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Exercise 7Exercise 7The Power SupplyThe Power Supply

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The Power Supply.The Power Supply.

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Power Supply Input VoltagePower Supply Input Voltage

100 to 125 VAC @ 60 Hz100 to 125 VAC @ 60 Hz 200 to 250VAC @ 50 Hz200 to 250VAC @ 50 Hz

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Motherboard Form FactorsMotherboard Form Factors

AT-TypeAT-Type

ATX-TypeATX-Type

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AT MotherboardAT Motherboard

12”12”

13.5”13.5”

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ATXATX Motherboard Motherboard

9.6 ”9.6 ”

12 ”12 ”

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AT Power DistributionAT Power Distribution

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Power Supply Output VoltagesPower Supply Output VoltagesAT-TypeAT-Type

+5 Volts+5 Volts

+12 Volts+12 Volts

-12 Volts-12 Volts

-5 Volts-5 Volts

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Power ConnectorPower Connector

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Edge View of Motherboard.Edge View of Motherboard.

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Voltage RegulatorVoltage Regulator

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P9P9P8P8

BlackWiresBlackWires

Motherboard Power ConnectorsMotherboard Power Connectors

P9P8

Back Probing P8 and P9Back Probing P8 and P9

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Some connectors are held in Some connectors are held in place by a latch.place by a latch.

LatchLatch

P9P9

GroundGround

GroundGround

+5V+5V

+5V+5V

+5V+5V-5V-5V

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P8P8

-12V-12V+12V+12V

GroundGround

GroundGround+5V+5V

Power Good Power Good

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The Power Good SignalThe Power Good Signal

+5 Volt signal generated by the power +5 Volt signal generated by the power supply.supply.

It indicates that the power supply has It indicates that the power supply has passed its self test and that its output passed its self test and that its output voltages have stabilized.voltages have stabilized.

Usually occurs within first 0.5 seconds.Usually occurs within first 0.5 seconds.

Prevents the system from running under Prevents the system from running under bad or unstable power conditions.bad or unstable power conditions.

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Large Molex ConnectorLarge Molex Connector

+5V

+12VGround

4-Pin MolexConnector

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Berg ConnectorBerg Connector

+5V

+12VGround

4-Pin BergConnector

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Grasp the connector

by the shell…

Never by the leads.

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ATX Power DistributionATX Power Distribution

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Power Supply Output VoltagesPower Supply Output VoltagesATX-TypeATX-Type

+5 Volts+5 Volts

+12 Volts+12 Volts

-12 Volts-12 Volts

-5 Volts-5 Volts

+3.3 Volts+3.3 Volts

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ATX Motherboard Power Connector

ATX Motherboard Power Connector

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PowerConnector

PowerConnector

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Replacing the Power SupplyReplacing the Power Supply

Disconnect the AC Power Cord.

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On-OffSwitch

On-OffSwitch

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Power toCD-ROM Drive

Power toCD-ROM Drive

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Power toHard Drive

Power toHard Drive

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Power toFloppy Drive

Power toFloppy Drive

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Power toMPU Fan

Power toMPU Fan

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Power toMotherboard

Power toMotherboard

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The Power Supplyis held in placeby four screws.

The Power Supplyis held in placeby four screws.

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PowerSupplyPowerSupply

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PowerSupplyShelf

PowerSupplyShelf

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Reinstall the power supply.Reinstall the power supply.