Before removing the processor board, check the following areas:
- Check wires and connectors for defects
- Check for 8 to 10 VDC across 2 leads of the self test switch
- Press the self test switch- measure the voltage (voltage should be 0 VDC)
- Replace the self test switch, and test
If that doesn’t work, try the following steps:
- Replace the processor board with a “known good” one
- If the processor board seems bad, verify in the tester
- If the processor board is good, then replace the motherboard
- To repair the motherboard, use this diagram to isolate the bad trace
If the motherboard and processor board are good, then use this diagram to test for wire continuity
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