Canon CLBP-460PS, Service Manual, Page: 277 / 566

[ 2-12 ] Color missing
<Possible causes>
1) Go to step 13) if all the colors except black are missing.
2) Dirty toner detection port in the toner cartridge
Action: Clean the toner detection port in the cartridge of the missing color.
3) Poor contact in the developing bias contacts of the toner cartridge and the developing rotary.
Action: Clean the contacts of the developing rotary and toner cartridge of the missing color.
4) Defective developing cylinder (toner cartridge)
Action: Check the developing cylinder in the toner cartridge of the missing color, and
replace the defective toner cartridge.
5) Defective toner level detection light guide
Action: Clean the light guide of the missing color. Replace the guide if damaged.
6) Defective developing rotary developing bias contact part
Action: Replace the contact part, if the developing bias contact part in the developing rotary
does not move smoothly or is damaged.
7) Defective developing cylinder drive unit in the developing rotary
Action: Check the developing cylinder drive unit in the developing rotary. Replace any dam-
aged gears, etc.
8) Poor contact in the toner level sensor connector
Action: Reconnect the connectors between the toner level sensor, developing PCB, and DC
controller PCB correctly.
9) Defective toner level sensor
Action: Replace the toner level sensor.
10) Defective developing PCB
Action: Replace the developing PCB
11) Defective DC controller PCB
Action: Replace the DC controller PCB.
12) Defective ITB unit contact drive gear
Action: Check the drive gears that transmit contact movement to the ITB unit. Replace any
worn or fractured gear(s).
13) Defective ITB unit contact cam
Action: Check the cam that conducts the ITB unit contact operation. Replace the cam if
worn or cracked.
14) Defective ITB unit contact clutch
Action: Disconnect the clutch connector J103. Measure the resistance between cable con-
nector J103-2 (ITBCLON) and J103-1 (+24VA). If it is not about 160Éð, replace the
ITB unit contact clutch.
15) Poor contact in connectors
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CHAPTER 4