3-108 Phaser 7400 Color Printer 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 Wiring and Plug/Jack References
■ 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
■ 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)
Troubleshooting Procedure Table
Step Actions and Questions Yes No
1
Check LED Head.
Exchange the affected LED Head with
another LED Head.
Does the error move with the LED Head?
Replace the LED
Head.
Go to Step 2.
2
Ensure the LED Head harness is properly
connected and not damaged.
Is the wiring harness defective?
Reconnect or
replace wiring
harness.
Go to Step 3.
3
Check harness continuity between the LED
Head and the Engine Control Board.
Is there continuity?
Go to Step 4. Replace the data
harness.
4
Check harness continuity between the LED
Head and the LED Relay Board.
Is there continuity?
Go to Step 5. Replace the power
harness.
5
Check for +5 V to the LED Relay Board.
Disconnect the POWER connector.
Is there +5 V between POWER-1 <=>
ground?
Replace the LED
Relay Board
(
page 8-126).
Go to Step 6.
6
Check for +5 V at the LVPS.
Disconnect CN1 from the LVPS.
Is there +5 V between CN1-1 and CN1-2?
Replace the Engine
Control Board
(
page 8-112).
Replace the LVPS
(
page 8-121).
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