Canon GP605 Service Manual page 644

<Checking the Developing Bias Output>
A
Turn on the potential control mechanism:
COPIER>OPTION>BODY>PO-CNT '1'
Measure the voltage DEV-DC-CNT
during copying at J510A-9 on the DC
controller PCB.
Select the following in service mode:
COPIER>DISPLAY>HV-STS>
BIAS(developing bias DC value).
Convert the reading taken during copying
(in V) into a control voltage as in
8 Potential Control Conversion Table.
Is the difference
between the actual
measurement of
DEV-DC-CNT and
BIAS in service
mode ±10%?
YES
Measure the voltage of J510A-8 on the
DC controller PCB.
Is the voltage about
5 V when the scanner
is moving forward?
YES
Check the developing assembly for
leakage. If normal, check the transfer
output.
13-52
NO
Replace the DC controller PCB.
NO
Replace the DC controller PCB.
<Checking the Transfer Output>
Is the toner image on
NO
the photosensitive
Replace the photosensitive drum.
drum before transfer
normal?
YES
Turn off the potential control mechanism:
COPIER>OPTION>BODY>PO-CNT '0'
Measure the voltage TR-CNT during
copying at J510A-6 on the DC controller
PCB.
Select the following in service mode:
COPIER>DISPLAY>HV-STS>TR
Convert the reading (µA) taken during
copying into a control voltage USING
8 Potential Control Conversion Table.
Is the difference between
NO
the actual measurement of
Replace the DC controller PCB.
TR-CNT and TR in service
mode ±10%?
YES
Replace the
high-voltage
YES
transformer. Is the
problem corrected?
NO
[1] Check the transfer charging assembly for leakage.
[2] Change the setting of the following in service
mode: COPIER>OPTION>BODY>FUZZY.
[3] Try replacing copy paper.
COPYRIGHT © 1999 CANON INC.
End.
CANON GP605/605V REV.0 JAN. 1999 PRINTED IN JAPAN (IMPRIME AU JAPON)