• Code: C510
• Description: Main charger problem • MC ALM signal is detected continuously for 400 ms when MC REM signal is turned on.
• Causes: Defective high-voltage transformer PCB. Leakage during main charging.
• Remedy: Replace the high-voltage transformer PCB. Check and clean the main charger assembly.

• Code: C511
• Description: Transfer charger belt high-voltage problem • TB ALM signal is detected continuously for 400 ms when TB REM signal is turned on.
• Causes: Defective transfer charger belt bias PCB. Leakage during transfer charger belt.
• Remedy: Replace the high-voltage transformer PCB. Check and clean the transfer charger belt.

• Code: C550
• Description: Drum surface potential sensor problem 1 The sensor output is 0.5 V or less when MC REM signal is turned on.
• Causes: Poor contact in the drum surface potential sensor connector theminals. Defective drum surface potential sensor. Defective engine PCB. Defective power source PCB.
• Remedy: Check the connection of connector CN7 on the engine PCB and the continuity across the connector terminals. Repair or replace if necessary. Check if 24 V DC is output from CN7-8 on the engine PCB. If it is, replace the drum surface potential sensor. Check if 24 V DC is output from CN7-8 on the engine PCB. If not, replace the engine PCB. Check if 24 V DC is supplied to CN10-5 on the engine PCB. If not, replace the power source PCB.

• Code: C551
• Description: Drum surface potential sensor problem 2 The sensor output is 4.5 V or more when the MC REM signal is turned on.
• Causes: Defective drum surface potential sensor.
• Remedy: Replace the drum surface potential sensor.

• Code: C560
• Description: Potential problem 1 Maximizing the grid output cannot set the potential.
• Causes: Deteriorated main charger. Grid or main charger shield is dirty. Defective high voltage transformer PCB. Defective engine PCB.
• Remedy: Check the main charger wire and replace it if necessary. Clean the grid or main charger shield if necessary. Replace the high voltage transformer PCB. Replace the engine PCB.

• Code: C561
• Description: Potential problem 2 Minimizing the grid output cannot set the potential.
• Causes: Defective high voltage transformer PCB.
• Remedy: Replace the high voltage transformer PCB.

• Code: C610
• Description: Broken fixing heater wire • The fixing temperature does not increase for 40 s after the fixing heaters have been turned on for warming up. • The fixing temperature remains below 50C/122F for 10 s continuously after the fixing heaters have been turned on during stabilization.
• Causes: Poor contact in the fixing unit thermistor connector terminals. Fixing unit thermistor installed incorrectly. Fixing unit thermostat triggered. Fixing unit heater M or S installed incorrectly. Broken fixing unit heater M or S wire.
• Remedy: Check the connection of connector CN5-12 on the engine PCB and the continuity across the connector terminals. Repair or replace if necessary. Check and reinstall if necessary. Check for continuity. If none, replace the fixing unit thermostat. Check and reinstall if necessary. Check for continuity. If none, replace the fixing unit heater M or S.

• Code: C620
• Description: Abnormally low fixing unit thermistor temperature • The fixing temperature remains below 120C/248F for 10 s.
• Causes: Poor contact in the fixing unit thermistor connector terminals. Broken fixing unit thermistor wire. Fixing unit thermistor installed incorrectly. Fixing unit thermostat triggered. Fixing unit heater M or S installed incorrectly. Broken fixing unit heater M or S wire.
• Remedy: Check the connection of connector CN5-12 on the engine PCB and the continuity across the connector terminals. Repair or replace if necessary. Measure the resistance. If it is , replace the fixing unit thermistor. Check and reinstall if necessary. Check for continuity. If none, replace the fixing unit thermostat. Check and reinstall if necessary. Check for continuity. If none, replace the fixing unit heater M or S.