Canon PC980 Service Manual - Page 337

CHAPTER 11 TROUBLESHOOTING 21 The blanking lamp fails to turn on. Cause Side blanking PCB DC controller PCB Step 1 Checks Remove J106 from the DC control PCB, and set the meter range to 1 kΩ; then, connect the meter probes to J106-1 and -2 on the harness side. Is the meter reading about 20 Ω? YES/NO NO YES Action Check the harness; if normal, replace the side blanking PCB. Replace the DC controller PCB. 22 The scanning lamp fails to turn on. Cause Scanning lamp Fuse (FU1) Lamp DC controller PCB Composite power supply PCB Step 1 2 3 4 Checks Turn off the power switch, and disconnect the power plug from the power outlet.Is the scanning lamp (LA1) mounted correctly? Set the meter range to 1 kΩ, and connect the meter probes to both terminals of the fuse (FU1). Does the index of the meter swing? Disconnect the connector J910 from th ecomposite power supply PCB, and set the tester range to 1kΩ. Does the tester index swing when the probes are connected to J910-1 and J910-3 on the lamp side? Replace the DC controller PCB. Is the problem corrected? YES/NO Action NO Mount the scanning lamp correctly. NO Replace the fuse (FU1). NO Check the cable from the composite power supply PCB to the lamp; if normal, replace the lamp. YES End. NO Check the wiring between the DC controller PCB and the composite power supply PCB; if normal, replace the composite power supply PCB. 11-72 11-72 COPYRIGHT © 1999 CANON INC. CANON PC800s/900s REV.0 AUG. 1999 PRINTED IN JAPAN (IMPRIME AU JAPON)