Dell 1600n - Multifunction Laser Printer B/W Service Manual page 99

7.2.10 Vertical Line Getting Curved
• Description
When printing, vertical line gets curved.
Check and Cause
1. If the supply of +24v is unstable in the Main Control board
linking with LSU, check drive by Engine Test Mode :
Diagnostic Code 1 LSU Motor on.
Solution
1. Replace LSU.
2. Replace the Main Control board.
Troubleshooting
Service Manual
7-9