Canon NP6621, Service Handbook

Page: 76 / 146

4–12
TROUBLESHOOTING MALFUNCTIONS
Cause
Multifeeder
pick-up
clutch (CL3)
Paper guide
plate cam
Multifeeder
pick-up
solenoid
(SL2)
DC control-
ler PCB
Step
1
2
3
Checks
Select the multifeeder. Does the
multifeeder pick-up roller rotate when
the Copy Start key is pressed?
Press the Copy Start key; does the
paper guide plate shift up?
Connect the + probe to the J312B-8
on the DC controller. Does the voltage
change from about 24 V to about 0 V
when the Copy Start key is pressed?
Remedy
Check the wiring; if normal,
replace the CL3.
Check the position of the
paper guide plate cam and
the separation pad. As
necessary, adjust or replace.
Check the wiring; if normal,
replace SL2.
Replace the DC controller.
Yes/No
NO
YES
YES
NO
20 Pick-up operation fails (multifeeder).
Cause
Cable
Foreign
matter on
scanner
path
Composite
power
supply PCB
DC control-
ler PCB
Scanner
motor
Step
1
2
3
4
5
Checks
Is the scanner drive cable routed
correctly?
Is the scanner rail free of dirt and does
the scanner move smoothly when
pushed by hand?
Set the meter to the 50VDC range.
Doe the index of the meter point to 34
V when the + probe is connected to
J8-5 and the – probe is connected to
J8-6 on the composite power supply
PCB?
Replace the DC controller PCB. Is the
problem corrected?
Replace the scanner motor. Is the
problem corrected?
Remedy
Re-route the cable.
Check the scanner rail surface
for dirt and foreign matter or for
an object that comes into contact
with the scanner.
See “DC power is absent.”
End.
End.
Yes/No
NO
NO
NO
YES
YES
21 The scanner fails to move forward/in reverse.