[C][M][Y][K] Led Failure - Xerox Phaser 7400 Service Manual

[C][M][Y][K] LED Failure

Applicable Status Codes:
Code U18: Yellow LED Failure
Code U19:
Magenta LED Failure
Code U20: Cyan LED Failure
Code U21: Black LED Failure
Initial Actions:
Cycle the printer's power.
If the problem persists follow the procedure below.
Troubleshooting Reference Table
Applicable Parts
LED Head, PL1.1.2
LEDPWR harness, PL12.1.20
LED Relay Board, PL12.1.34
YK LEDDATA harness, PL12.1.21
CM LEDDATA harness, PL12.1.22
Troubleshooting Procedure Table
Step Actions and Questions
1 Check LED Head.
Exchange the affected LED Head with
another LED Head.
Does the error move with the LED Head?
2 Ensure the LED Head harness is properly
connected and not damaged.
Is the wiring harness defective?
3 Check harness continuity between the LED
Head and the Engine Control Board.
Is there continuity?
4 Check harness continuity between the LED
Head and the LED Relay Board.
Is there continuity?
5 Check for +5 V to the LED Relay Board.
Disconnect the POWER connector.
Is there +5 V between POWER-1 <=>
ground?
6
Check for +5 V at the LVPS.
Disconnect CN1 from the LVPS.
Is there +5 V between CN1-1 and CN1-2?
3-108
Wiring and Plug/Jack References
Print Engine Map 1 (page 10-4)
Print Engine Map 3 (page 10-6)
Print Engine Map 13 (page 10-16)
Print Engine LED Heads (page 10-37)
Yes
Replace the LED
Head.
Reconnect or
replace wiring
harness.
Go to Step 4.
Go to Step 5.
Replace the LED
Relay Board
(page 8-126).
Replace the Engine
Control Board
(page 8-112).
Phaser 7400 Color Printer Service Manual
No
Go to Step 2.
Go to Step 3.
Replace the data
harness.
Replace the power
harness.
Go to Step 6.
Replace the LVPS
(page 8-121).