Canon iR6570 series Service Manual page 481

Start
Disable the potential control mechanism
by entering '0' for the following:
COPIER>OPTIONAL>BODY>PO-CNT.
NO
Is the image
better?
YES
Turn off the main power
1. short CP33 on the controller PCB and GND.
2. disconnect the connector used between DC
controller PCBs of the potential control PCB.
turn on the main power
Make the following selections in service mode:
COPIER>DISPLAY>DPOT>DPOT-K
NO
Is the value between replace the DC
0 and 30?
controller PCB.
YES
turn off the main power
1. Disconnect the cable used to short the check pins
on the DC controller PCB.
2. Connect the connector used between the DC
controller PCBs of the potential control PCB.
turn on the main power
Check to make sure that the potential measurement
PCB is supplied with power, and check the potential
sensor using a checking electrode.
<Checking the Primary Output>
Turn off the potential control mechanism
by entering '0' for the following:
COPIER>OPTION>BODY>PO-CNT.
Measure the voltage HVT_PRIMARY of
J102A-11 on the DC controller PCB while
copying is under way.
Make the following selections in service mode
(primary charging assembly current level):
COPIER>DISPLAY>HV-STS>PRIMARY.
Convert the value (in uA) indicated while printing
is under way into a control voltage using the
Potential Control Conversion Table.
Is the difference
between the measured PR-CNT
and 'PRIMARY' shown in service
mode +/-10%?
YES
Try replacing the
high-voltage transformer. Is
the problem corrected?
NO
Try replacing the photosensitive drum.
If the problem is not corrected, go to
'Checking the Laser Output'.
F-13-10
NO
replace the DC
controller PCB.
YES
End
Chapter 13
13-9