Samsung ML-1640 Service Manual page 86

9) Vertical Line Getting Curved
• Description When printing, vertical line gets curved.
1. If the supply of +24v
is unstable in the Main Control board
linking with LSU, check drive by
DCU Mode : LSU Check -05-
Service Manual
Alignment & Troubleshooting
LSU Motor on.
1. Replace LSU.
2. Replace the Main Control board.
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Samsung Electronics