Dell 1135N Service Manual page 134

Alignment and Troubleshooting
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 1. Replace LSU.
linking with LSU, check drive by 2. Replace the Main Control board.
DCU Mode : LSU Check -05-
LSU Motor on.
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Service Manual