• Code: C4000
• Description: Polygon motor synchronization problem • When the polygon motor starts, the motor does not become stable even after 20 s.
• Causes: Poor contact in the polygon motor connector terminals. Defective polygon motor. Defective power source PCB. Defective main PCB.
• Remedy: Reinsert the connector. Also check for continuity within the connector cable. If none, remedy or replace the cable. Replace the LSU. Check if 24 V DC is supplied to YC2-1 on the main PCB. If not, replace the power source PCB. Check if 24 V DC is output from YC8-10 on the main PCB. If not, replace the main PCB.

• Code: C4010
• Description: Polygon motor steady-state problem • When high-speed rotation from lowspeed rotation is requested, the motor does not become stable even after 20 s.
• Causes: Poor contact in the polygon motor connector terminals. Defective polygon motor. Defective power source PCB.
• Remedy: Reinsert the connector. Also check for continuity within the connector cable. If none, remedy or replace the cable. Replace the LSU. Check if 24 V DC is supplied to YC2-1 on the main PCB. If not, replace the power source PCB. Check if 24 V DC is output from YC8-10 on the main PCB. If not, replace the main PCB.

• Code: C4200
• Description: BD steady-state problem • The VTC detects a BD error for 600 ms after the polygon motor rotation has been stabilized.
• Causes: Defective laser diode. Defective polygon motor. Defective main PCB.
• Remedy: Replace the LSU. Replace the LSU. Replace the main PCB and check for correct operation.

• Code: C5300
• Description: Broken cleaning lamp wire While the cleaning lamp is on, the broken cleaning lamp wire detection signal is detected for 2 s continuously.
• Causes: Defective cleaning lamp. Defective main PCB.
• Remedy: Replace the cleaning lamp. Replace the main PCB and check for correct operation.

• Code: C6000
• Description: Broken fixing heater wire • When the power is turned on or at the start of fixing control from the sleep mode, 10 s after fixing heater M is turned on, the detected temperature of fixing thermistor 2 is lower than 40 C/104 F. • When the power is turned on or at the start of fixing control from the sleep mode, 7 s after fixing heater S is turned on, the detected temperature of fixing thermistor 1 is lower than 40C/104 F. • During standby, the detected temperatures of fixing thermistors 1 and 2 become lower than 60 °C/140F
• Causes: Poor contact in the fixing unit thermistor 1 or 2 connector terminals. Fixing unit thermistor 1 or 2 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 YC10 on the main 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: C6020
• Description: Abnormally high fixing unit thermistor temperature • Fixing thermistor 1 detects temperature 250 C/482 F or higher. • Fixing thermistor 2 detects temperature 210 C/410 F or higher.
• Causes: Shorted fixing unit thermistor 1 or 2. Broken fixing unit heater control circuit on the power source PCB.
• Remedy: Measure the resistance. If it is 0 Ω, replace the fixing unit thermistor 1 or 2. Replace the power source PCB.

• Code: C6050
• Description: Abnormally low fixing unit thermistor temperature • When only fixing heater M is on, fixing thermistor 2 detects temperature lower than 80 C/176 F during copying. • When fixing heater M and fixing heater S are on, fixing thermistor 2 detects temperature lower than 80 C/ 176 F or fixing thermistor 1 detects temperature lower than 100 C/212 F during copying.
• 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 YC10 on the main PCB and the continuity across the connector terminals. Repair or replace if necessary. Measure the resistance. If it is ∞Ω, 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.

• Code: C6400
• Description: Zero-crossing signal problem
  • The main PCB does not detect the zero-crossing signal (Z CROSS SIG) for the time specified below. At power-on: 5 s Others: 5 s
• Causes: Poor contact in the connector terminals. Defective power source PCB. Defective main PCB.
• Remedy: Check the connection of connectors YC1-3 on the main PCB and YC2-6 on the power source PCB, and the continuity across the connector terminals. Repair or replace if necessary. Check if the zero-crossing signal is output from YC2-6 on the power source PCB. If not, replace the power source PCB. Replace the main PCB if C6400 is detected while YC2-6 on the power source PCB outputs the zero-crossing signal.