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Service Hints & Tips |
Document ID: GSMH-3A2LZY |
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This document is provided to IBM and our Business Partners to help sell and/or service IBM products. It is not to be distributed beyond that audience or used for any other purpose. |
IBM PC - Fails to power off or on
Applicable to: World-Wide
Symptom:
The PC/300 or PC/700 system fails to power off or on when the on/off switch button is depressed.
Problem Isolation Aids:
Before beginning the following procedure, remove any option cards and disconnect any I/O devices attached to the serial or parallel connectors and re-test. If the problem is eliminated by removing an adapter or device, this tip does not apply; suspect the device removed.
Check the following items:
1. Mechanical Problem:
Remove the top cover. If the system can be turned on and off with the top cover removed, look for a mechanical problem in the switch and button area and check the cover for proper fit and latching.
2. ON/OFF SWITCH:
The on/off switch is a SPST (single pole, single throw) switch and can be tested with an Ohm meter. Correct resistance will be open (infinity) with the switch released and closed (zero Ohms) with the switch depressed. If the switch fails this test, replace the switch assembly; if the switch tests good; continue.
3. POWER SUPPLY:
a. Remove the power cord from the power supply.
b. Remove the 3-pin power supply connector (J30) from the system board.
c. Reinstall the power cord. If the system powers up, replace the power supply; if the system does not power up, disconnect the power cord from the power supply; reinstall the 3-pin connector and power cord, and continue.
Note:
The 3-pin connector is a locking connector. If the latch is not depressed before attempting to remove the cable, the housing may pull loose from the system board. Reinstall the housing on the system board so the black wire in the 3-pin cable will connect to pin 1 on the system board connector.
4. RISER CARD:
Remove the riser card and test on/off function. the system may not function with the riser card removed; observe the power supply fan to determine if the system is on or off. If the fan can be turned off and on with the riser card removed, replace the riser card; if the system cannot be powered off with the riser removed, continue.
5. System Board:
If the above tests have not isolated the problem, replace the system board.
Fix:
Refer to the PC300/PC700 Hardware Maintenance Manual (S83G-7789 for FRU numbers and replace the appropriate FRU.
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Search Keywords |
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Hint Category |
Power | |
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Date Created |
03-09-96 | |
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Last Updated |
15-04-98 | |
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Revision Date |
13-04-99 | |
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Brand |
IBM PC | |
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Product Family |
PC 330, PC 350, PC 730, PC 750 | |
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Machine Type |
6571, 6573, 6575, 6576, 6577, 6581, 6583, 6585, 6586, 6587, 6875, 6876, 6877, 6885, 6886, 6887 | |
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Model |
various | |
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TypeModel |
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Retain Tip (if applicable) |
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Reverse Doclinks |