Malfunction Troubleshooting - Canon LBP-1000 Service Manual

CHAPTER 4
V. MALFUNCTION TROUBLESHOOTING
If the factor of the malfunction is identified as "malfunction troubleshooting" by the malfunction
diagnosis flowchart (Figure 4-1-1), execute the followings and mend the malfunction.
V-1. No AC power
<Possible causes>
1. Blown fuse (FU201)
Action: Replace the fuse on the engine controller PCB.
2. Defective engine controller PCB
Action: Replace the engine controller PCB.
V-2. No DC power
<Possible causes>
1. No AC power is supplied.
Action: Check according to "V-1. No AC power."
2. Overcurrent/overvoltage detection circuit activated
Action: If the problem is not rectified after the power switch is turned OFF and then ON
again, find the cause of activation of the overcurrent/overvoltage detection circuit
on the engine controller PCB. Wait for two minutes or more before turning the
power back ON.
3. Defective wiring, DC load, or engine controller PCB
Action: Turn the power OFF. Check the wiring and the DC loads ahead of the engine con-
troller PCB. If problem is found, replace the relevant part. If no problem is found
with the wiring and DC loads, replace the engine controller PCB.
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