Canon NP6251 Service Manual page 579

A
B
Select Direct mode and 'GLEAM-5'
in service mode ( 3 ) .
* *
Does the
voltage vary between 0.5
NO
and 4 V during copying according Replace the DC controller PCB.
to the input of
*
'GLAM-5'?
YES
Check the lamp regulator or the
scanning lamp.
* Enter a value (minimum/maximum; within the
specified range), and press the user mode key;
*
then, measure the voltage during copying.
Ex.
GLAM-5 Reading
→
34 2.8V
→
139 3.9V
11-48
<Primary Output>
Select the primary power supply
limit notation. ( 1 ; 'PLMT')
* *
NO
Is 'PLMY' '1'?
YES
Select non-potential control.
( 4 ;'PO.CONT' '1')
* *
Measure the voltage during copying
between J114A-5 and A-13 on the
DC controller PCB.
(primary output)
Start service mode ( 1 ). Select
* *
'PC' (primary charging assembly
current). Convert the reading
during copying (µA) into its control
voltage according to 4 "Potential
Control Conversion Table."
Replace the DC controller PCB.
Is the
difference between the
NO
actual value in step B and the Replace the DC controller PCB.
reading of 'PC' ±10?
YES
Replace
the high-voltage transformer. YES
Is the problem
corrected?
NO
Replace the photosensitive drum.
<Developing Bias Output>
Select potential control.( 1
* *
'PO.CONT' '0')
Measure the voltage during
copying between J114A-2 and A-
13 on the DC controller PCB. (step
(developing bias DC
component)
Start service mode( 1 ). Select
* *
'BIAS' (developing bias DC value).
Convert the reading during copying
(unit: V) into its control voltage
according to 4 "Potential Control
Conversion Table."
Is the
difference between
the actual value in step C and
the reading under 'BIAS'
in service mode ±
10%?
YES
Measure the voltage between
J114A-3 and A-13 on the DC
controller PCB.
(developing bias AC component)
Does the
voltage change to about
5 V while the scanner
END
is moving forward
?
YES
Check the developing assembly for
leakage.
;
NO
Replace the DC controller PCB.
NO
Replace the DC controller PCB.