Samsung CLX-8540ND Service Manual page 266

● Code : 04-004
04-007
● Symptom : After Yellow LD is on, Laser Beam Detect signal has not occurred or is irregular. (04-004)
After Magenta LD is on, Laser Beam Detect signal has not occurred or is irregular. (04-007)
● Possible Cause:
1. Harness is defective, Connector is not connected properly.
2. LSU is defective.
3. Engine Board is defective.
● Troubleshooting method :
1. Check the following.
-. Check if the Engine Board Harness is defective.
-. Check if the harness is connected to the 'LSU 1&2' Connector on Engine Board properly.
-. Check if the joint ①,② harness are connected properly.
Joint ①
2. Replace the LSU.
[Refer to 3.2.2 General Disassembly / LSU ]
3. If the problem persists after replacing the LSU, replace the Engine Board.
Troubleshooting
● Error message : LSU error: #04-004. Please turn off then on.
LSU error: #04-007. Please turn off then on.
(CN34, 32pin)
Joint ②
4-104
'LSU 1&2'