Symptom

Possible cause

Necessary actions

All the paper is black.

Incorrectly installed PCDU

Install the PCDU correctly.

Defective PCDU

Replace the PCDU.

Defective HVPS

Replace the HVPS.

Defective laser unit

Replace the laser unit.

Defective BiCU

Replace the BiCU.

Defective main board

Replace the main board.