COPYRIGHT © 1996 CANON INC.
CANON NP6085 REV.0 JULY 1996 PRINTED IN JAPAN (IMPRIME AU JAPON)
3. OPERATIONS AND TIMING
3-178
w
Taking Advantage of Non-Automatic Control
Mode
Use non-automatic control mode to find out if
the cause of an image fault is on the input side or
the output side of the microprocessor on the DC
controller PCB.
If the problem is corrected somewhat in non-
automatic control mode, you can suspect a fault in
the potential measurement unit or the DC con-
troller PCB.
c. Zero-Level Check
A zero-level check may be used to see if the
surface potential control circuit is normal or other-
wise.
Reference:
In a zero-level check, a check is made to
find out whether the microprocessor identi-
fies 0 V when the surface potential is 0 V,
indicating whether the microprocessor on
the DC controller PCB and the measure-
ment unit are normal or faulty.
A zero-level check may be initiated using
either of two methods; use method 1 to check the
level shift circuit of the DC controller PCB, and
use method 2 to check the potential measurement
circuit.
q
Method 1
1) Turn OFF the power switch.
2) Remove the upper cover and the upper
right cover.
3) Disconnect the connector J4 from the
potential measurement PCB.
4) Short J132-1 and J132-2 on the DC con-
troller PCB with a jumper wire.
5) Insert the door switch actuator into the door
switch assembly, and turn ON the power.
6) Select the screen showing ‘DPOT’ (drum sur-
face potential) in service mode (
).
7) Check to make sure that DPOT on the
message display is 0 ±30 V.
If the value is not 0 ±30 V, suspect a fault
on the DC controller PCB.
8) Turn OFF the power switch, and remove
the door switch actuator.
9) Remove the jumper wire from the DC con-
troller PCB.
10)Connect the connector to J4 of the poten-
tial measurement PCB.
11)Install the upper cover and the upper right
cover.
12)Turn ON the power switch.
w
Method 2
1) Turn OFF the power switch.
2) Remove the blank exposure lamp assem-
bly.
3) Connect the connector of the potential sen-
sor.
4) Set the potential sensor checking electrode
(TKN-0197) to the potential sensor.
Figure 3-909
When setting the checking electrode to the
potential sensor, take care so that the mag-
net of the checking electrode will not touch
the potential sensor cover.
Figure 3-910
✻
5
✻
Note:
Magnet
Clip
Potential sensor
Checking electrode
Caution:
Potential sensor
Potential
sensor cover
Blank exposure
lamp
Magnets
Содержание NP6085
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