Canon CLC 1120 Service Handbook page 57

Method 2
1) Turn off the power switch.
2) Remove the photosensitive drum unit.
3) Fit the potential sensor electrode (TKN-0197) to the potential sensor.
Caution:
When fitting the potential sensor electrode to the potential sensor, make sure that magenta of
the electrode will not come into contact with the potential sensor base.
4) Attach the clip of the jumper line to the potential sensor electrode.
Caution:
Be sure NOT to let the clip come into contact with the sensor cover. Further, be sure to allow
enough distance from the sensor window.
5) Connect one end of the jumper wire to the copier's chassis metal plate (GND) of the copier.
6) Insert the door switch actuator into the door switch assembly.
7) Turn on the power switch.
After turning on the power switch, do NOT touch the potential sensor assembly.
8) Check to make sure that DISPLAY>DPOT>DPOT is 100 ± 30 V in service mode.
Reference:
If the reading is as indicated in method 1 but not as indicated in method 2, suspect dirt on the
sensor or a fault in the potential measurement unit.
If the reading is not as indicated in method 1 and method 2, you may assume that the signal
path from the potential sensor unit to the CPU on the CPU PCB is normal.
9) Turn off the power switch.
10) Detach the potential sensor electrode.
11) Mount the photosensitive drum unit.
12) Turn on the power switch.
CHAPTER 2 STANDARDS AND ADJUSTMENTS
2-39