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Service Guide ML320/ML321
Chapter 4 Failure & Repair Analysis
RAP 01A:Operator Panel Lamps Do Not Light - Rev A, B, and C
START
Are the AC cables connected correctly?
NO
Connect the AC cables correctly.
Is the problem resolved?
YES
End of procedure.
NO
Go to A
YES
Go to A
A
Check the AC fuse on the primary side of the filter assembly. Is it open?
YES
Replace the fuse
Is the problem resolved?
YES
End of procedure.
NO
Go to B
NO
Go to B
B
Verify that the fuse holder is making proper contact with the fuse. Remove the fuse from the
holder. Gently squeeze both sides of the holder slightly towards each other. Reinsert the
fuse. Is the problem resolved?
YES
End of procedure.
NO
Are + 5 vdc and + 40 vdc supplied to the control board?
+ 5 vdc
Take the voltage reading between Pin 5 and Pin 9 of CN2 on the power
supply board.
+ 38 vdc
Take the voltage reading between Pin 1 and Pin 5 of CN2 on the power supply
board. Meter should read + 40 vdc.
YES
Replace the control board.
