Canon GP215 Service Handbook page 44

TROUBLESHOOTING IMAGE PROBLEMS
4 The copy is foggy. (overall)
Cause Step
Scanner (dirt) 1
2
AGC 3
Developing 4
assembly
Developing bias 5
DC controller
PCB
3–8
Checks
Clean the scanning lamp,
reflecting plate, mirror, lens,
and dust-proofing glass. Is the
problem corrected?
Perform the Image Adjustment
Basic Procedure. Is the prob-
lem corrected?
Execute 'FUNCTION 15' in ser-
vice mode (*4*;
SERCT_GAMMA_NUM,
AGC_MEASURE).
• Open the *4* FUNCTION 15
screen, and press the Copy
Start key.
• Check the following:
SERCT_GAM AGC_MEA
MA_NUM SURE
0 ~–28.0uA
1 –28.1~
–36.5uA
2 –36.6~
–43.0uA
3 –43.1~
Is the value too different from
the above?
Is the developing cylinder insu-
lated from GND of the
machine?
Turn off the main power supply,
and disconnect the connector
J205 on the composite power
supply PCB. Check electrical
continuity between the connec-
tor J205-1 on the developing
assembly side and the side
plate of the machine.
Replace the composite power
supply PCB. Is the problem
corrected?
Yes/No Action
YES End.
YES End.
YES Set 'AGS NON' of 'OPTION'
(*5*) TO '1'.
If the resulting image is good,
keep the setting to '1' as an
emergency remedy.
However, be sure to take prop-
er action, as there may be a
problem on the image proces-
sor PCB or the DC controller
PCB.
NO Check the developing cylinder
and the parts around the
developing connector.
YES End.
NO Replace the DC controller
PCB.