Samsung MultiXpress M537x series Service Manual page 335

6) Dark or Black page
Description : The printed image is dark or black.
Probable Cause
The charging roller in the imaging unit is defective.
The HVPS contact terminal is contaminated.
The output from the HVPS is abnormal.
The LSU is defective.
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Solution
Replace the imaging unit.
Clean the HVPS contact terminal.
Replace the HVPS board.
Replace the LSU.
4. Troubleshooting
4-199