Samsung ML-451 Series Service Manual page 222

4. Alignment and Troubleshooting
5) Light image
Description : The printed image is light, with no ghost.
Check and cause
Toner cartridge life is expired.
HVPS terminal is contaminated.
The output from the HVPS is abnormal.
6) Dark or Black page
Description : The printed image is dark or black.
Check and cause
Check if the high voltage terminal is contaminated.
The charging roller is defective.
The output from the HVPS is abnormal.
7) Uneven Density
Description : Print density is uneven between left and right.
Check and cause
The pressure force on the left and right springs of the
•
transfer roller is not even.
The springs are damaged.
•
The transfer roller is improperly installed.
•
4-121
Solution
Replace the toner cartridge.
Clean the contaminated terminal.
Replace the HVPS board.
Solution
Clean the high voltage terminal.
Replace the imaging unit.
Replace the HVPS board.
Solution
1) Remove the transfer roller Assy.
2) Check if the transfer roller Assy has any wrong part.
3) Replace the transfer roller Assy.
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