Canon iR8500 Servise Manual page 324

In a zero-level check, a check is made to find out whether the microproces-
sor indicates 0 V when the drum surface potential is 0 V.
REF.
Using a zero-level check, the microprocessor on the DC control PCB and the measure-
ment unit may be checked.
In method 1, the condition of the level shift circuit on the DC controller PCB may be
checked while in method 2 the potential control circuit may be checked.
1. Method 1
1) Turn off the power switch.
2) Short J522-1 and -2 on the DC controller PCB with a jumper wire, and disconnect
connector J3 of the potential control PCB.
COPYRIGHT© 2001 CANON INC. 2000 2000 2000 2000 CANON iR8500 REV.0 MAR. 2001
CHAPTER 6 TROUBLESHOOTING
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