Malfunction Status Troubleshooting - Canon LBP-800 Service Manual

VI. MALFUNCTION STATUS TROUBLESHOOTING
Perform troubleshooting according to the malfunction diagnosis flowchart (Figure 4-1-1). If an
"malfunction status" is found, the defective part must be located and rectified by the following
procedure.
VI-1. Laser failure/BD failure
<Possible causes>
1) The laser shutter cannot be opened due to the damaged claw of the cartridge cover.
Action: Replace the cartridge cover.
2) Poor contact in the connectors in the laser scanner unit
Action: Reconnect connector J801F, J802F on the laser/scanner unit and connector J208F
on the engine controller PCB.
3) Defective laser/scanner unit
Action: Replace the laser/scanner unit if the voltage between connector J208M-5 and
J208M-6 on the engine controller PCB is about +5V and the voltage between con-
nector J208M-1 and J208M-4 is about +24V immediately after the printer is turned
ON.
4) Defective engine controller PCB
Action: Replace the engine controller PCB.
VI-2. Fixing unit failure
<Possible causes>
1) Poor contact in the connectors
Action: Reconnect connector J206F on the engine controller PCB.
2) Broken wire or short circuited thermistor.
Action: Turn OFF the power and remove the fixing unit from the printer. Measure the
resistance between connector J009-1 and J009-2 of the fixing unit. If the resist-
ance is not within the range from about 250 k
ture), replace the fixing film unit.
3) Broken wire of the heater or blown thermal fuse.
Action: Replace the fixing film unit if there is no conductivity between connector J102-1 and
J102-2 of the fixing unit when the fixing unit is out of the printer.
4) Defective engine controller PCB
Action: Replace the engine controller PCB.
VI-3. The printer cannot enter the READY mode and the "jam status" is output, although
a paper jam has not occurred.
<Possible causes>
1) Defective paper delivery sensor spring
Action: If the spring is not installed correctly, reinstall it correctly.
CHAPTER 4
to about 800 k (room tempera-
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