Service manual

4. Alignment and Troubleshooting

Service Manual

ML-551x / 651x series

4-133

Samsung Electronics

 Code

U2-1113

 Error message

LSU Unit Failure: #U2-1113. Turn off then on

 Symptom / Cause

LSU LD(Laser Beam Detect) signal is abnormal.

1. Harness connection error.

2. LSU is defective.

3. Main board is defective.

4. Engine board is defective.

 Troubleshooting method

1. Check if the C9 or C10 connector on the main board is connected properly.

2. Check if the LSU harness is defective.

3. Check if the LSU connector is connected properly. Reconnect it.

4. Turn the machine off then on.

5. If the problem persists, replace the LSU.

6. If the problem persists after replacing the LSU, remove the main board.

7. If the problem persists after replacing the main board, remove the engine board.

8. If you have the DVM, measure the voltage level for LD optical power control before step 5.

If it is normal, the value is between 0.6V~2.0V.

If the value is less than 0.5V, check the FFC cable between engine and main board.

Replace the FFC cable.