The Scanning Lamp Fails To Turn On - Canon NP6251 Service Manual

CHAPTER 11 TROUBLESHOOTING

43. The scanning lamp fails to turn on.

Cause Step
Connector 1
Lamp (LA1) 2
Thermal fuse 3
(FU1)
Lamp (LA1) 4
DC controller 5
PCB
Lamp regulator 6
(LR1)
Wiring
11-110
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Checks
Select 'SCAN LAMP' in service
mode ( ). Does the scanner
4
lamp remain on for 3 sec when
the user mode key is pressed?
Is the scanning lamp (LA1)
installed correctly?
Disconnect the power plug from
the power outlet, and remove the
thermal fuse. Is there electrical
continuity between both terminals
of the thermal fuse?
Set the meter to the Ω×1 range,
and disconnect the connector J4.
Does the index of the meter swing
when the probes of the meter are
connected to both terminals of the
lamp?
Set the meter to the 12VDC
range, and measure the voltage
between J111B-8 (+) and J111B-5
(–) on the DC controller PCB.
Does it change from about 5 to 0
V when the Copy Start key is
pressed?
Replace the lamp regulator. Is the
problem corrected?
CANON NP6350/NP6251 REV. 0 JULY 1997 PRINTED IN JAPAN (IMPRIME AU JAPON)
YES/NO Action
YES The connector may have
poor contact. Check the
connector.
NO Disconnect the power
plug, and install the lamp
correctly.
NO Replace the thermal
fuse.
Caution:
The lamp may have
turned on wrongly, the
fuse may be installed
wrongly, or the cooling
fan may be malfunc-
tioning. Make checks.
NO Replace the lamp.
NO Replace the DC
controller PCB.
YES End.
NO 1. Check the AC
harness from the
power supply switch
to the lamp regulator.
2. Check the DC
harness from the DC
controller PCB to the
lamp regulator.