Resetting the Logic Board

Resetting the logic board can resolve many system problems (refer to "Symptom Charts" for examples). Whenever you have a unit that fails to power up, you should follow this procedure before replacing any modules.

1 Unplug the computer.

2 Remove the logic board. (Refer to the Take Apart chapter for instructions on how to remove the logic board.)

3 Using a small flat-blade screwdriver, pry open the latch at the end of the battery holder and lift off the battery holder cover.

4 Remove the battery from its holder.

5 Verify the power supply cable is disconnected from the logic board and then press the Power On button. (See "Logic Board Diagram" later in this chapter to locate the Power On button.)

6 Wait at least 10 minutes before replacing the battery. Make sure the battery is installed in the correct +/-direction.

7 Reassemble the computer and test the unit.

Note: This procedure resets the computer's PRAM. Be sure to check the computer's time/date and other system parameter settings afterwards.

Note: If this procedure resolves the problem, claim an adjustment on an SRO. If not, replace the defective component and DO NOT claim the adjustment procedure.


The Power Macintosh 8500 and WS 8550 computers offer Fast SCSI support on the internal SCSI connector, which provides for significantly enhanced data throughput. The internal SCSI bus on these computers supports transfer rates up to 10 MB/sec.

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