Date post: | 08-Feb-2016 |
Category: |
Documents |
Upload: | noe-vidal-aspeitia |
View: | 39 times |
Download: | 0 times |
SAFETY INFORMATION CAUTIONSafety information is contained in the appropriate Service Data. All product safetyrequirements must be complied with prior to returning the instrument to theconsumer. Servicers who defeat safety features or fail to perform safety checks maybe liable for any resulting damages and may expose themselves and others topossible injury.
All integrated circuits, all surface mounted devices, andmany other semiconductors are electrostatically sensitiveand therefore require special handling techniques.
First Edition - First PrintingCopyright 2005 Thomson, Inc.Trademark(s)® Registered Marca(s) Registrada(s)RCA and the RCA logos are trademarks ofTHOMSON S.A. used under license toTTE CorporationPrinted in U.S.A.
Prepared byThomson, Inc for TTE Technology, Inc.Technical Training Department, INH905PO Box 1976Indianapolis, Indiana 46206 U.S.A.
FOREWORDThis troubleshooting guide is designed to aid the service technician in troubleshootingthe ITC008 chassis. It will provide general information on circuit operation,troubleshooting procedures, and some common failures reported to Thomson’sTech-Line.
The troubleshooting procedures may include circuit verification procedures used toeliminate a circuit area from the troubleshooting steps. When using the circuitverification procedures, care must be exercised to prevent further damage to the set.
Reference material referred to by this manual includes:
• ESI service data
• Training Manual
• Parts Finder (for Part Numbers)
Page 4
ContentsFOREWORD .................................................................................... 3SAFETY INFORMATION CAUTION ................................................. 3Troubleshooting Fundamentals ..................................................... 5ITC008 Shutdown............................................................................ 7 XRP EHT Shutdown ................................................................... 8 Over Voltage / Over Current Shutdown (Pincushion).............. 8 +12Vr Shutdown......................................................................... 8 I2C Bus Communication Shutdown ......................................... 8 Shutdown Troubleshooting Flow Chart ................................... 9ITC008 Power Supply Troubleshooting....................................... 10 Dual Voltage Regulator IP030 ................................................. 12IT008 Deflection Troubleshooting ............................................... 13 Vertical Deflection Troubleshooting ....................................... 14 Horizontal Defleciton Troubleshooting .................................. 16 Alternate Vertical Troubleshooting Information .................... 18ITC008 Pincushion Shutdown Troubleshooting ......................... 19
Page 5
This troubleshooting guide covers several circuit areas. These areas are related todead set or shutdown type symptoms only.
Circuit areas are:
• Power Supply
• Deflection (Horizontal and Vertical)
• Pincushion Shutdown
• Shutdowns
Troubleshooting FundamentalsOne definition of troubleshooting is the diagnosis and repair of malfunctions inelectronic equipment using “Logical Analysis” and “Systematic Checks”. The keyphrases of this definition are Logical Analysis and Systematic Checks. Without theapplication of these two principles, troubleshooting complex electronic circuitry is, atbest, a hit or miss proposition. It’s also known in some circles as “Shot-Gunning”.
It’s important to remember that troubleshooting is something of an art form and is asmuch a mental process as it is checking waveforms and voltages. In order toeffectively troubleshoot electronic equipment there are several skills the technicianmust have.
The technician must have:
• A solid understanding of basic electronics. He or she must understand howa transistor, resistor, capacitor, coil, diode, etc. work. They must alsounderstand AC and DC circuits. Even with the best test equipment, withoutthis basic understanding of electronics, the technician is only guessing as tothe cause of a malfunction.
• A basic knowledge and understanding of how all the parts of theinstrument function together and how they affect each other. Thisoverview of system operation is necessary in order to understand how theindividual circuits can affect the overall operation of the equipment. Thisis necessary in order to be able to associate a malfunction or symptomwith a circuit. In other words, could the suspected circuit cause thespecific type of symptom seen?
Page 6
When discussing troubleshooting techniques or principles there are a couple ofthings that should be kept in mind. First, no one can teach a technician the best wayto troubleshoot. Troubleshooting is a skill that’s very individualistic. This means thateach and every technician will troubleshoot the same problem or malfunctiondifferently. That doesn’t mean one method is right and the other is wrong, just thatthere are many different ways of solving a problem and that’s what troubleshootingis all about….Problem Solving. However, there are some basic steps and guidelinesthat can help a technician get started. A skilled technician will develop his or her ownstyle with time and experience.
In most cases troubleshooting can be divided to three basic levels or steps:
1. SECTIONALIZE
2. LOCALIZE
3. ISOLATE
SECTIONALIZE; determine which major functional group or section of the instrumentcontains the fault. Generally, most problems can be sectionalized by carefullyanalyzing the symptom.
LOCALIZE; determine which major circuit within a section can or cannot cause theexhibited symptom. This usually requires checking major or key test points.
ISOLATION; find and repair the stage and/or component that has failed. This steprequires detailed measurement and monitoring of signals and voltages within thesuspected circuit area.
To quickly and efficiently diagnose a malfunction, the technician should follow a setsequence of steps each time he services a piece of equipment. There are five (5)basic steps in troubleshooting or symptom analysis.
1. Physical Inspection
2. Operational Check
3. Sectionalize
4. Localize
5. Isolate
Page 7
Following these five simple steps and having a basic understanding of electronicsalong with how the equipment works will organize the technician’s troubleshootinginto a logical pattern or sequence and increase their effectiveness as a troubleshooter.Remember, these are only principles and can be interpreted in many different ways.Also, troubleshooting is a very unique skill and is learned by doing. All theseprinciples and concepts can be applied to servicing virtually any type of product orequipment. The five steps of troubleshooting may seem obvious to some or complexto others but with time and experience they will become second nature
ITC008 ShutdownShutdown consists of:
• An XRP circuit that monitors the heater pulse from pin 12 of LL05.
• Over voltage and over current shutdown for pincushion
• +12Vr shutdown
• I2C Bus Communication shutdown
Determining which shutdown circuit to troubleshoot is the key. There is no quick wayand from past experience, one just needs to start the process of elimination andeliminate them one at a time.
Each shutdown has it’s own “trigger”. This “trigger” is what causes the shutdown tooccur. More then one “trigger” my feed into a single shutdown circuit. These typesof shutdowns seem to be the most difficult to troubleshoot. For example, in theITC008 pincushion shutdown over current and over voltage are on the same linefeeding the shutdown of horizontal drive. In this same shutdown circuit, feedbackfrom the IHVT (LL005) is used to kill drive signal while energy is still being transferredfrom LL005. In this shutdown there are three signals that can kill horizontal drive andshutdown the set. Knowing how to disable each will aid in troubleshooting what“trigger” is causing the shutdown.
This section will provide troubleshooting tips on how each shutdown “trigger” can beisolated in a safe manner. In some cases there is no way to isolate the triggertherefore, some understanding of the shutdown will help logic out the “trigger”. Othertimes it is trial and error.
Page 8
XRP EHT Shutdown
Use extreme caution when doing this procedure!!
Start by disconnecting the CRT anode lead and CRT socket. Then locate JL905 atgrid location 8,UU on the main CBA. Unsolder one end. This disables both the EHTand excessive current shutdown for high voltage. Use caution with XRP EHTshutdown disabled and keep on-times to a minimum.
Over Voltage / Over Current Shutdown (Pincushion)
This is by far the easiest to disable. The feed back information that causes shutdowncomes through connector BF001. By unplugging this connector the shutdown isdisabled.
+12Vr Shutdown
This is not a typical shutdown circuit but more a lack of run voltage issue. The +12Vris used as the run voltage for Horizontal driver amp TL033. If this voltage is missingTL033 will start but never run. Supplying the +12Vr from an external DC sourceverifies the +12Vr as the problem. This voltage should be supplied to the Cathodeof DL012 and referenced to cold ground while the set is pulsing or trying to start.
I2C Bus Communication ShutdownWith this shutdown it is a trial and error situation. Error codes are logged forcommunication shutdown but can only be read if the set is operational. Knowing thatthe Tuner, MAV CBA, and Alert Guard CBA are the only communication problemsreported it is safe to use the process of elimination for this shutdown.
The Alert Guard CBA is the only one that is of Plug and Play nature. Both the Tunerand MAV CBA will cause shutdown if connected or not. Therefore; trying the Tunerand the MAV are by trial and error.
Page 9
Shutdown Troubleshooting Flow Chart
The above flow chart is used to troubleshoot a dead set or shutdown condition. Thischart and the troubleshooting sections found in this guide cover those scenariosfound during calls to Tech-line. They do not cover all possible scenarios, only themost common or unique ones.
Apply AC power andpress the power switch.
Does the set Pulse 3 timesand quit or Cycle every 5 sec.
continuously
Pulse at 5 SecIntervals
Cycles 3 Times
Disconnect the AlertGuard Module.
Try to turn on theset. Does the set
start?
Suspect the AlertGuard Module
Disconnect thePincushion Connector
BF001
Try to turn on theset. Does the set
start?
TroubleshootHorizontal Deflection
Troubleshoot PowerSupply
Troubleshoot SystemControl
Communication I2CBus
Tuner and MAV?
Suspect thePincushion Module
Try to turn on theset. Dead or
Pulsing?Dead
Pulsing
YES
NO
YES
NO
Does the set haveAlert Guard? NO
YES
Page 10
ITC008 Power Supply Troubleshooting(Dead Set, Power supply voltages missing or incorrect)
NOTE: DP027 will short whenever feedback is lost or an excessive load on thesecondary of LP003 is present. This will shut down the power supply. IF DP027 isshorted, check FZP61. If FZP61 is open, check the +13.1V for excessive load andcheck the feedback circuit (IP001, TP022, and IP050) for proper operation.
1. Check RAW B+, if not OK check the full wave bridge rectifier DP002/003/004/005and it’s associated components.
2. If RAW B+ OK, check the current sensing resistor RP020. If open, this wouldindicate there has been a severe over current condition between the drain andsource of TP020. Check and replace all defective active components on theprimary side of LP003. Check for excessive loads off secondary of LL03 beforereapplying AC power.
3. Check for DC voltage and waveform on the gate of TP020. A waveform, like theone on page 11, indicates the oscillator is running. If there is no waveformunsolder the drain of TP020 and check for 7.8Vdc on the gate. 7.8Vdc on the gateof TP020 indicates start-up circuit is working go to step 5. If a waveform is presenton the Gate of TP020, the primary switching of the supply is working.
3
2
9
5
RAW B+
1
23
41
2
3
+13.1V
Ω0.27
GD
S
1
+6.3Vs
+21.5V
+126V
+19.5V
Pwr GoodTP193,192
PG1
11
10
12
13
14
15
1618
IP001
DP030RP155
IP050CP040
RP041RP026
RP040
DP040
RP030
RP006
RP007
DP005
DP002
DP004
DP003
FP001
CP008
TP020
DP033
RP021
RP033
RP031
RP029
RP023 RP027
TP025
RP132
TP023
TP022
RP028
RP125DP023
RP020
DP025,026
LP003 DP080
CP080FZP603.15A
FZP93500mA
FZP613.15A
RP066
DP093
CP094
CP064DP063
DP097
RP056
RP054 RP158
Slow StartRP037,038
DP037CP037,038
CP039
CP022
TP052
DP057
RP057
RP151
BurstMode
IV001 pin 63
CP062DP202
CP206
DP061
CP024,025DP027
RP052
BeamCurrentSense
8.2V
27V
15V
9.1V
27V
Page 11
Start-up Circuit Test:
Working unit voltages with the Drain of TP020 open: (HOT GND Reference)
• Gate = 7.8V
• Startup ckt = 8.9V (Measured on TP025 (E))
• TP025 C = 8.0V, E = 8.9V, B = 8.3V
• Junction of RP006 and 007 = 32.4V
4. If DC on gate of TP020 is wrong, check TP025, DP027, DP023, RP006, andRP007 and replace if suspect. Hint: 27V on the emitter of TP025 indicates thatthe base circuit of TP025 is open. Check DP023, RP125, RP132, or open circuitto pin 3 of LP003. If there is 0V on the emitter of TP025 and DP027 is shorted,check the regulation feedback circuit associated with IP001 and IP050.
5. If no waveform on gate of TP020 (DC OK), check TP022, TP023 and theirassociated components. Replace all transistors if one has failed or is suspect.If TP020 has failed more than likely the other transistors have been stressed andthe circuit will self-destruct again when plugged into 120 AC.
6. If TP020 checks OK (with primary circuit pulsing), check IP050 (ReferenceRegulator) and IP001 (Opto Coupler) and their associated components. Alsocheck for excessive loads of the secondary of LP003.
Gate of TP020 Waveform Stby Mode
DeviceResistance
to Cold GNDDP080 45.7KDP061 1.4MDP093 5KDP063 7K
Resistance Chart for Power Supply
Page 12
Dual Voltage Regulator IP030
There are two output voltages from IP030 but only one is switched. Pin 4 controlsthe output on pin 8 (7.9V). When pin 4 goes high, there should be 7.9V on pin 8. Thisis easy to check by simply removing (unsoldering) pin 4 and checking the output. Ifvoltage is present on pins 1 and 2 then pin 8 should be 7.9V if IP030 is workingcorrectly.
The other output on pin 9 is 3.3V. This voltage is used for System Control standbyB+ and Pin 6 of IP030 is the reset voltage for IV001 (SysCon). When power is firstapplied, IV001 turns on the dual regulator (IP030) for a short period of time. Duringthis time Degauss is energized and pin 8 of IP030 is switched on supplying the 7.9V.No relay click could indicate IP030 3.3V problem.
IP030 Troubleshooting
1. Check for 13.1V on pin 1 and 2 of IP030. If the voltage is correct go to step2. If missing or not correct troubleshoot standby power supply.
2. Unsolder pin 4 of IP030 and check for 7.9V on pin 8. If the voltage is present,go to step 3. If the voltage is low or missing suspect IP030.
3. Reconnect pin 4 and check for 3.3V on pins 6 and 9. If present, go to step4. If the voltage is low or missing suspect IP030.
4
IP030
DualReg.
8
9
6
Reset
+7.9Vs
+3.3Vs
12 3
IP311 2
+5Vs
1
IV001
LL05
33Horiz Out Horiz
Drive/Out
Pwr ON
14
+181Vr
+33Vr
+12Vr
-12Vr
DH0133V
63
Power SupplyControl
IP01,IP50
+13.1Vs
Burst
Hi = Burst & DAM ModeLo = Energy Mode
TP52
RP57
DP57
RP153
RP151
9.1V
DP36CP66
RP166
FZP66
+VCC
+7.9Vs
CRT
Vertical
Tuner
60
5456
TR02 ResetSwitch
Page 13
4. With pin 4 of IP030 connected, monitor pin 8 and press the power switch. If7.8V momintarly comes up, system control and regulator are workingcorrectly, suspect a Horizontal startup problem. If there is no change on pin8 troubleshoot system control.
ITC008 Deflection Troubleshooting
In order to troubleshoot deflection we must first understand where the signals aregenerated. In the ITC008, IV001 (TV Processor) is used to generate both the Verticaland Horizontal drive signals. The generation of these drive signals depends onseveral external circuits and proper operation of IV001.
First, being system control, IV001needs to have VCC (Stby), GND, OSC, andRESET to function. Next, some sort of user interface (Remote or FPA) to tell IV001what to do. IV001 also needs a set of instructions to perform the expected command.This instruction is in the form of “DATA” found in the EEPROM (IR001). The “DATA”is used to set up registers in IV001. These registers include Horizontal timing,Vertical timing, and shutdown settings. Transfer of "DATA" happens each time theset is turned on. Failure to properly transfer the "DATA" will result in a dead setcondition.
This troubleshooting section assumes certain sections of IV001 are working correctly.These sections are System Control and Signal Processing.
IV001TV Micro
Clk/Data2,3
5,6
IR001
EEPROM
6 7 64KB/LED IR
BR001to Front Panel
8 +5Vs
14 +7.9VsD
61 +3.3V VDD
RESET60
+3.3V VCCD Core
54,56
1 PWR ON
39
12,18,30,41,57
GND
58,59
QV00158
59
57 OSC GND
IN
OUT
33
36
Horiz Out
XRP EHT
PLL Ckts15, 19, 16, 17
21, 22
VDrive
Page 14
Vertical Deflection Troubleshooting(No Vertical Deflection)
Setup: Remove CRT Socket, apply AC power and turn on set. When troubleshootinga Vertical deflection problem where the set is operated without deflection it iscustomary to remove the CRT socket(s) to prevent the CRT from being burnt.
1. Check for –12V on pin 4 of IF001 referenced to cold ground. If missing suspectDL010 and RL010 or a problem with the –12V supply. If correct proceed tostep 2.
2. Check for proper waveform on pins 1 and 7 of IF001. These waveforms aregenerated by IV001. If not correct, troubleshoot IV001 vertical section orsuspect EEPROM alignment data corruption. If waveforms are present,check for 48V P-P on pin 5 of IF001. If present IF001 is working and problemis in the yoke circuit. If not go to the next step.
3. Compare the voltage found on pin 2 with that found on pin 6 of IF001. Thesetwo voltages should be about .3V different. If they are equal, DF010 shouldbe replaced.
4. Check for –10.3V on pin 3 of IF001. This is the boost circuit for IF001. Whenthis voltage is missing suspect IF001, CF010 and DF010. If correct IF001 isworking and problem is in the yoke circuit.
Hint: If set is shutting down and removing DL062 allows the set to operate with outvertical deflection, suspect IF001, DF010, and CF010. These are the most commonfailures of the Vertical circuit causing the set to shutdown. Also check the +12Vrcircuit (RL012 and DL012) off pin 6 of IHVT (LL005).
NOTE: Settings in the EEPROM (Vertical) can also cause shutdown. Misalignmentof Vertical Slope (parameter #06) and Vertical Amplitude (parameter #08) can causethe protection signal from the E/W module to activate and shutdown the instrument.
To correct for this problem, temporarily disconnect BL101on the E/W module torestart the instrument and reset both parameters.
Page 15
IV001
21
22
14 PWRAMP
IF001Vertical Output
51
7
4
2 6 3
RV06 RF02
DF02
RV05
DF03
RF03
RF04
RF06
CF05 DF10 CF10
DF101
DF102
RF101
CF101
DF0156V
RF08 RF09
CF09
RF07
CF08
BF002
RF102Beam Current Limit
+7.9Vs
-12Vr +12Vr
-12Vr
BF001
toPincushion
Vcc
VDriveA
VDriveB
Page 16
Horizontal Deflection Troubleshooting(No Horizontal Drive)
1. Unsolder collector of TL35 (Horizontal Output Transistor).
2. Monitor the base of TL35 and press the power switch. The set will cycle untilpower is pushed again. A horizontal drive pulse should be present at the baseof TL35 while it is cycling.
3. If a drive pulse is present on the base of TL35, IV001 and the driver circuit areworking correctly. The problem is off the collector of TL35. Suspect Yoke,Yoke return circuit, pincushion, LL05 and the secondary side of LL05.
4. If the drive pulse is missing check for drive at pin 33 of IV001. If missing,suspect CV004, CV005, CV006, CV007, CV008, and RV001 components offof pins 15,16,17, and 19 of IV001. Corrupt data in the EEPROM could alsoprevent horizontal drive.
5. If drive pulses are present at pin 33 of IV001, check for them at the emitter ofTL031. If they are missing, disconnect DL062 and recheck. Drive pulses onthe emitter of TL031 with DL062 removed indicates that drive shutdown hasoccurred (See shutdown troubleshooting section). If drive is present at theemitter of TL031 with DL062 in circuit, check for drive at pin 3 of LL032 (LL033alt). If drive is present at pin 3 of LL032, suspect LL032 (LL033 alt) or aconnection problem with LL032 (LL033 alt). If missing go to next step.
6. Check for 13.0V at the collector of TL033 in standby mode. If missing,suspect RL037 and RL038 or TL033 (shorted). If present suspect DL035,RL034 or the +12Vr source.
NOTE: Pin 33 of IV001 (Horizontal Drive) will have 7.0Vdc when drive is missing.Possible causes of no Horizontal Drive:
• Corrupt EEPROM data
• +VCC missing at pins 14 and 39 of IV001
• Internal OSC off frequency. Capacitors on pins 15, 19, 16, and 17 of IV001effect PLL circuits.
• XRP detected at pin 36 of IV001
Page 17
Anode
Focus
Screen
IHVTLL05
5
8
Heater & XRP
Htr Return
13
12
11
101
9
IV001
33 Hout
CL30
TL31
TL060/061
TL62
TL33
LL32TL35
CL21 DL21
CL23,25,26RL25,26
DL25 LL26
BL005
+126V
RL34
DL35
RL37
RL38
CL35
RL41to 44
+181Vr
+33Vr
33V
-12Vr
+12VrHorizYoke
+12Vr 6
7
XRP
+13.1Vr
Pin 12LL05
1
3 6
4
RL07RL63
RL68
DL62
DL30
RL36
+7.9VsA
RV73
Vcc
14
+7.6VsD
36EHT
Pin 8LL05
Beam CurrentSense to PWR
IP050-3
TL50Buffer
RL12 DL12
CL13
RL10
DL10
CL11
LL40
DL01CL41
RL40
DL40TZ01DZ01,03,05
+7.6VsE
34
BF001
toPincushion
CBA
RL06RF07
from
321
123 BL003from
Pincushion CBA
Feed Back
Page 18
Alternate Vertical Troubleshooting InformationRepeat failure of the vertical output IC (IF001) can be difficult to find and expensive.The following information pertains to troubleshooting the vertical circuit with thevertical yoke disconnected. By unloading the vertical circuit it is possible to makechecks to the vertical output IC with out damaging it.
1. Disconnect the CRT socket and BF002 vertical yoke connector.
2. Using the Voltage chart, check for correct DC on all pins of IF001. If a voltageis not correct see the notes section of the Voltage chart for possible causes.
Pin No. Voltage Notes
1 +.7
Incorrect waveform from IV001 ormissing wavefrom. Check for open orshorted components between pin 21 ofIV001 and pin 1 of IF001. Checkfeedback resistor RF006.
2 +12.2Check for open circuit from +12Vrsource. Remember if the +12Vr ismissing the set will shutdown.
3 -13
This voltage is internally generated byIF001 and pin 4. If missing, suspectIF001 or pin 4 voltage missing.Common parts for incorrect voltageare: IF001, DF010, CF010.
4 -13Check DL010 and RL010 off pin 7 ofLL005. If RL010 is open check forshorts on the -12Vr source.
5 +1.6
This voltage is controlled by IF001 andthe input pins 1 and 7. If pins 1 and 7are correct suspect IF001, RF006,RF009, and RF007. Voltage Highindicates no drive to pins 1 and 7 ofIF001.
6 +11.8This voltage should be lower then pin 2.DF010 is a common failure along withIF001.
7 +.7
Incorrect waveform from IV001 ormissing wavefrom. Check for open orshorted components between pin 22 ofIV001 and pin 7 of IF001.
Page 19
ITC008 Pincushion Shutdown TroubleshootingPincushion shutdown occurs when TL101 (Pin Driver) pulls excessive currentthrough RL111. As the current increases so does the voltage. IL101 pin 12 monitorsthis voltage change and when the voltage exceeds the reference voltage found onpin 13 of IL101, IL101 (comparator) switches states and puts a high on pin 14. Thishigh is sensed by TL061 base turning it on and killing horizontal drive. To defeat thisshutdown circuit and troubleshoot the pincushion circuit, disconnect DL062.
Some of the common failures in the pincushion circuit have been:
• DL101
• DL102
• DL012
1. Verify the set is in pincushion shutdown by disconnecting BF001. If the setstays on, the pin circuit is causing the shutdown. If the set still shuts down theproblem is not with the pincushion circuit.
2. Unsolder DL062 cathode. This removes the shutdown protection. Usecaution when operating the set with DL062 disconnected. Short on-time isrecommended.
1
7
8
141213
32
910
6
IL101
51
2
3
1
2
3
BL101
RL150 RL134
PL143
RL131
RL132
RL107
RL106
PL140
RL108
DL138
RL138
CL138 LL122RL144
CL144
RL145
TL101CL122
DL121
DL122
BL103
DL119
CL12347V
RL113
RL112
RL111
DL118RL118
DL117
RL117
RL141PL141
+12.2Vpin
RL104
RL105
RL136
RL133
RL134
RL137
toCL021
andDL021
RL110
CL110
DL114
DL113
RL114
CL114
+12.2Vpin
Page 20
3. Monitor TL101 (Pin Driver) pin 3 for +18Vdc and 9.5Vp-p waveform and turnon the set. If the voltage is missing or incorrect, suspect he Pincushion CircuitBoard Assembly (CBA). If the voltage is high suspect an input signal problemor incorrect adjustment.
Note: This voltage can reach +130Vdc. Caution should be taken if thisvoltage exceeds +50V. +50V is the over voltage shutdown of the pincircuit. With DL062 disconnected the over voltage shutdown is alsodisabled. Running the set with voltage in excess of +50V can causeadditional damage. Short on time is highly recommended.
Tech-Tip: The Pincushion CBA is a replaceable module, however; troubleshootingthe module to component level can be accomplished. One of the common failureshas been cold solder connections on BL101. An oscilloscope and multimeter arerequired to isolate other problems. Keep in mind that the voltage readings found inthe schematic may not be exactly what your set has. The pincushion circuit hasadjustments for the different screen sizes therefore the voltages and waveforms canbe slightly different. For example: TL101 pin 3 shows to be 18.0V, our test set usedto develop this troubleshooting guide measured 20.8V. An acceptiable range for thevoltage on pin 3 of TL101 would be from +15V to +30V.
1
7
8
141213
32
910
6
IL101
51
2
3
1
2
3
BL101
RL150 RL134
PL143
RL131
RL132
RL107
RL106
PL140
RL108
DL138
RL138
CL138 LL122RL144
CL144
RL145
TL101CL122
DL121
DL122
BL103
DL119
CL12347V
RL113
RL112
RL111
DL118RL118
DL117
RL117
RL141PL141
+12.2Vpin
RL104
RL105
RL136
RL133
RL134
RL137
toCL021
andDL021
RL110
CL110
DL114
DL113
RL114
CL114
+12.2Vpin
Page 21
NOTES
TSG_ITC008