The Copy Is Blank; The Copy Is Solid Black - Canon NP6251 Service Manual

CHAPTER 11 TROUBLESHOOTING

21. The copy is blank.

Cause Step
Primary 1
charging
assembly
2
Developing 3
assembly
DC controller 4
PCB
Scanning lamp 5
Connector 6
Potential control 7
system
Developing bias 8
Main motor 9
(M1)

22. The copy is solid black.

Cause Step
1
11-84
COPYRIGHT © 1997 CANON INC.
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Checks
Is the primary charging assembly
set securely?
Is the charging wire or the grid
wire broken?
Is the developing assembly in firm
contact with the drum?
Does the blanking exposure lamp
remain OFF while the scanner is
moving forward?
Does the scanning lamp remain
ON during copying?
Are the connectors of the PCBs
connected securely?
Is the control by the potential
sensor executed normally?
Is the contact of the developing
bias firmly in place?
•Is the 1st copy blank halfway?
•Is the 1st copy blank, does the
2nd copy have displaced registra-
tion, and does a stationary jam
occur in this condition?
Checks
Does the scanning lamp remain
ON during copying?
CANON NP6350/NP6251 REV. 0 JULY 1997 PRINTED IN JAPAN (IMPRIME AU JAPON)
YES/NO Action
NO Set the charging
assembly.
YES String the charging wire
and the grid wire newly.
NO Check the developing
assembly locking lever.
NO Check the DC controller
PCB.
NO See "The scanning lamp
fails to turn ON."
NO Connect them securely.
NO Replace the potential
measurement unit.
NO Fix it in place.
NO Replace the main motor
(M1).
YES/NO Action
NO See "The scanning lamp
fails to turn on."