boosts the Rcv Audio to approximately1 watt. At this point the audio signalis called Amplified Rcv Audio, beforebeing applied to the loudspeaker. Whenno signal is being received and thesquelch is on, a -30-db noise signal isrouted to the loudspeaker which producesa slight hiss to assure the operatorthat the equipment is still operating.

2-26. The dc power from the vehicle sys-tem is routed through the rf amplifierto the series dc limiter circuit (Q1,Q2). The series dc limiter protects thereceiver/exciter from overvoltage andtransient voltages. If the dc powergoes above +33v, the series dc limiterwill limit the voltage applied to thereceiver/exciter. If the voltageremains at +33v, the series dc limiterwill remain saturated (inoperative),and the output voltage level will be thesame as the input. Protection frompolarity reversal is provided by CR1before +28v Battery is applied to theseries regulator (Q1, Q2, and VR1).

2-27. The +28v On from the receiver/exciter is routed to power supply U1.The outputs of U1 are +12v and +6.4v andare used in this card. The +12v signalis also routed to the TTY-FSK converter.

2-28. TTY-FSK CONVERTER (Figure 2-5).The TTY-FSK converter serves as an inter-face unit between the teletypewriter andthe receiver/exciter. The TTY-FSK con-verter demodulates the Rcv Audio beforeit is routed to the teletypewriter andmodulates the transmit teletypewritersignals before they are routed to thereceiver/exciter.

2-11

TM 11-5820-922-40-1

2-29. Receive Operation. In thereceive mode of operation, Rcv Audio isrouted from the receiver/exciter intothe TTY-FSK converter via P1-9. RcvAudio is amplified in amplifier AR1, androuted through clipper CR1 and CR2 toclip and square the amplified signal.The output of the clipper is approxi-mately 1.4v p-p, with Marks representedby approximately 1575 Hz, and Spacesrepresented by approximately 2425 Hz.The Spaces are routed to narrow bandpassfilter (2425 Hz) AR1, and the Marks arerouted to narrow bandpass filter (1575Hz) AR1. The Marks and Spaces arerouted to CR3-C5 and CR5-C9 detectorcircuits, respectively. The dc leveloutputs of the detector circuits areapplied to comparator AR1, where the dclevels either gate-on or gate-off thecomparator to produce a binary output.The binary output is applied to the baseof Q2. If the base of Q2 is positive,it will turn on and close the dc loop.(The dc loop performs the electricalinterface between the TTY-FSK converterand the teletypewriter, and is used inboth receive and transmit modes of oper-ation.) When the dc loop is closed, itproduces a Mark in the teletypewriter.When the dc loop is open (negative pulseat the base of Q2, shutting Q2 off), aSpace is produced. The dc loop can beswitched from 60 milliamperes operationto 20 milliamperes operation dependingon the type of teletypewriter used.

2-30. Transmit Operation. In thetransmit mode of operation, the TTY KEYswitch on the teletypewriter is placedin the transmit position, which putsP1-25 at ground potential forward-biasing CR4. When CR4 is forward-biased, a ground potential is appliedto P1-17, the receiver/exciter PTT line,which places the receiver/exciter in thetransmit mode. Placing the TTY KEY switchin the transmit position also applies alow potential to the noninverting inputof AR1 (2425-Hz narrow bandpass filter).The low potential output of this filteris applied to the inverting input of theAR1 comparator, the output of which is ahigh potential. The high potential out-put of the AR1 comparator is applied to

the base of Q2 and turns it on, whichcloses the dc loop, making it possiblefor the teletypewriter to apply itsbinary-coded output to the FSK tone gen-erator. The heart of the FSK tone gener-ator is the crystal oscillator (consist-ing primarily of Y1, U1-12 and -13, R29,C14, and C15). When P1-25 is at groundpotential, the crystal oscillator willoperate at 4.88880 MHz. If the operat-ing frequency is changed on the receiver/exciter control panel, a Tune In Prog-ress signal is applied to P1-22, whichcuts off the crystal oscillator untiltuning is completed. The output of thecrystal oscillator is a sine wave and isrouted to the buffer U1. The sine wavegates the buffer on and off to produce asquare-wave output. The square-wave out-put is applied to the programmabledivider circuit U2 and U3.

2-31. The dc loop is opened and closeddepending on whether a Mark or a Spacehas been received from the teletype-writer. At U1 inverting amplifier, alow potential indicates a closed dcloop, or a Mark, and a high potentialindicates an open dc loop, or a Space.A Space is routed in on U1 inverting am-plifier and out as a low potential.This low potential, representative of aSpace, and the high potential at U1input are applied to programmabledivider U2 and U3 and turn on the divide-by-63 network. The frequency out of thedivide-by-63 network (77.6 kHz) isrouted through the symmetrical divide-by-32 flip-flop U4, and the resulting2425-Hz output is applied to the outputbuffer circuit and output to thereceiver/exciter as an AFSK signal. AMark is routed in on U1 invertingamplifier and out as a high potential.This high potential, representative of aMark, and the low potential at U1 input

are applied to programmable divider U2and U3 and turn on the divide-by-97network. The frequency out of thedivide-by-97 network (50.4 kHz) isrouted through the symmetrical divide-by-32 flip-flop, and the resulting1575-Hz output is applied to the outputbuffer circuit and outputted to thereceiver/exciter as an AFSK signal.

2-12

T M 1 1 - 5 8 2 0 - 9 2 2 - 4 0 - 1

Figure 2-5. TTY-FSK Converter A1A1Detailed Block Diagram.

2-13 / (2 -14 b lank)

TM 11-5820-922-40-1

2-32. DC Loop. The dc loop performs asan interface, as previously stated, butis also a constant current source forthe teletypewriter. This current sourceis switchable on the amplifier-converterfront panel for either 60 or 20 milli-amperes, depending on the type of tele-typewriter unit used. Also mounted onthe front panel is a dc loop currentadjust potentiometer. This potentiom-eter is used to adjust the dc loop cur-rent to exactly 20 or 60 milliamperes,if necessary. VR1 is a 4.3v Zener diodewhich is temperature-compensated by CR6.VR1 and CR6 in parallel with the dc loopcurrent adjust potentiometer, and R19and R20, comprise the major componentsof the dc loop.

2-33. RFI FILTER (Figure 2-6). Theradio frequency interference (rfi)filter is located between the DC LOOPand TTY KEY terminals and the TTY-FSKconverter. The rfi filter blocks rfithat could damage internal componentsor cause erroneous outputs.

2-34. Relay type teletypewriter unitshaving an external loop voltage sourcecan produce relay voltage spikes. Thesespikes are suppressed by CR1 in the rfifilter. The Zener diode (VR1) is usedto shunt to ground any incoming voltagesif the amplifier-converter dc loopdevelops a major malfunction.

2-15

Figure 2-6.

FIG 2-5

TM 11-5820-922-40-1

2-16

TM 11-5820-922-40-1

CHAPTER 3

GENERAL MAINTENANCE DATA

3-1 . GENERAL. amplifier-converter and circuitcards.

3-2. This chapter provides maintenanceinformation of a general nature that isapplicable to the maintenance and repair Section III. Fabrication of Test Cablesof the amplifier-converter in chapter 4 and the circuit card assemblies coveredin General Support Maintenance ManualTM 11-5820-922-40-2. Chapter 4 and the GeneralSupport Maintenance Manual identify and referencethe particular maintenance information of this chapterthat is applicable. The maintenance information ispresented as follows:

Section I. Circuit Card Assembly RepairProcedures.

and Adapters.

Contains information for fabrica-tion of special cables and adaptersrequired to perform the performancetests for the amplifier-converterand circuit cards. Cable diagramsfor the VM/RE and audio cables arealso included.

Section IV. Performance Test and

Contains description and definition Troubleshooting.

of standards to be observed, fol-lowed by procedures to be performed, Contains description and use of the

for repair of circuit cards and performance test and troubleshooting

replacement of components.

Section II. Cleaning and Examination.

Contains general information forthe cleaning and inspection of the

flowcharts in conjunction with othersupporting data for maintenance chap-ters 4, 5, and 6. (Static tests areused in maintenance chapters 7, 8,and 9 and are not described becauseof their simplicity.)

NOTE

Maint Kit OA-9163/GRC-193A is used as aMaintenance Test Bed.

3-1

TM 11-5820-922-40-1

SECTION I

CIRCUIT CARD ASSEMBLY REPAIR PROCEDURES

3-3. GENERAL.

3-4. This section contains descriptionand definitions of standards to beobserved followed by procedures to beperformed for repair of circuit cardsand replacement of components. Read theprocedures in this section beforeattempting card repair.

3-5. STANDARDS.

3-6. SOLDERING STANDARDS FOR CIRCUITCARDS. The following paragraphs containstandards to be observed when solderingcircuit cards.

permisssible voids and pinholes, the

3-7. Soldering Voids. A void (fig 3-1)is an area which is not filled withsolder, the extent of which is com-pletely visible. For cards with eyeletsor plated-through holes, voids in thecircuit side of a solder joint are per-missible, provided that they are notdeeper than half of the hole depth anddo not extend over more than a quarterof the hole area. If no circuit is con-nected to the pad on the side of thevoid, the void may extend over theentire hole area if the outline of thelead is visible. Voids in unsupportedholes may extend through the hole butshould not extend over more than a fifthof the hole area.

3-8. Soldering Pinholes. A pinhole isa hole in the surface of the solderwhich indicates the absence of solderbeneath the surface, the extent of whichis not visible. Pinholes (fig 3-2)should not be permitted adjacent to thecomponent lead or wire.

3-9. Pad Area. Solder is not requiredto cover the entire pad area. Voids andpinholes in these areas are acceptable.

3-10. Excessive Solder. Solder thatflows beyond the bend radius of a com-ponent lead is not acceptable, exceptfor small diameter components (forexample, glass diodes). The maximumsolder height, including component lead,on the bottom of the board is 0.062 inchfig 3-3). Solder spikes should notexceed 0.062 inch.

3-11. Insufficient Solder. Except for

solder must fill the hole to the pointwhere the solder covers the entire innersurface of the hole. For eyelet holesor standoff terminals with circuit con-nections, the solder should flow betweenthe eyelet and the pad for at least four-ifths of the circumference.

3-12. Cold Solder Joints. Cold solderjoints (fig 3-4) where the solder ballsat the point of contact with a pad orlead are not acceptable.

3-13. Preferred Solder Connections.All components may be soldered by eitherflow soldering or by hand soldering.The completed joint must have a clear,smooth appearance which indicates propersoldering. Examples of preferred solderconnections are shown in figure 3-5.

3-14. CIRCUIT CARD BASE MATERIALSTANDARDS. Cracks, chips, or gouges inthe base material should not exceed thefollowing:

1. Cracks or chips should not exceedback from the edge of the hole more than0.040 inch.

2. Cracks, chips, and gouges at theedge of the board should not exceed 1/3of the board thickness or extend backmore than 0.12 inch from the edge.

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Figure 3-1. Void Standards

Figure 3-2. Pinhold Standards

Figure 3-3. Solder Height Standards

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Figure 3-4. Cold Solder Joints

Figure 3-5. Preferred Solder Connections

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TM 11-5820-922-40-1

3. Cracks,acceptable onthe board.

chips, and gouges are notthe contact strip edge of

4. Cracks or chipsfrom one conductor to

5. Delamination ofis not acceptable.

should not extendanother conductor.

the base material

3-15. CIRCUIT CARD ETCH STANDARDS.Circuit card etch standards are asfollows:

1. Cracks, pits, or voids in thecontact strip area are not acceptable.

2. Scratches which expose the copperare not acceptable.

3. Cracks, pits , or voids in any etchwhich reduce the conductor by more than20 percent are not acceptable. Nodefect should reduce the conductor toless than 0.010 inch.

4. Lifting of a conductor above thesurface of the board is not acceptable.

5. Reduction in the area of any padin excess of 25 percent is not accept-able.extend

3-16.CARDS.should

Cracks, pits, or voids should notto a plated-through hole.

STORAGE AND HANDLING OF CIRCUITWhen stored, circuit cardsbe wrapped individually in poly-

ethylene bags , or equivalent, andstacked in storage pans. Other objectsshould not be placed in the storage panswith circuit cards. Avoid touching thecircuit card surface with bare hands orfingers. Handle the circuit card by itsedges.

3-17. CIRCUIT CARD REPAIR PROCEDURES.

WARNING

Vapors emitted during certaincircuit card repair proceduresmay be irritating to personnel.Always perform circuit cardrepair proceduresventilated area.

in a well

3-18. The repair of circuit cardsrequires proper tools and careful workhabits. Excessive heat when soldering,or undue force applied to components orto the circuit card, can seriously dam-age the assembly. In general, the fol-lowing precautions should be observed:

1. Never try to save a component partat the possible expense of damaging acircuit card. Most component parts canbe clipped from the circuit card. Whenclipping, the defective part, be carefulto protect the printed circuit conductor(etch) and other component parts.

2. A vacuum resoldering unit shouldbe used, if available, to remove theleads of a clipped part. The technicalmanual for the vacuum resoldering unitcontains operating procedures for theunit. Basically, the vacuum resolderingunit operates as follows: a high flowhole, across the pads and around theleads to remove the solder and cool downthese areas to prevent reseating of thelead. At the same time, the temperature-controlled desoldering tip, which ini-tially provided the heat to melt thesolder, is cooled rapidly by the airflow to prevent further heat from beingapplied to the workpiece. Once the airflow is stopped, the tip heats up rap-idly for continued vacuum desoldering.The coaxial, in-line design of the hand-piece allows molten solder and clippedleads to be drawn into the heat-resistantchamber where solder is solidified.

3. Exercise care when using a sol-dering iron to remove the leads of aclipped part, to connect a new part, orto service the circuit card itself.Circuit cards are easily damaged byheat. Prolonged application of heatwill destroy the adhesive quality of thebonding agent that holds the printedetch to the circuit card. Use the recom-mended soldering iron, or equivalent.

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TM 11-5820-922-40-1

4. Use solder sparingly. Excess 6. Check the work. Be certain thatsolder should be removed with the the solder joint is firm and clean.recommended solder-removing tool, orequivalent. 3-19. CIRCUIT CARD REPAIR TOOLS AND

MATERIALS. For repair to the circuit5. Clean and tin the leads of a com- cards, the tools listed in table 3-1 and

ponent before soldering the component to the materials listed in table 3-2 arethe board. recommended.

TABLE 3-1. RECOMMENDED TOOLS

Tool Manufacturer Part Number

Bench repair center Pace Inc. PRC-350C

Kit, tool, electronic ... TK-100/G

Maintenance kit, printed circuit ... MK 984/A

Clamps, small ... ...

Coining tool Erem 5174

Oven capable of maintaining ...150 ±10 °F

...

Parallel gap welding machine:Power supply ... MCW 550Welding head ... VTA66

TABLE 3-2. RECOMMENDED MATERIALS

Material Manufacturer Type

Acetone solvent (acetone) ... ...

Epoxy compound (Epon packaged in Frey Engineering MIL-I-16923a plastic syringe, DTA catalystin a glass vial)

Epoxy adhesive

Epoxy adhesivefrozen pre-mixadhesive kit)

Narmco 3135A and B kit

kit, flexible, Narmco 3135(Narmco

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TABLE 3-2. RECOMMENDED MATERIALS (Continued)

Material Manufacturer Type

Epoxy adhesive kit, flexible,18 gram (Narmco adhesive kit)

Epoxy adhesive kit, flexible,1 pint (Narmco adhesive kit)

Glass beads, 0.003-inch diameter

Hook-up wire and cable, 26 gage,insulated electrical (copperjumper wire)

Isopropyl alcohol

Masking tape

Polyurethane conformal coatingcompound

Sandpaper, 80 to 180 grit

Soldering flux

Solder, rosin-cored, 1/32 inch

Solder-wick

Solvent

Solvent, TMC (Freon TMCsolvent)

Thermally conductive adhesive

Tin-coated wire, 34 gage,uninsulated, electrical

Toluene solvent (toluene)

Narmco

Narmco

Superbrite

...

...

...

Conap, Inc.

...

Kester

Kester

Solder Removal Co.

Conap, Inc.

Freon

Wakefield

...

...

3135-MRO 40-0965

3135-MRO 40-0962

...

4297780-49,LW-C-26-1-J-9

...

...


...

197

44

-3-500


MRO 55

Delta Bond 152

4297869-25

...

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3-20. ETCH REPAIR. The solder-platedcopper or gold-plated copper conductors(etch) bonded to the surface of the cir-cuit cards can be damaged when mishan-dled or when a component failure causescurrent flow that exceeds the current-carrying limits of the etch. Certaintypes of damage to the etch can berepaired by using the appropriate repairtechniques. Scratches or gouges on theetch can be repaired by soldering. Sol-dering is also used to repair voids orpinholes in the etch. Breaks or cuts inthe etch can be repaired by bridging thedefect with a new section of etch.Lifted, raised, or unbonded etch can berepaired by pressing the etch againstthe card surface and encapsulating thedefect with epoxy adhesive. Damagedplated-through holes or eyelets arerepaired by inserting and soldering aneyelet. To repair damaged etch, per-form the procedures of the followingparagraphs that apply to the type ofdamage to be repaired.

3-21. Repair of Scratched, Gouged,Voided, or Pinholed Etch. Scratched,gouged, voided, or pinholed etch faultscan be repaired by performing the fol-lowing steps:

1. With an X-acto knife, scrape thepolyurethane coating from the area ofthe circuit card to be repaired. Becareful not to cause further damage tothe etch.

2. Flatten any burrs that exist onthe defective area of the etch by usingthe back of the recommended diagonalcutting pliers, or equivalent.

3. Use a brush to apply solderingflux to the etch where defect exists.

4. Use the soldering iron to applysolder to the defect. Use soldersparingly.

5. Inspect the repair to be certainthat the damaged area has been bridgedby the solder.

6. Encapsulate the worked area by themethod described in paragraph 3-33.

3-22. Repair of Broken Gold-PlatedCopper Etch. Broken or cut gold-platedcopper etch can be repaired by perform-ing the following steps:

1. With an X-acto knife, scrape thepolyurethane coating from the area ofthe circuit card to be repaired. Becareful not to cause further damage tothe etch.

2. Cut out a section approximately1/2 inch longer than the area to berepaired from a strip of gold-platedcopper ribbon (etch material).

3. Tin the new piece of etch mate-rial; use solder sparingly.

4. Position the new etch materialover the damaged area so that it over-laps by 1/8 inch and hold it in placewith an orange stick.

5. Touch the soldering iron to oneend of the new etch material until thesolder flows to the damaged etch at thatend.

6. Use an orange stick to smooth outthe new etch material, work toward theunsoldered end; hold the new etchmaterial firmly in place with the orangestick, cut off the surplus, and allowapproximately 1/8 inch for overlap.

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7. Touch the soldering iron to thefree end of the new etch material untilthe solder flows to the damaged etch atthat end.

WARNING

Isopropyl alcohol is flammable.Keep away from heat and openflame. Vapors may be harmful.Use with adequate ventilation.Avoid prolonged or repeatedbreathing of vapor. Avoideye contact. Do not takeinternally.

8. Remove excess soldering flux withisopropyl alcohol.

9. Apply masking tape around therepaired area. Allow approximately1/16-inch gap between the circuit andtape on both sides and 1/8 inch at theends.

WARNING

Adhesives are irritating to theskin and eyes upon contact, andmay emit harmful vapor. Useonly with adequate ventilation.Avoid all skin and eye con-tact. Use protective clothingsuch as rubber gloves, apronand eye protection. Wash offimmediately any accidentallycontaminated skin area. Handwashing facilities and eyewash fountain should be pro-vided. Do not take internally.

10. Mix a small quantity of epoxyadhesive in equal parts on a smoothpiece of glass or hard plastic; mix thetwo components thoroughly.

11. Seal the repaired area by applyinga thin, smooth bead of the mixedadhesive over and around the edges ofthe circuit in a neat and workmanlikemanner.

12. Allow the adhesive to set 1 hourat room temperature.

13. Remove masking tape and removesurplus adhesive by scraping lightly.

WARNING

Handling hot items presents aserious injury potential.Asbestos gloves are required.

14. Cure the repair in an oven for 1hour at 150 ±10 °F or allow it to standat room temperature for 24 hours.

WARNING

Polyurethane contains flam-mable solvents and toxicdiisocyanates. Keep awayfrom heat and open flame.Vapors or mists are harmful:Complete body protection,including entire head, isrequired to prevent skin oreye irritation from contactwith the paint or its vaporsor mists. Respirator protec-tion is required, usually anair-supplied hood, duringmixing, curing, and applica-tion. Use this paint only withthe protection requirements asspecified above. Suitableflushing facilities must beprovided for immediate cleanwater flushing or any acci-dental skin or eye contact.Do not take internally.

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15. Encapsulate the worked areawith polyurethane coating by themethod described in paragraph 3-33.

3-23. Repair of Raised or UnbendedGold-Plated Copper Etch. Raised orunbended gold-plated copper etchcan be repaired by performing thefollowing steps:

1. Determine the hole diameterrequired for the new eyelet andselect an eyelet of similar size.

WARNING

Drilling operations createmetal chips which may enterthe eyes and cause seriousinjury. Eye protection isrequired.

2. If the hole is plated-through, drill the hole to accom-modate the new eyelet. Be carefulnot to raise the etch while dril-ling. If the hole has an eyelet,remove the defective eyelet.

3. Use the eyelet press and diesto insert and form the new eyelet;allow approximately 0.01 inch ofetch to extend beyond the eyeletrim. Allow clearance under both ofthe formed heads so that solderflow under and around the formedheads will not be impaired.

4. Insert a round toothpick, orequivalent, in the eyelet hole toprevent solder from entering thehole.

5. Apply soldering flux with abrush to the eyelet and surroundingetch.

6. Use a soldering iron to applysolder to the eyelet and to thesurrounding etch on both sides ofthe circuit card.

WARNING

Isopropyl alcohol is flammable.Keep away from heat and openflame. Vapors may be harmful.Use with adequate ventilation.Avoid prolonged or repeatedbreathing of vapor. Avoid eyecontact. Do not take internally.

7. Remove the soldering flux andclean the circuit card with iso-propyl alcohol.

3-24. REPLACEMENT OF A LIFTED PAD.Lifted pads (circular etch surround-ing either eyelets or plated-through holes that have raised fromthe board) can be replaced by per-forming the following steps:

1. Remove the lifted pad. Ifthe hole has an eyelet, remove theeyelet first.

WARNING

Toluene is flammable. Keepaway from heat and open flame.Vapors are harmful. Use onlywith adequate ventilation.Avoid prolonged or repeatedbreathing of vapor. Avoid con-tact with skin and eyes. Donot take internally. Complywith air pollution controlrules concerning photochemi-cally reactive solvents.

2. Clean the area from which thedefective pad was removed with aclean cloth moistened with toluene.

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WARNING

Adhesives are irritating tothe skin and eyes upon con-tact, and may emit harmfulvapor. Use only with ade-quate ventilation. Avoidall skin and eye contact.Use protective clothing suchas rubber gloves, apron andeye protection. Wash offimmediately any accidentallycontaminated skin area.Hand washing facilities andeye wash fountain should beprovided. Do not takeinternally.

3. Apply a thin, smooth coat ofclear epoxy adhesive to the areafrom which the defective pad wasremoved.

4. Place the new pad, as nearlyas possible, in the exact positionof the defective pad. Insert around, pointed toothpick in thehole to help in alignment. Pressthe pad firmly in place with anorange stick while gently removingthe toothpick from the hole.

5. Allow the epoxy adhesive toset for 1 hour at room temperature.

6. Carefully remove surplusadhesive by using a clean clothdipped in toluene or other suitablesolvent.

WARNING


7. Cure the repaired pad in anoven ±10 °F or let it stand at roomtemperature for 24 hours.

8. If the repair appears wet andwell bonded, install and solder aneyelet as described in steps 3 thru7 of paragraph 3-23.

3-25. REMOVAL OF BONDED PARTS. Apart that has been bonded to a cir-cuit card (with an epoxy adhesiveor similar compound) can be removedafter the leads have been clippedor unsoldered by breaking the defec-tive part or by applying heat tothe bonding compound. The methodto be used depends on the type ofpart and its location. If a defec-tive part cannot be removed byheat, cut or break the part awayfrom the bonding compound. In somecases, the part to be replaced isso closely positioned between otherparts that one lead must be cutclose to the body of the defectivepart to permit the application of aprying tool. Wherever possible,cut the defective part withdiagonal cutting pliers.

Never apply excessive pressureagainst a circuit card.

3-26. Regardless of the toolemployed (round-pointed or spadetype), great care must be exercisedin its use to prevent the circuitcard or other parts from beingdamaged or broken. Apply the pointof the tool against the bondingcompound and between the part andthe circuit card. Use the tool sothat it works away the bondingcompound from the part to be brokenuntil enough has been removed forthe tool to exert pressure againstthe part. Keep the leverage sur-face area of the tool flat againstthe surface of the circuit card toprevent the tool from gouging orbreaking the board.

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3-27. REMOVAL OF SOLDERED COMPONENTSHAVING AXIAL LEADS. Components withaxial leads that are soldered in placeon the circuit card may be removed byperforming the following steps:

1. Use diagonal cutting pliers to cutthe leads of the component part close tothe component. Carefully straighten theend that extends through each hole sothat the lead may be easily withdrawn.

2. Use a vacuum resoldering unit, ifavailable, to remove the solder fromeach lead on the component. If a vacuumresoldering unit is not available, exerta slight pressure and apply the tip ofthe soldering iron to the tip of thelead. Keep the soldering iron away fromthe circuit etch. As the lead endabsorbs heat, the solder will melt andthe lead will break away from its junc-tion with the circuit etch. Remove thesoldering iron immediately and quicklypull the lead free. Use the solder-removing tool to remove excess solder.Do not force or twist the lead to removeit from the circuit card.

3. Remove the component from thecircuit card.

3-28. REMOVAL OF SOLDERED COMPONENTSHAVING RADIAL LEADS. Components withradial leads that are soldered in placeon the circuit card may be removed bythe procedure described in paragraph3-29 if the leads are accessible on thecomponent side of the circuit card. Ifthe leads of the component are notaccessible on the component side of thecircuit board, the component may beremoved by performing the followingsteps:

1. Use a vacuum resoldering unit, ifavailable, to remove the solder fromeach lead on the component. If a vacuumresoldering unit is not available, exerta slight pressure and apply the tip ofthe soldering iron to the tip of thelead. Keep the soldering iron away fromthe circuit etch. As the lead absorbsheat, the solder will melt. When the

solder has melted, in and around thelead hold, quickly remove the solderwith the solder-removing tool. Repeatthis procedure for each lead associatedwith the component to be removed.

2. Remove the component from thecircuit card.

3-29. REMOVAL OF TRANSISTORS. Thetransistor connection points in a givencircuit may not be keyed. Therefore,when replacing a transistor, it is pos-sible to insert the replacement transis-tor backwards to reversing the emitterand collector leads. For this reason,before the transistor is unsoldered fromthe circuit, identify the emitter andcollector terminals in the circuit.Mark the emitter terminal connectionpoint in the circuit with a pencil, apiece of chalk, or a crayon beforeremoving the transistor. The transistormay then be removed.

3-30. SOLDERED COMPONENT REPLACEMENT.Horizontally mounted components rated atless than 1 watt and with pigtail leadswhich are inserted in plated-througheyelets or in unsupported holes shouldbe mounted flush with the board surface.Components rated at 1 watt or moreshould be mounted with 1/16-inchclearance between the component and thesurface of the board.

3-31. COMPONENT REPLACEMENT IN EYELETS.Components may be replaced in circuitcards which have eyelets by performingthe following steps:

NOTE

See paragraph 3-30 for compo-nent clearance requirements.

1. Make certain that all the poly-urethane coating has been removed fromthe pads on both sides of the circuitcard.

2. Apply the well-tinned tip of thesoldering iron as close as possible tothe eyelet-component lead intersection.

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TM 11-5820-922-40-1

3. Feed rosin-cored solder to thepad-eyelet junction. When the solderflows, follow the flow around the eye-let with the solder until the entirejoint is covered. Remove the ironimmediately. Use as small an amount ofsolder as is practical and still coverthe entire joint.

4. Allow the soldered joint to coolat least 5 seconds without disturbingthe joint, as any disturbance duringsolidification may cause a fracture or acold-solder joint.

5. On the reverse side of the cir-cuit card, trim the lead as flush aspossible.

6. Repeat steps 2 thru 4 for eachlead on the component.

7. Encapsulate the component usingthe method described in paragraph 3-33.

3-32. COMPONENT REPLACEMENT IN PLATED-THROUGH HOLES. Components may bereplaced in plated-through holes byperforming the following steps.

1.

NOTE

See paragraph 3-30 for compo-nent clearance requirements.

Make certain that all the poly-urethane coating has been removed fromthe pads on both sides of the circuitcard.

2. Apply the well-tinned tip of thesoldering iron as close as possible tothe component lead-pad junction.

3. Feed rosin-cored solder to thecomponent lead-pad junction opposite thesoldering tip. When the solder flows,follow the flow around the componentlead-pad junction with the solder untilthe entire joint is covered. Remove theiron immediately. Use as small anamount as is practical and still coverthe entire joint.

4. On the reverse side of the board,trim the lead as flush as possible.

5. The opposite side of the boardneed not be soldered if the entire innersurface of the hole has been soldered.

6. Repeat steps 2 thru 5 for eachlead on the component.

7. Encapsulate the component by themethod described in paragraph 3-33.

3-33. REPAIR OF POLYURETHANE CONFORMALCOATING. The polyurethane conformalcoating seals (encapsulates) the circuitcard and components from moisture anddust. The coating should not be reliedupon to impart mechanical strength forhandling. Discontinuities in the poly-urethane conformal coating, such asholes caused by test probes, areasscraped for component replacement oretch repair, burned areas caused by thesoldering iron , and discontinuitiescaused by an uncoated replacement com-ponent itself may be repaired by per-forming the following steps.

WARNING

Solvents used in this procedureare flammable and must be keptfrom open flame, heat, andsparks. Keep containers tightlyclosed and store them in a coolplace when not being used. Thesolvent must be used only in anadequately ventilated environ-ment. Avoid breathing vaporsand repeated contact with skin.Clean hands thoroughly beforesmoking, eating, or drinking.

1. Prepare a mixture of polyurethaneconformal coating by following the manu-facturer’s instructions. Solvent may beadded as required.

2. Apply a thin, smooth, uniformcoating with a small brush (1/2 inch) toall areas requiring coverage.

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3.

11-5820-922-40-1

WARNING


Cure the coating in an oven set at165 °F for 1-1/2coating stand at24 hours.

3-34. REPAIR OF

hours or by letting theroom temperature for

DAMAGED FIBER GLASSEPOXY PARTS. Damaged fiber glass partsmay be repaired by performing the fol-lowing steps.

NOTE

For parts other than circuitboards, no more than 10 per-cent of the surface area shallbe repaired.

1.

NOTE

For circuit boards, the areato be repaired shall notexceed 1 square inch; themaximum depth of repair shallnot exceed 50 percent of theoriginal laminate thickness;misdrilled holes which do notinterfere with the function ofthe circuit board shall remainunrepaired; and minor crackswhich do not go through theentire thickness of thelaminate may be repairedaccording to the followingprocedure.

Sand or scrape the area to berepaired using 80 to 180 grit sandpaperor a scraper to remove all traces ofburned or charred laminates. In thecase of a minor crack, scrape to theentire depth of the crack.

2. Wipe the surface at least twicewith a clean cloth wet with acetone andallow to dry thoroughly.

3-14

3. Using epoxy compound, empty theglass vial of catalyst and the syringeof Epon into the aluminum cup and mix toa complete homogeneous condition.

NOTE

The pot life of the epoxy mix-ture is approximately 30 min-utes. All material not usedwithin 30 minutes must bediscarded.

4. Immediately apply the epoxy mix-ture to the damaged area making sure tothoroughly wet the area to be repaired.

5. Apply sufficient material to coverthe entire area to be repaired. Add asmall “crown” of material to allow forshrinkage.

WARNING

6.cure


Allow the repaired area to airfor 16 hours minimum or heat cure

in an oven for 1 hour at 150 ±10 °F.

7. Sand or scrape the crown of therepair until the repair is relativelysmooth and even with the originallaminate.

3-35. MODIFICATION OF SOLDER-PLATEDPRINTED WIRING CIRCUIT CARDS. Solder-plated printed wiring circuit cards maybe modified by brazing gold-platedcopper wire to solder-plated copperconductors. The procedural steps are asfollows.

NOTE

No more than two modificationjumper wires are allowed to bebrazed on one printed wiringpad. Joints are not allowedon printed circuit conductorsthat are less than the widthof the coined (flattened)jumper wire end.

TM 11-5820-922-40-1

1.

NOTE

This procedure may be per-formed only by personnelqualified as parallel gapwelding operators.

Technical personnel familiar withthe functionmine the twowire must be

2. Bend a

of the circuit must deter-points to which the jumperattached.

30-gage insulated gold-plated solid-copper jumper wire to thedesignated tabs. Cut to required length.

3. Remove the insulation for a dis-tance between 6 and 7 millimeters (1/4and 5/16 inch) from each end of the wire.

SINGLE WIRE

Weld duration 8 - 10 ms

Weld voltage 0.63 - 0.66v

Weld force

4. With the coining tool, coin(flatten) the gold-plated copper wireends to approximately 0.13 millimeter(0.005 inch) thickness by 2.54 milli-meters (0.100 inch) long by 0.38 milli-meter (0.015 inch) wide (fig 3-6).

5. Braze the coined (flattened) wireto the printed circuit conductor padusing the parallel gap welding machineaccording to the following schedule.Single wires (fig 3-7) or double wires(fig 3-8) can be brazed to one circuitpad.

6. Encapsulate the jumper wire asdescribed in steps 7 thru 10.

DOUBLE WIRE

1.3 - 2.3 kg (3-5 lb)

Electrode gap 0.38 - 0.50 mm(0.015 - 0.020

Use Freon with good ventila-tion. Avoid prolonged orrepeated breathing of vapor.Avoid contact with skin andeyes. Do not take internally.

7. Clean the area to be encapsulated,using Freon TMC solvent.

WARNING

Adhesives are irritating to theskin and eyes upon contact, andmay emit harmful vapor. Useonly with adequate ventilation.Avoid all skin and eye contact.Use protective clothing such asrubber gloves, apron and eyeprotection. Wash off immedi-ately any accidentally con-

8 - 10 ms

0.66 - 0.68V

1.3 - 2.3 kg (0-5 lb)

0.38 - 0.50 mmin.) (0.015 - 0.020 in.)

taminated skin area. Hand wash-ing facilities and eye washfountain should be provided.Do not take internally.

8. Use any one of Narmco Epoxy Adhe-sive Kits No. 3135 listed in table 3-2.If the frozen premix kit is used, allowit to thaw to room temperature prior touse. If either of the two-part kits isused, mix approximately equal quantitiesof Part A and Part B, using a disposablealuminum cup for mixing. Mix thoroughly.

9. Bond the jumper wire to theprinted wiring board by applying a spotof adhesive (prepared in step 8) to aminimum diameter of 6.35 millimeters(1/4 inch) at intervals of 5 centimeters(2 inches). It is not necessary toencapsulate the brazed joint. Avoidapplying adhesive to any area that maybe subsequently soldered.

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TM 11-5820-922-40-1

Figure 3-6. Coined 30-Gage Wire End

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Figure 3-7. Single-Wire Attachment to Printed Circuit Pad

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TM 11-5820-922-40-1

Figure 3-8. Double-Wire Attachment to Printed Circuit Pad

3 - 1 8

TM 11-5820-922-40-1

WARNING


10. Allow the adhesive to gel for aminimum of 1 hour at room temperatureand then bake for 1 hour minimum at atemperature of 150 ±10 °F, or allowadhesive to air dry at room temperaturefor 24 hours. If adhesive is ovencured, allow it to cool at room temper-ature after removal from the oven.

3-36. REPAIR OF BROKEN THERMAL MOUNTINGPLATE POWER OR GROUND TABS. Brokenthermal mounting plate power or groundtabs may be repaired using copper jumperwire by performing the following steps:

1. Technical personnel familiar withthe function of the circuit must deter-mine the two points to which the copperjumper wire is to be attached.

2. Form the 26-gage insulated copperjumper wire to the designated points andcut to the required length (fig 3-9).

3. Strip a distance of 1/4 to5/16 inch from the wire ends.

CAUTION

The areas to be soldered mustbe heated until the solderflows. Overheating can dam-age the board or nearby com-ponents. The wires beingsoldered must not be allowedto move in relation to oneanother until the solder hascompletely solidified.

4. Solder each end of the jumper wireto the selected pads.

5. Encapsulate the jumper wire asdescribed in steps 6 thru 8.

WARNING

Adhesives are irritating to theskin and eyes upon contact, andmay emit harmful vapor. Useonly with adequate ventilation.Avoid all skin and eye contact.Use protective clothing such asrubber gloves, apron and eyeprotection. Wash off immedi-ately any accidentally contami-nated skin area. Hand washingfacilities and eye wash foun-tain should be provided. Donot take internally.

6. Use any one of the Narmco EpoxyAdhesive Kits No. 3135 listed in table3-2. If the frozen premix kit is used,allow it to thaw to room temperatureprior to use. If either of the two-partkits is used, mix small, approximatelyequal, quantities of Part A and Part B,using a disposable aluminum cup formixing. Mix thoroughly.

7. Bond the jumper by applying auniform coat of adhesive over the entirelength of themore adhesivepletely cover

jumper wire. Do not usethan necessary to com-the jumper wire.

WARNING


8. Allow the adhesive to gel for1 hour minimum at room temperature andthen bake for 1 hour minimum at tem-perature of 150 ±10 °F or allow adhesiveto air dry at room temperature for24 hours minimum. If adhesive is ovencured, allow it to cool at room temper-ature after removal from the oven.

3-19

Figure 3-9.

TM 11-5820-922-40-1

3-20

TM 11-5820-922-40-1

3-37. REPAIR OF CONCEALED SHORT CIR-CUITS IN PRINTED WIRING ASSEMBLIES.Concealed short circuits in printedwiring assemblies may be repaired byperforming the following steps.

NOTE

Jumper wires shall be installedon the rear side of the assem-bly whenever possible, but ifnecessary, jumper wires may beinstalled on the component sideprovided they do not cross overthe top of a component.

NOTE

The repair of concealed shortcircuits involves three steps:(1) isolation of the shortedarea, (2) cutting the conduc-tors at each side of the short,and (3) restoring the continu-ity by the installation ofjumper wires.

1. Technical personnel familiar withthe function of the circuit must deter-mine the area of the short circuit, theconductors to be cut, and the jumperwires to be installed.

2. Cut and remove a bit of circuitry1/8 inch long in each shorted conductoron each side of the short.

3. Form 26-gage insulated copperjumper wires between the designatedpoints on each side of the short circuitarea.

4. Strip the ends of each jumper wirea distance of 1/4 to 5/16 inch.

CAUTION

The areas to be soldered mustbe heated until the solderflows. Overheating can damagethe board or nearby components.

NOTE

If there is an eyelet orplated-through hole not beingused for a component termina-tion, it may be used as ajumper wire termination.

5. If the end of any one of thejumper wires is to be attached to anetched conductor, plate the stripped endof the wire on the conductor in a direc-tion parallel to the etched conductorand solder in place. Then solder theends of the other jumper wires in place.

6. Encapsulate each of the jumperwires as described in steps 7 thru 10.

WARNING

Use Freon with good ventila–tion. Avoid prolonged orrepeated breathing of vapor.Avoid contact with skin andeyes. Do not take internally.

7. Clean the areas to be encapsulatedusing Freon TMC solvent. Be sure thatall traces of rosin flux are removed.

WARNING

Adhesives are irritating to theskin and eyes upon contact, andmay emit harmful vapor. Useonly with adequate ventilation.Avoid all skin and eye contact.Use protective clothing such asrubber gloves, apron and eyeprotection. Wash off immedi-ately any accidentally contami-nated skin areas. Hand washingfacilities and eye washingfountain should be provided.Do not take internally.

8. Use any one of the Narmco EpoxyAdhesive Kits No. 3135 listed in

3-21

TM 11-5820-922-40-1

table 3-2. If the frozen premix kit isused , allow it to thaw at room temper-ature prior to use. If either of thetwo-part kits is used, mix approximatelyequal quantities of Part A and Part B,using a disposable aluminum cup formixing. Mix thoroughly.

9. Bond the jumper wires to the cir-cuit board by applying a uniform coatingof adhesive over the entire length ofeach jumper wire. Do not use more adhe-sive than necessary to completely coverthe jumper wires.

10. Allow the adhesive to gel for1 hour minimum at room temperature.Then bake for 1 hour minimum at a tem-perature of 150 ±10 °F, or allow theadhesive to dry at room temperature for24 hours minimum. If adhesive is ovencured , allow it to cool at room temper-ature after removal from the oven.

3-38. REPAIR OF THERMAL MOUNTING PLATEON HIGH-DENSITY PRINTED WIRING BOARDS.Thermal mounting plate on high-densityprinted wiring boards may be repaired byperforming the following steps:

1. Carefully clean out all the looseadhesive from the area between thelifted thermal mounting pad and theprinted wiring board using an orangestick, or equivalent hand tool.

WARNING

Adhesives are irritating to theskin and eyes upon contact, andmay emit harmful vapors. Useonly with adequate ventilation.Avoid all skin and eye contact.Use protective clothing such asrubber gloves, apron and eyeprotection. Wash off immedi-ately any accidentally contam-inated skin area. Hand washingfacilities and eye wash foun-tain should be provided. Donot take internally.

3. Any one of the Narmco Epoxy Adhe-sive Kits No. 3135 listed in table 3-2may be used as the repair adhesive. Ifthe frozen premix kit is used, allow itto thaw at room temperature prior touse. If either of the two-part kits isused , mix small, approximately equal,quantities of Part A and Part B, using adisposable aluminum cup for mixing. Mixthoroughly.

4. Carefully apply a thin smooth coatof adhesive under the thermal mountingpad. Do not use more adhesive thannecessary.

5. Carefully clamp the thermal mount-ing plate to the board.

6. Allow the adhesive to gel for atleast 1 hour at room temperature.

WARNING

Use Freon with good ventila- WARNINGtion. Avoid prolonged orrepeated breathing of vapor. Handling hot items presents aAvoid contact with skin and serious injury potential.eyes. Do not take internally. Asbestos gloves are required.

2. Clean the area to be repaired withFreon TMC solvent to remove residual 7. Bake the board in an oven at 150surface contaminants. ±10 °F, for at least 1 hour.

3-22

TM 11-5820-922-40-1

8. Remove the board from the oven andallow it to cool to room temperature.Remove the clamp(s).

3-39. REPAIR OF DEFECTIVE PLATED-THROUGH HOLE. Defective plated-throughholes can be repaired by performing thefollowing steps.

NOTE

If there should be a componentplaced in such a manner as tointerfere with the performanceof this repair, remove thatcomponent according to theprocedure contained in para-graph 3-27 or paragraph 3-28.Handle this removed componentwith care because it may bereinstalled upon the com-pletion of this repair.

1. Cut a length of 34-gage uninsu-lated tin-coated wire from 50 to 100millimeters (2 to 4 inches) long andpass it through the defective plated-through hole. If the wire will not passthrough the hole, due to solderbuild-up, the hole may be cleared withthe use of a vacuum resoldering unit.

2. Hold one end of the wire againstone side of the circuit card and pullthe other end taut and down against theother side of the circuit card, beingcareful to avoid aligning the wire withany circuit traces emerging from the pad.

3. Turn the circuit card over andrepeat step 2 for the opposite side.

6. Using an X-acto knife, very care-fully cut down into the wire just at, orahead of, the point where it emergesfrom the solder.

NOTE

The wire shall not extend pastthe periphery of the pad towhich it is soldered.

7. Grasp the free end of the wire andlift it slowly so that it separates atthe cut produced in step 6.

8. Turn the circuit card over andrepeat steps 6 and 7 for the other sideof the repair.

9. Apply a small amount of solderingflux to each side of the repair, andusing the soldering iron touch up thesolder joints to cover any of the copperwire exposed by the trimming of theleads.

WARNING

Isopropyl alcohol is flammable.Keep away from heat and openflame. Vapors may be harmful.Use with adequate ventilation.Avoid prolonged or repeatedbreathing of vapor. Avoid eyecontact. Do not takeinternally.

4. Using solder, the soldering iron,and the flux, carefully solder the wire 10. Clean the repaired area withto the pad using a minimum amount of isopropyl alcohol.solder.

5. Turn the circuit card over and 11. If a component has been removed inrepeat step 4 as required. order to accomplish this repair, and if

it is visually and mechanically sound,CAUTION replace that component according to the

procedure in paragraphs 3-30, 3-31, orDo not cut down into the cir- 3-32. If the component is defective,cuit card pad when trimming the replace it with an identical newwire. component.

3-23

TM 11-5820-922-40-1

3-40. GENERAL.

SECTION II

CLEANING AND EXAMINATION

CAUTION

3-41. This section contains generalinformation for the cleaning andinspection of the amplifier-converter.The term “cleaning” means all those proc-esses by which dirt or contaminants areremoved from the equipment without caus-ing damage to the equipment or danger topersonnel. The term “examination” meansall those processes by which the equip-ment is compared or measured against anacceptable standard for cleanliness,mechanical and electrical (electronic)condition, serviceability, and perform-ance capability.

3-42. CLEANING.

WARNING

When using a compressedairjet, use eyeshields.

WARNING

When using solvents, provideproper ventilation, avoid pro-longed contact, and do notsmoke. Solvents must meet allpertinent specifications regard-ing toxicity, flammability, andallergenic effect.

CAUTION

Compressed air must be clean,dry, and at a maximum pressureof 28 psi. Do not overlookthe force of the airjet whencleaning delicate parts.

Certain solvents will damageinsulation. Do not use sol-vents chemically similar to"Chlorothene” or “Glyptal” toclean module connectors. Useonly denatured alcohol forthis purpose.

3-43. EXTERNAL. Clean the exterior ofthe amplifier-converter by using anairjet. If accumulated dirt cannot beremoved by the airjet alone, use amedium-stiff camel’s hair or similarbrush to aid the airjet action.

3-44. An approved solvent or detergentmay be used to remove grease, oil, orother contaminants, provided that it isnot allowed to run into the insulatedsleeving of cable assemblies and wiring.All solvents and detergents tend tocause binding if allowed to seep intoshaft bearings or other moving parts.

3-45. INTERNAL. The interior of theamplifier-converter and separatedisassembled parts may be cleaned byusing one or more of the followingmethods:

1. Clean, dry, lint-free cloth.2. Airjet and brush.

3-46. CORROSION CONTROL. The followingperiodic checks and services arerequired for prevention and control ofcorrosion and fungus of the amplifier-converter.

1. Inspect the exterior of theamplifer-converter and each unit forcorrosion and fungus (particularlyaround the controls and connectors).

3-24

TM 11-5820-922-40-1

2. Remove all corrosion and fungus e. There is no binding, sticking,with a cloth and/or brush moistened in or looseness of moving mechanical parts.cleaning solvent.

3. Repaint all treated areas imme- f. All electrical/electronic partsdiately upon removal of corrosion to are correctly oriented for clearancesalleviate the reoccurrence of corrosion and lead shortness. Printed circuitbuild-up. boards are not under strain due to

incorrect mounting.3-47. EXAMINATION.

3-48. GENERAL . Examination of the g. Detection of blackened, over-amplifier-converter includes a visual heated, broken, or missing electrical/inspection, troubleshooting, and a per- electronic components and parts.formance test , all of which should beperformed when a fault has occurred orrepair work has been made on an h. Detection of missing or brokenamplifier-converter. hardware, loose mountings, and missing

mechanical parts.3-49. Visual Inspection. Visualinspection of the amplifier-converteris separated into two distinct areas: i. No short circuits or grounds arecompletely assembled and unassembled. caused by module case or cover.

1. Completely Assembled VisualInspection. This inspection is made toensure that all external hardware ispresent and correct.

2. Unassembled Visual Inspection.The unassembled visual inspectionincludes the following:

a. Observance of critical posi-tioning or adjustment of all mechanicaland electrical/electronic parts.

b. All required hardware is usedand correct.

c. All required parts are used andcorrect.

d. All required wiring, soldering,and sleeving is correct. This includescorrect "dressing" arrangement of wireharnesses and cables, etc. Detection of

3-50. Troubleshooting Inspection. Theobjective of troubleshooting is tolocate the site of a malfunction, afterwhich repair can be carried out. Thus,troubleshooting is an inspection processwhich determines how a malfunctioningitem of equipment can be made service-able. However, in many cases, this proc-ess may require disassembly, and therepair may actually be carried out dur-ing troubleshooting (to prove the cor-rectness of the troubleshooting diag-nosis). In this way, troubleshootinginspection also identifies the replace-ment time. The flowcharts provided inthe maintenance chapters include per-formance tests and troubleshootingtechniques.

3-51. Performance Test. A perform-ance test for the complete amplifier-

frayed, burned, shorted, or broken cables, converter and for the individual circuitwiring, and dry-jointed, shorted, or cards is included in the appropriategrounded solder connections. chapters.

3-25

TM 11-5820-922-40-1

SECTION III

FABRICATION OF TEST CABLES

3-52. GENERAL. converter circuit cards. Necessaryinformation for fabrication of the test

3-53. Fabrication of test cables is cables and adapters is shown in figurerequired for the performance test of the 3-10. Figures 3-11 and 3-12 show howamplifier-converter and performance/ the VM/RE and audio cables arefault isolation tests of the amplifier- fabricated.

3-26

T M 1 1 - 5 8 2 0 - 9 2 2 - 4 0 - 1

Figure 3-10. Fabrication of Test Cables and Adapters.

3 - 2 7 / ( 3 - 2 8 b l a n k )

T M 1 1 - 5 8 2 0 - 9 2 2 - 4 0 - 1

Figure 3-11. VM/RE Cable W1

3-29 / (3 -30 b lank)

T M 1 1 - 5 8 2 0 - 9 2 2 - 4 0 - 1

Figure 3-12. Audio Cable W2

3 - 3 1 / ( 3 - 3 2 b l a n k )

TM 11-5820-922-40-1

SECTION IV


3-54. GENERAL.

3-55. Performance test and trouble-shooting of the amplifier-converter andits circuit cards requires a known-goodamplifier–converter as a test bed. Thecircuit card or unit under test (UUT)replaces the known-good circuit card ofthe test bed amplifier-converter, andis connected to the test bed by a fabri-cated extender cable. (This appliesonly to the amplifier-squelch and TTY-FSK converter. The EMI filter, rfifilter, and audio filter, because oftheir lack of sophisticated circuitry,are tested statically.)

3-56. PERFORMANCE TEST ANDTROUBLESHOOTING .

symbol at the end of the test indicatessuccessful completion of the test. Thetroubleshooting procedure is completedwhen a fault indication block is reached.Once a fault is corrected, the perform-ance test is resumed at the point wherethe first fault indication occurred. Ifa flowchart is extended to another sheet,the continuation symbol is used.

3-59. TEST AND TROUBLESHOOTING REFER-ENCE DATA. The performance test flow-charts are used in conjunction with thesupporting data below. Figure 3-14depicts the arrangement of maintenanceinformation contained in each mainte-nance chapter.

1. Disassembly and Reassembly Proce-3-57. The performance test flowcharts dures. These procedures provide theprovide the necessary procedures and information necessary to remove andinformation to completely test the replace a unit under test.amplifier-converter and applicable cir-cuit cards. The flowcharts also providetroubleshooting procedures as an aid in

2. Performance Test Setup Diagrams.

fault isolating to a component or groupThe test setup diagrams show what testequipment is required for the perform-

of components if the UUT does not pass aperformance test.

ance test and troubleshooting, and howto connect the test equipment to the

3-58. FLOWCHARTS (Figure 3-13). Theperformance test procedure path on theflowcharts is indicated by a heavy flowline. The procedure begins at the bub-ble symbol that reads “unit under test.”Next, the initial setup block referencesapplicable disassembly and reassemblyInstructions, a test setup diagram, andprovides initial switch settings requiredfor the test. The initial setup block

unit under test.

3. Alignment Procedures. The align-ment procedures are performed when speci-fied in the troubleshooting procedures.They are usually required during trouble-shooting to ensure the unit under testis properly aligned before determiningfaulty components.

is followed by a series of procedural 4. Junctional Block Diagrams. Theblocks which contain actions required to functional block diagrams of chapter 2produce a result, and decision blocks may be used as an aid to troubleshootingwhich ask whether the desired result in conjunction with the flowcharts.occurred. If the desired result hasoccurred, the “yes” pathway is followed; 5. Schematic Diagrams. The sche-if the desired result did not occur, the matics for the “Unit Under Test” are“no” pathway is followed for the trouble- used to aid in identifying suspectedshooting procedure. The “Test Passed” faulty components. For example, if the

3-33

TM 11-5820-922-40-1

Figure 3-13. Flowchart Symbology

3-34

SEC I

SEC II

SEC III

SEC IV

SEC V

SEC VI

TM 11-5820-922-40-1

Figure 3-14. Maintenance Chapter Construction

3-35

TM 11-5820-922-40-1

fault block on the troubleshooting flow-charts calls out “Switch Q1 Fault,” theschematic is used to identify the compo-nents associated with Q1 (ie, capaci-tors, resistors, inductors, etc). Theschematics contain pertinent voltage andwaveform data to aid in fault isolation.

6. Component Location Diagrams. Thecomponent location diagrams for eachunit under test are used for threepurposes:

a. To identify the location of allcomponents in disassembly and reassemblyprocedures.

b. To identify the location of thetest points and pins required in theperformance test and troubleshootingflowcharts to monitor waveforms andvoltages.

c. To identity the location ofevery replaceable component.

3-60. DESCRIPTION OF COMPONENT LOCATIONDIAGRAMS. The component location dia-grams provide physical identification

of all replaceable piece parts in the amplifier-converter.The component location diagrams provide componentlocation information only; for ordering of piece partsrefer to the Repair Parts and Special Tools List. Therea separate diagram for the amplifier-converter and eachcircuit card and the cable assemblies. Each componentlocation illustration is supported by a parts list with twocolumns of data, as follows:

1. ITEM Column. Item numbers areassigned in numerical sequence, startingwith 1, which correspond to the itemnumbers on the component location illus-trations for each component. Numbersare assigned clockwise, starting at thetop of the illustration. For circuitcard assemblies, the actual referencedesignator is used instead of a sequencenumber; the sequence is again clockwise,starting at the top.

2. DESCRIPTION Column. Containsshort name or description of each com-ponent. May also contain referencedesignator number where necessary.

3-36

TM 11-5820-922-40-1

CHAPTER 4

AMPLIFIER-CONVERTER AM-6879/URC

SECTION I

INTRODUCTION

4-1. INTRODUCTION.

4-2. This chapter presents detailedmaintenance data to assist the techni-cian in maintaining the amplifier-converter A1 (fig 4-1). The dataprovided enables fault isolation to aremovable component or component group.Troubleshooting information, repairdata, and alignment procedures areincluded for complete maintenance.

4-3. The amplifier-converter or Maint KitOA-9163/GRC-193A is used as a maintenance testbed. Operating power is supplied to the best bed via afabricated power cable (fig 3-10A) which con-nects +28v to the amplifier-converter.The amplifier-converter can be turned onwith the switch on the fabricated poweron/off switch connector (fig 3-10D).from the amplifier-converter using a fab-ricated card extender cable (fig 3-10B)for component access during test andtroubleshooting. Maintenance proceduresfor the amplifier-converter are pre-sented in each chapter as follows:

1.

2.

3.

4.

5.

6.

4-4.

4-5.

Disassembly and Reassembly

Cleaning and Examination

Performance Test andTroubleshooting

Repair and Replacement

Component Location and Parts List

Maintenance Diagrams (schematic,power distribution, test setup,and performance

TEST EQUIPMENT.

Table 4-1 lists

test flowchart.

the test equipmentrequired to test the amplifier-converter;equivalent test equipment may be used.

4-6. SPECIAL TOOLS AND MATERIALS.

4-7. Table 4-2 lists the special toolsand cables used in the repair and testingof the amplifier-converter.

TABLE 4-1. TEST EQUIPMENT

NOTES: 1. Equivalent test equipment may be used.

2. Use only test equipment that is properly calibrated. Failure to do somay provide erroneous or misleading performance or fault indications.

Name Designation Quantity

Frequency Counter CP-843P/U 1

Audio Oscillator AN/URM-127 1

Power Supply, DC Hewlett-Packard HP-6439B 1

Multimeter Simpson 260-6P 1

4-1

Figure 4-1.

TM 11-5820-922-40-1

4-2

TM 11-5820-922-40-1

TABLE 4-2. SPECIAL TOOLS, MATERIALS, AND FABRICATED TEST CABLES

Note: Referenced figures are contained in chapter 3.

Description Part Number Reference

Power Cable

Audio Connector Adapter

Power On/Off Switch Connector

Kit, Tool, Electronic

Bench Repair Center

Maintenance Kit, Printed Circuit

TTY Jumper

TTY Load Resistor (120Ω, 1 watt)

TK-100/G

Pace PRC-350C

MK-984/A

Figure 3-10A

Figure 3-10C

Figure 3-10D

4-3

TM 11-5820-922-40-1

SECTION II

DISASSEMBLY AND REASSEMBLY

4-8. INTRODUCTION.

4-9. This section contains disassemblyand reassembly procedures for theamplifier-converter. The procedurescover the removing and replacing of thefive circuit card assemblies (A1A1,A1A2, A1A3A1, A1A4A1 and A1A4A2), theribbon cable, and the components of theamplifier-converter.

4-10. DISASSEMBLY (Figure 4-4).

4-11. The disassembly procedures aredescribed in the following paragraphs:

4-12. AMPLIFIER-CONVERTER REAR COVERASSEMBLY A1A3 REMOVAL (Figure 4-4,Sheet 3).

1. Loosen 6 captive screws (28) onrear cover (6).

2. Separate cover (6) from amplifier-converter housing.

3. Remove connector J1 (18) attachedto EMI filter (25) by loosening slottedthumb screws (17).

4. Carefully push connector J1 (18)upward, separating it from connectorassembly P1 (20).

5. Remove J7 (16) by removingretaining nut (1) and lockwasher (2)located on the front of rear cover (6).

6. Remove wire rope assembly (13) byremoving wire rope screw assembly (9).

4-13. EMI FILTER ASSEMBLY A1A3A1REMOVAL (Figure 4-4, Sheet 3).

1. Place rear cover (6) so that theEMI filter (25) faces down, and removeconnector rings (3) from connectors J5(26) and J6 (19). Turn rear cover (6)over for next step.

4-4

2. Remove E9 ground assembly (21)from rear cover (6) by removing thescrew (22), ground lug (23), and flatwasher (24).

3. Grasp EMI filter (25) and removeit from rear cover (6).

4-14. AMPLIFIER-SQUELCH ASSEMBLY A1A2REMOVAL (Figure 4–4, Sheet 1).

1. Remove amplifier-squelch (6) byloosening 4 captive screws (3) andcarefully pull circuit card handle (34),separating card from connector J4.

4-15. TTY-FSK CONVERTER ASSEMBLY A1A1REMOVAL (Figure 4-4, Sheet 1).

1. Remove TTY-FSK converter (40) byloosening the 4 captive screws (38) andcarefully pulling the circuit cardhandle (39), separating card fromconnector J3.

NOTE

The remainder of removalprocedures, paragraphs 4-16thru 4-24, are performed afterremoval of the rear cover,amplifier-squelch, and TTY-FSKconverter assemblies (para4-12, 4-13 and 4-15).

4-16. AUDIO FILTER ASSEMBLY A1A4A1 ANDCONNECTOR ASSEMBLY REMOVAL (Figure 4-4,Sheet 1, and Figure 4-5, Sheet 1).

1.

CAUTION

Use extreme care when removingor replacing ribbon cables.Creasing or severe bending willdamage ribbon cables internally.

Unsolder ribbon cable at E6, E5,E2, E3, E4, E1, E7, and E8 (fig 4-3,sheet 1), and loosen captive screw (7)on back of the audio filter (28), (fig4-4, sheet 1).

TM 11-5820-922-40-1

2. At the audio filter connectors J2(30), J1 (31) on the front of theamplifier-converter, loosen and removethe connector rings (17).

3. From the back of the amplifier-converter (12), carefully pull the audiofilter (28) backwards to remove it.

4-17. RIBBON CABLE REMOVAL (Figure 4-5).

4-19. TTY ON/OFF/SPKR ON S1 AND SQUELCHSWITCH R1/S2 REMOVAL (Figure 4-4,Sheet 2).

1. On front of the amplifier-converter,remove the switch knob (15 or 15A) (fig4-2, sheet 2) by loosening the 2 Allensetscrews (16) (fig 4-4, sheet 2) onthe side of the knob (15 or 15A) (fig4-2, sheet 2).

2. Remove retaining nut (14) andCAUTION washer (13) from the threaded portion of

Use extreme care when removingthe switch shaft (12) (fig 4-2,sheet 2).

or replacing ribbon cables.Creasing or severe bending 3. From the back of the switch,will damage ribbon cables unsolder the ribbon cable (12 places forinternally. S1, 5 places for R1/S2).

1. Unsolder ribbon cable at thefollowing terminal points: E6, E5, E2,E3, E4 E1, E7, E8 (located on the audiofilter); fuseholder XF1 2 places;squelch control R1/S2 5 places; loopcurrent test points TP1 and TP2; loopcurrent adjust R2 3 places; TTY keyE1-E2 and DC loop E3-E4; loop currentselect S3 2 places; E5, E6 and removenut at E7 located above J3. UnsolderEMI filter cable assembly at E8, E9,E10, E11, E12, and E13 located adjacentto J4. Unsolder TTY ON/OFF SPKR ONswitch S1 at 12 places.

2. Remove retaining screws (7) and(2) from connectors J4 and J3. Pull J4and J3 backwards removing them from theamplifier-converter housing.

3. Carefully remove entire ribboncable (11) from the housing.

4-18. SPEAKER ASSEMBLY REMOVAL (Figure4-4, Sheet 1).

1. On the front of amplifier-converter control panel speaker assembly(22), loosen the 4 captive screws (21)on the speaker cover (23).

2. Carefully separate the speakerassembly (22) from the amplifier-converter housing (12) and unsolderspeaker wires (26) from speakerterminals E5 and E6 (25).

4. Carefully remove the ribbon cablefrom the switch and pull the switch back-wards, removing it from the amplifier-converter control panel (4) (fig 4-4,sheet 2).

5. Repeat steps 1 thru 4 for removingsquelch switch (R1/S2) (15A) (fig 4-4,sheet 2).

4-20. METER CONNECTORS TP1 AND TP2REMOVAL (Figure 4-4, Sheet 1).

1. From the back of the amplifier-converter, unsolder TP1 and TP2 from theribbon cable.

2. Carefully separate the unsolderedportion of the ribbon cable from TP1 andTP2.

3. Remove retaining nuts and washersfrom the meter connectors (13 and 14).

4. At the front of theamplifier-converter, grasp the meterconnectors (13 and 14) and slowly pulloutward, separating meter connectors (13and 14) from the housing.

4-21. SELECT SWITCH S3 REMOVAL (Figure4-4, Sheet 2).

1. Remove retaining nut (7) andwasher (6) from the threaded portion ofthe switch S3 (1).

4-5

TM 11-5820-922-40-1

2. From the back of the amplifier-converter, unsolder the ribbon cablefrom the switch terminal points.

3. Carefully separate the ribboncable from the switch.

4. From the back of amplifier-converter, pull the switch S3 (2) slowlyto remove it.

4-22. ADJUST POTENTIOMETER R2 REMOVAL(Figure 4-4, Sheet 2).

1. From the amplifier-convertercontrol panel (4), remove jam nut (8)and retaining nut (9) from the threadedportion of the potentiometer (11).

2. From the back of the amplifier-converter, unsolder R2 (3 places) fromthe ribbon cable.

3. Carefully remove the ribbon cablefrom the potentiometer and pull thepotentiometer backwards to remove itfrom the housing.

4-23. AMPLIFIER-CONVERTER BINDING POSTREMOVAL (Figure 4-4, Sheet 2).

1. From the back of the amplifier-converter, unsolder ribbon cable at E2,E4, E1, E3 and carefully fold backribbon cable.

2. Remove rfi filter (22) and E9ground (26) from the back of the bindingposts by removing nut (25), lockwasher(24), and flat washer (23); also removebushing (21).

3. From the front of amplifier-converter, grasp binding post (17) andslowly pull outward to remove bindingpost from amplifier-converter housing.

4-24. FUSEHOLDER XF1 REMOVAL (Figure4-4, Sheet 2).

1. From the back of amplifier-converter, unsolder fuse terminals (29)at 2 places on the ribbon cable.

2. Carefully fold back ribbon cable.

3. Remove nut (27) and washer (28)from the backside of the fuseholder(29).

4. Grasp fuseholder (30) from thefront of the amplifier-converter controlpanel (4) and pull outward to remove it.

4-25. REASSEMBLY.

4-26. Reassembly procedures for theamplifier-converter are described in thefollowing paragraphs.

NOTE

When replacing the spare fuse-holder located in the rearcover assembly, refer to para-graph 4-11 and figure 4-4,Sheet 2.

4-27. FUSEHOLDER XF1 REPLACEMENT(Figure 4-4, Sheet 2).

1. From the front of the amplifier-converter control panel (4) alignfuseholder (30) into position so thatthe threaded portion is visible from theback of the amplifier-converter.

2. From the back of the amplifier-converter control panel (4), attachwasher (28) and nut (27) to the backsideof the fuseholder (30) and tighten.

3. Carefully fold the ribbon cableinto position and solder fuseholderterminals (29) to the ribbon cable.

4-28. BINDING POST REPLACEMENT (Figure4-2, Sheet 2).

1. From the front of the amplifier-converter, place bushing (19) , preformpacking (20) onto binding post shaft(18) and push binding post (17) intoposition so that the threaded portionis visible from the back of theamplifier-converter.

2. Replace bushing (21) and rfifilter (22) onto binding post shaft(18), and attach washer (23), lockwasher(24), E9 ground (26), and nut (25) andtighten.

4-6

TM 11-5820-922-40-1

3. Carefully fold the ribbon cableinto position and solder rfi filter (22)at E2, E4, E1, and E3.

4-29. ADJUST POTENTIOMETER R2REPLACEMENT (Figure 4-4, Sheet 2).

1. From the back of the amplifier-converter, align the potentiometer R2(11) and push into place, so that thethreaded portion is visible from thefront of the control panel (4).

2. From the front, attach the flatwasher (10), retaining nut (9) and jamnut (8) and tighten.

3. From the back, solder potenti-ometer R2 to the ribbon cable at 3places.

4-30. SELECT SWITCH S3 REPLACEMENT( Figure 4-4, Sheet 2).

1. Place key washerwasher (3) on threadedswitch.

2. From the back of

(2) and flatportion of the

the amplifier-converter, align the switch (1) andpush into place so that the toggle andthreaded portion of the switch arevisible from the front of the amplifier-converter control panel (4).

3. Place key washer (5), flat washer(6), and retaining nut (7) onto threadedportion of switch and tighten.

4. From the back, carefully fold theribbon cable back into position.

5. Solder terminal points at the rearof switch (1) at 2 places to the ribboncable.

4-31. METER CONNECTORS TP1 AND TP2REPLACEMENT (Figure 4-4, Sheet 1).

1. From the front of the amplifier-converter, align meter connectors (13and 14) and push into place.

2. Attach washers and retaining nutsto the threaded portion of the rear ofthe connectors.

3. Carefully fold ribbon cable backinto position and solder to TP1 and TP2.

4-32. TTY ON/OFF/SPKR ON SWITCH S1REPLACEMENT (Figure 4-4, Sheet 2).

1. From the back of the amplifier-converter, align and push switch S1 intoplace so that the threaded portion ofthe switch shaft (12) is visible fromthe front face of the amplifier-convertercontrol panel (4).

2. Replace washer (13) and retainingnut (14) and tighten into position.

3. Align knob (15) with switch shaft(l2), push into place, and tighten 2Allen setscrews (16) on the side of theknob.

4. From the back of the amplifier-converter, carefully place the ribboncable in position , and solder the switch(S1) to the ribbon cable.

4-33. SQUELCH SWITCH R1/S2 REPLACEMENT(Figure 4-4, Sheet 2).

1. From the back of the amplifier-converter, align and push the switchR1/S2 into place so that the threadedportion of the switch shaft (12) isvisible from the front of the amplifier-converter control panel (4).

2. Replace washer (13) and retainingnut (14) and tighten into position.

3. Align knob (15A) with switch shaft(l2), push into place, and tighten 2Allen setscrews (16) on the side of theknob.

4. From the back of the amplifier-converter, solder R1/S2 to the ribboncable at 5 places.

4-7

TM 11-5820-922-40-1

4-34. SPEAKER ASSEMBLY REPLACEMENT(Figure 4-4, Sheet 1).

1. Align the speaker (24) withmounting holes on the front face of theamplifier-converter housing (12) withthe speaker terminals (25) facingupwards.

2. Solder the speaker wires (26) ontospeaker terminals E5 and E6 (25).

3. Align the speaker cover (23) withthe speaker (24) and push them together.

4. Align the speaker assembly (22)with the mounting holes in the Amplifier-converter housing (12), and carefullypush into place and tighten the4 captive screws (21).

4-35. RIBBON CABLE ASSEMBLY REPLACEMENT(Figure 4-5, Sheet 1).

CAUTION

Use extreme care when removingor replacing ribbon cables.Creasing or sharp bending willdamage ribbon cablesinternally.

1. Align the ribbon cable so thatconnectors J4 (6) and J3 (1) are alignedwith internally-threaded mounting stand-offs (10 and 5).

2. Carefully push connectors J4 andJ3 into position and tighten connectorretaining screws (7 and 2).

3. Solder ribbon cable at thefollowing terminals; E6, E5, E2, E3,E4, E1, E7, E8 (located on the audiofilter); fuseholder XF1 2 places;squelch control R1/S2 5 places; loopcurrent test points TP1 and TP2; loopcurrent adjust R2 3 places; TTY KEY E1and E2; DC loop E3 and E4; binding postsE1-E2 and E3-E4; loop current select S32 places; E5; E6; and E7 located aboveJ3; TTY ON/OFF/SPKR ON switch S1 12places. Resolder EMI filter cableassembly at E8, E9, E10, E11, E12,and E13 located between J3 and J4.

4-36. AUDIO FILTER ASSEMBLY A1A4A1 ANDCONNECTOR ASSEMBLY REPLACEMENT(Figure 4-4, Sheet 1).

1. Align audio filter (28) withappropriate holes in amplifier-converterhousing (12).

2. Push audio filter (28) intoposition so that the threaded portion ofthe connectors is visible from the frontof the amplifier-converter housing (12).

3. Attach 2 connector rings (17) toconnectors J2 (30), J1 (31) and tighten.

4. At the back side of the audiofilter (28), tighten captive screw (7).

5. Solder ribbon cable to the audiofilter at the following locations: E6,E5, E2, E3, E4, E1, E7, and E8.

4-37. TTY-FSK CONVERTER ASSEMBLY A1A1REPLACEMENT (Figure 4-4, Sheet 1).

1. Align TTY-FSK converter connectorP1 (35) with J3 (inside the housing(12)) and carefully push into place.

2. Tighten the 4 captive screws (37).

4-38. AMPLIFIER-SQUELCH ASSEMBLY A1A2REPLACEMENT (Figure 4-4, Sheet 1).

1. Align amplifier-squelch connectorP1 (33) with J4 (inside the housing(12)) and carefully push into place.

2. Tighten the 4 captive screws (3).

4-39. EMI FILTER ASSEMBLY A1A3A1REPLACEMENT (Figure 4-4, Sheet 3).

1. Align EMI filter (25) with rearcover (6) and push into position.

2. Align connector rings (3) withconnectors J5 (26), J6 (19) and tighteninto position.

3. Align E9 ground assembly (21) andtighten into place securing screw (22),locking ground lug (23), and flat washer(24).

4-8

TM 11-5820-922-40-1

4-40. AMPLIFIER-CONVERTER REAR COVERASSEMBLY A1A3 REPLACEMENT (Figure 4-4,Sheet 3).

1. Align J7 (16) with appropriatehole in rear cover (6).

2. Push J7 (16) into position andattach lockwasher (2) and retaining nut(1) and tighten.

3. Align connector J1 (18) withcircuit board connector P1 (20), andcarefully push into place and tighten2 slotted thumb screws (17).

4. Align wire rope screw assembly (9)with the mounting stud (15), attach andtighten.

5. Align cover (6) with amplifier-converter housing, fit in place, andtighten 6 captive screws (28).

4-9

TM 11-5820-922-40-1

SECTION III

CLEANING AND EXAMINATION

4-41. INTRODUCTION.

4-42. Cleaning and examination of the amplifier-converter is covered in chapter 3,section II.

4-10

TM 11-5820-922-40-1

SECTION IV


4-43. INTRODUCTION.

4-44. The performance test and trouble-shooting have been combined into a flow-chart approach (fig 4-7) with a separatetest setup diagram (fig 4-6). Thisallows the maintenance technician tocheck the overall performance of theamplifier-converter for normal indica-tions, and to branch off for trouble-shooting if the indications are abnormal.The troubleshooting flowchart is used to

isolate to a probable fault and shouldbe used in conjunction with the func-tional block diagrams (chapter 2) andschematics (fig 4-2, 4–3). Once a faulthas been isolated and the equipmentrepaired, repeat the performance test.Do not skip blocks in the performancetest, because succeeding blocks may bepredicated on certain faults having beeneliminated. See figures 4-4 thru 4-7for further explanation of testing andtroubleshooting.

4-11

TM 11-5820-922-40-1

REPAIR

4-45. INTRODUCTION.

SECTION V

AND REPLACEMENT

4-46. Repair and replacement procedures for the circuit cards are provided inchapter 3. Depot rebuild standards for the amplifier-converter housing and cover,and the mounting tray are covered in RS-07749A/07743A-50/5.

4-12

TM 11-5820-922-40-1

SECTION VI

COMPONENT LOCATION AND PARTS LIST

4-47. INTRODUCTION.

4-48. This section contains the component location diagram and repair parts list(fig 4-4 and 4-5) which support the disassembly and reassembly procedures ofsection II.

4-13/(4-14 blank)

T M 1 1 - 5 8 2 0 - 9 2 2 - 4 0 - 1

Figure 4-2. Amplifier-Converter A1 Schematic

4 -15 / (4 -16 b lank)

T M 1 1 - 5 8 2 0 - 9 2 2 - 4 0 - 1

Figure 4-3. Amplifier-Converter A1 Power Distribution

4 - 1 7 / ( 4 - 1 8 b l a n k )

Figure 4-4

Figure 4-4.

T M 1 1 - 5 8 2 0 - 9 2 2 - 4 0 - 1

4-19 / (4 -20 b lank)

T M 1 1 - 5 8 2 0 - 9 2 2 - 4 0 - 1

Figure 4 -4 . Ampl i f ier -Converter Component Locat ion

(Rear Cover Assembly A1A3, Circuit Cards, Switches and Fuse)

(Sheet 2 of 3)

4 - 2 1 / ( 4 - 2 2 b l a n k )

T M 1 1 - 5 8 2 0 - 9 2 2 - 4 0 - 1

Figure 4-4. Amplifier-Converter Component Location(Rear Cover Assembly A1A3, Circuit Cards, Switches and Fuse)

(Sheet 3 o f 3 )4 -23 / (4 -24 b lank)

T M 1 1 - 5 8 2 0 - 9 2 2 - 4 0 - 1

Figure 4-5. Amplifier-Converter Component Location(Ribbon Cable and Connectors)

(Sheet 1 o f 2 )4 -25 / (4 -26 b lank)

T M 1 1 - 5 8 2 0 - 9 2 2 - 4 0 - 1

Figure 4-5. Amplifier-Converter Component Location(Ribbon Cable and Connectors)

(Sheet 2 o f 2 )4 -27 / (4 -28 b lank)

T M 1 1 - 5 8 2 0 - 9 2 2 - 4 0 - 1

Figure 4–6. Amplifier-Converter A1Test Setup

4-29/(4-30 blank)

T M 1 1 - 5 8 2 0 - 9 2 2 - 4 0 - 1

Figure 4-7. Amplifier-Converter A1

Performance Test

4 - 3 1 / ( 4 - 3 2 b l a n k )

TM 11-5820-922-40-1

APPENDIX A

REFERENCES

AR 55-38

AR 735-11-2

AR 755-2

DA Pam 310-1

DA Pam 738-750

TM 11-5820-919-12

TM 11-5820-919-24P

TM 11-5820-919-40-1

TM 11-5820-919-40-2

TM 11-5820-922-12

TM 11-5820-922-40-1

TM 11-5820-922-40-2

TM 11-5820-924-12

TM 11-5820-924-24P

TM 740-90-1

TM 750-244-2

Reporting of Transportation Discrepancies in Shipments

Reporting of Item and Packaging Discrepancies

Disposal of Excess, Surplus, Foreign Excess, Captured, and Unwanted Material

Consolidated Index of Army Publications and Blank Forms

The Army Maintenance Management System (TAMMS)

Operator’s and Organizational Maintenance Manual Radio Set AN/PRC-104A

Organizational, Direct Support and General Support Maintenance Repair Partsand Special Tools List for Radio Set AN/PRC-104A

General Support Maintenance Manual Radio Set AN/PRC-104A

General Support Maintenance Manual Radio Set AN/PRC-104A

Operator’s and Organizational Maintenance Manual Amplifier-ConverterAM-6879/URC

General Support Maintenance Manual Amplifier-Converter AM-6879/URC

General Support Maintenance Manual Amplifier-Converter AM-6879/URC

Operator’s and Organizational Maintenance Manual Radio Sets AN/GRC-193A

Organizational, Direct Support and General Support Maintenance Repair Partsand Special Tools List for AN/GRC-193A

Administrative Storage of Equipment

Procedures for Destruction of Electronic Materiel to Prevent Enemy Use (ElectronicsCommand)

A-1/(A-2 blank)

TM 11-5820-922-40-1

ALPHABETICAL INDEX

Subject

A

Adjust Potentiometer R2 Removal . . . . . . . . . . . . . . . .Adjust Potentiometer R2 Replacement . . . . . . . . . . . . . .Amplifier-Converter

Amplifier-Squelch . . . . . . . . . . . . . . . . . . . . .

Audio Filter. . . . . . . . . . . . . . . . . . . . . . . .

Cleaning and Examination . . . . . . . . . . . . . . . . . .Component Location. . . . . . . . . . . . . . . . . . . . .Detailed Functional Description . . . . . . . . . . . . . .EMI Filter. . . . . . . . . . . . . . . . . . . . . . . . .

Functional Description . . . . . . . . . . . . . . . . . . .Performance Test and Troubleshooting . . . . . . . . . . . .Rear Cover Assembly A1A3 Removal . . . . . . . . . . . . . .Rear Cover Assembly A1A3 Replacement . . . . . . . . . . . .Repair. . . . . . . . . . . . . . . . . . . . . . . . . . .TTY-FSK Converter . . . . . . . . . . . . . . . . . . . . .

Amplifier-SquelchDetailed Functional Description . . . . . . . . . . . . . .Functional Description . . . . . . . . . . . . . . . . . . .Receive Operation . . . . . . . . . . . . . . . . . . . . .Removal, A1A2 Assembly . . . . . . . . . . . . . . . . . . .Replacement, A1A2 Assembly . . . . . . . . . . . . . . . . .Transmit Operation. . . . . . . . . . . . . . . . . . . . .

Audio FilterDetailed Functional Description . . . . . . . . . . . . . .Functional Description . . . . . . . . . . . . . . . . . . .Removal, A1A4A1 Assembly and Converter Assembly . . . . . .Replacement, A1A4A1 Assembly and Converter Assembly . . . .

B

Binding Post Removal. . . . . . . . . . . . . . . . . . . . . .Binding Post Replacement . . . . . . . . . . . . . . . . . . . .Bonded Parts, Removal . . . . . . . . . . . . . . . . . . . . .

C

Circuit CardBase Material Standards . . . . . . . . . . . . . . . . . .Etch Standards. . . . . . . . . . . . . . . . . . . . . . .Repair Procedure. . . . . . . . . . . . . . . . . . . . . .

ParagraphFigure,Table

Number

4-224-29

2-5,2-15,F2-4,2-4,2-14,F2-34-424-482-112-3,2-13,F2-22-1, F2-14-444-124-174-462-8,2-27,F2-5

2-15,F2-42-52-64-144-382-7

2-14,F2-32-44-164-36

4-234-283-25

3-143-153-17

Index-1

TM 11-5820-922-40-1

ALPHABETICAL INDEX (cont)


NumberSubject

C

.

l

.

l

.

.l

.

.

.

(cont)

3-19,T3-1,T3-23-163-42

Repair Tools and Materials

Storage and HandlingCleaning . . . . . . . .Cleaning and Examination

Amplifier-ConverterEMI Filter . . . . .External . . . . . .Internal . . . . . .

Cold Solder Joints . . .

4-427-73-433-453-12,F3-4

ListComponent Location and PartsAmplifier-Converter . . 4-48

3-313-323-46

. . .Component Replacement in Eyelets .Component Replacement in Plated-Through HolesCorrosion Control. . . . . . . . . . . . .

DC Loop . . . . . . . . . . . . . . . . . . .Disassembly and Reassembly

Amplifier-Converter . . . . . . . . . . .

D

2-31

4-10,4-25,F4-4

E

EMI FilterDetailed Functional Description .Functional Description . . . . . .Removal, A1A3A1 Filter Assembly .

2-13,F2-22-34-134-391-11,T1-23-203-473-10,F3-33-43

Replacement, A1A3A1 Filter AssemblyEquipment Supplied . . . . .Etch Repair . . . . . . . .Examination . . . . . . . .Excessive Solder . . . . . .External Cleaning . . . . .

F

Fabrication of Test Cables .Flowcharts, Use of . . . . .Fuse Holder XF1 Removal . .Fuse Holder XF1 Replacement

3-52,F3-103-58,F3-134-244-27

I

3-113-45

Insufficient Solder . . . .Internal Cleaning . . . . .

Index-2

TM 11-5820-922-40-1


Subject

L

Lifted Pad Replacement . . . . . . . . . . . . . . . . . . . . .List of Publications . . . . . . . . . . . . . . . . . . . . . .

M

Meter Connections TP1 and TP2 Removal . . . . . . . . . . . . .Meter Connections TP1 and TP2 Replacement . . . . . . . . . . .Modification of Gold Plated Printed Wiring Circuit Card . . . .

P

Pad Area. . . . . . . . . . . . . . . . . . . . . . . . . . . .Performance Test and Troubleshooting

Amplifier-Converter . . . . . . . . . . . . . . . . . . . .Performance Test. . . . . . . . . . . . . . . . . . . . . .Reference Data. . . . . . . . . . . . . . . . . . . . . . .

Preferred Solder Connection . . . . . . . . . . . . . . . . . .Publications, List of . . . . . . . . . . . . . . . . . . . . .

R

Radio Frequency Interference Filter . . . . . . . . . . . . . .Reassembly, Amplifier-Converter . . . . . . . . . . . . . . . .Receive Operation, Amplifier-Squelch . . . . . . . . . . . . . .Receive Operation, TTY-FSK Converter . . . . . . . . . . . . . .Reference Data. . . . . . . . . . . . . . . . . . . . . . . . .Removal

Adjust Potentiometer R2 . . . . . . . . . . . . . . . . . .Amplifier-Converter Binding Post . . . . . . . . . . . . . .Amplifier-Converter Rear Cover Assembly A1A3 . . . . . . . .Amplifier-Squelch Assembly A1A2 . . . . . . . . . . . . . .Audio Filter Assembly A1A4A1 and Converter Assembly . . . .Bonded Parts. . . . . . . . . . . . . . . . . . . . . . . .EMI Filter Assembly A1A3A1 . . . . . . . . . . . . . . . . .Fuse Holder XF1 . . . . . . . . . . . . . . . . . . . . . .Meter Connections TP1 and TP2 . . . . . . . . . . . . . . .Ribbon Cable. . . . . . . . . . . . . . . . . . . . . . . .Select Switch S3. . . . . . . . . . . . . . . . . . . . . .Soldered Components having Axial Leads . . . . . . . . . . .Soldered Components having Radial Leads . . . . . . . . . .Speaker Assembly. . . . . . . . . . . . . . . . . . . . . .Transistors . . . . . . . . . . . . . . . . . . . . . . . .TTY-FSK Converter Assembly A1A1 . . . . . . . . . . . . . .TTY ON/OFF/SPKR ON and Squelch Switch R1/R2 . . . . . . . .


Number

3-241-15,T1-5

4-204-313-35

3-9

4-443-513-573-13,F3-51-15,T1-5

2-32,F2-64-252-62-9, 2-281-8

4-224-234-124-144-163-254-134-244-204-174-213-273-284-183-294-154-19

Index-3

TM 11-5820-922-40-1


Subject

R (cont)


Number

Repair ofAmplifier-Converter . . . . . . . . . . . . . . . . . . . .Broken Gold-Plated Copper Etch . . . . . . . . . . . . . . .Broken Thermal Mounting Plate Power or Ground Tabs . . . . .Concealed Short Circuit in Printed Wiring Assemblies . . . .Damaged Fiber Glass Epoxy Parts . . . . . . . . . . . . . .Defective Plated-Through Holes . . . . . . . . . . . . . . .Polyurethane Conformal Coating . . . . . . . . . . . . . . .Raised or Unbended Gold-Plated Copper Etch . . . . . . . . .Scratched, Gouged, Voided or Pinholed Etch . . . . . . . . .Thermal Mounting Plate on High-Density Printed Wiring Boards

ReplacementAdjust Potentiometer R2 . . . . . . . . . . . . . . . . . .Amplifier-converter Rear Cover Assembly A1A3 . . . . . . . .Amplifier-Squelch Assembly A1A2 . . . . . . . . . . . . . .Audio Filter Assembly A1A4A1 and Converter Assembly . . . .Binding Post. . . . . . . . . . . . . . . . . . . . . . . .EMI Filter Assembly A1A3A1 . . . . . . . . . . . . . . . . .Fuse Holder XF1 . . . . . . . . . . . . . . . . . . . . . .Lifted Pad. . . . . . . . . . . . . . . . . . . . . . . . .Meter Connection TP1 and TP2 . . . . . . . . . . . . . . . .Ribbon Cable Assembly . . . . . . . . . . . . . . . . . . .Select Switch S3. . . . . . . . . . . . . . . . . . . . . .Soldered Components . . . . . . . . . . . . . . . . . . . .Speaker . . . . . . . . . . . . . . . . . . . . . . . . . .Squelch Switch R1 and R2 . . . . . . . . . . . . . . . . . .TTY-FSK Converter Assembly A1A1 . . . . . . . . . . . . . .TTY ON/OFF/SPKR ON Switch S1 . . . . . . . . . . . . . . . .

Ribbon Cable Removal . . . . . . . . . . . . . . . . . . . . . .Ribbon Cable Replacement . . . . . . . . . . . . . . . . . . . .

S

Scope of the Technical Manual . . . . . . . . . . . . . . . . .Select Switch S3 Removal . . . . . . . . . . . . . . . . . . . .Select Switch S3 Replacement . . . . . . . . . . . . . . . . . .Soldered Components

Having Axial Leads Removal . . . . . . . . . . . . . . . . .Having Radial Leads Removal . . . . . . . . . . . . . . . .Replacement

SolderingCold Joints . . . . . . . . . . . . . . . . . . . . . . . .Excessive . . . . . . . . . . . . . . . . . . . . . . . . .Insufficient. . . . . . . . . . . . . . . . . . . . . . . .Pinholes. . . . . . . . . . . . . . . . . . . . . . . . . .

4-463-223-363-373-343-393-333-233-213-38

4-294-404-384-364-284-394-273-244-314-354-303-304-344-334-374-324-174-35

1-14-214-30

3-273-28

3-12, F3-43-10, F3-33-113-8, F3-2

Index-4

TM 11-5820-922-40-1


Subject

S (cont)

Preferred Connection . . . . . . . . . . . . . . . . . . . .Standards for Circuit Cards . . . . . . . . . . . . . . . .Voids . . . . . . . . . . . . . . . . . . . . . . . . . . .

Speaker Assembly Removal . . . . . . . . . . . . . . . . . . . .Speaker Assembly Replacement . . . . . . . . . . . . . . . . . .Special Maintenance Facility Requirements . . . . . . . . . . .Special Tools and Materials . . . . . . . . . . . . . . . . . .

Squelch On/Off. . . . . . . . . . . . . . . . . . . . . . . . .Squelch Switch R1 and R2 Replacement . . . . . . . . . . . . . .Standards . . . . . . . . . . . . . . . . . . . . . . . . . . .

Circuit Card Base Material . . . . . . . . . . . . . . . . .Circuit Card Etch . . . . . . . . . . . . . . . . . . . . .Soldering Circuit Cards . . . . . . . . . . . . . . . . . .

Storage and Handling of Circuit Cards . . . . . . . . . . . . .Support Equipment . . . . . . . . . . . . . . . . . . . . . . .

T

Technical Characteristics . . . . . . . . . . . . . . . . . . .Technical Manual, Scope of . . . . . . . . . . . . . . . . . . .Test Equipment. . . . . . . . . . . . . . . . . . . . . . . . .

Transistors, Removal . . . . . . . . . . . . . . . . . . . . . .Transmit Operation, Amplifier-Squelch . . . . . . . . . . . . .Transmit Operation, TTY-FSK Converter . . . . . . . . . . . . .Troubleshooting Inspection . . . . . . . . . . . . . . . . . . .TTY-FSK Converter

Detailed Functional Description . . . . . . . . . . . . . .Functional Description . . . . . . . . . . . . . . . . . . .Receive Operation . . . . . . . . . . . . . . . . . . . . .Removal, A1A1 Assembly . . . . . . . . . . . . . . . . . . .Replacement, A1A1 Assembly . . . . . . . . . . . . . . . . .Transmit Operation. . . . . . . . . . . . . . . . . . . . .

TTY ON/OFF/SPKR ON and Squelch Switch R1/S2 Removal . . . . . .TTY ON/OFF/SPKR ON and Squelch Switch R1/S2 Replacement . . . .

U

Use of Flowchart. . . . . . . . . . . . . . . . . . . . . . . .

V


Number

3-13, F3-53-63-7, F3-14-184-341-14T1-4,4-6,T4-22-224-333-53-143-153-63-161-12, T1-3

1-10, T1-11-14-4, T4-1T1 -33-292-72-10, 2-293-50

2-27, F2-52-82-94-154-372-104-194-32

3-56, F3-13

Visual Inspection . . . . . . . . . . . . . . . . . . . . . . . 3-49

Index 5/(Index 6 blank)

By Order of the Secretary of the Army:

Official:

MILDRED E. HEDBERGBrigadier General, United States Army

The Adjutant General

Distribution:

To be distributed in accordance with special list.

JOHN A. WICKHAM JR.General, United States Army

Chief of Staff

*U.S. GOVERNMENT PRINTING OFFICE: 1985-611-098:20267

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