Power Supply

001 - START

Power off (unplug) the system unit. Check the power cord for continuity. Replace if necessary.

Check for the correct line voltage from the power outlet, and verify that the voltage selector switch (if present) is set to the correct voltage.

Power on the system unit.

002 - DOES THE POWER SUPPLY FAN RUN? (YES, GO TO STEP 003. NO, GO TO STEP 004.)

003 - DOES THE SYSTEM FAIL TO SHUT OFF WHEN THE ON/OFF SWITCH IS PRESSED? (YES, READ AHEAD. NO, GO TO STEP 005.)

You might have a damaged on/off switch cable assembly.

Disconnect the on/off switch cable assembly connector from the power supply connector and take an ohm reading.

Go to step 007.

004 -

Disconnect the power cord from the back of the system unit.

Disconnect all power and switch cable connectors from the system board and the power supply.

Disconnect the power connectors to all drives.

Connect any one of the power connector to system board or drive as power load for driving up power supply.

Reconnect the power cord and turn on the power supply.

005 - DOES THE POWER SUPPLY FAN RUN? (YES, READ AHEAD. NO, GO TO STEP 009)

With the system powered on and the power supply fan running, check the voltages of the power supply connectors for the system board and all drive connectors, as shown in the following figures.

68 IBM Desktop System HMM

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IBM 6644, 6645, 6646 manual Power Supply, Disconnect the power cord from the back of the system unit