Description: Abnormally low fixing unit thermistor temperature • The fixing temperature remains below 90°C/194°F for 1 s.
Causes: Poor contact in the thermistor connector terminals. Broken fixing thermistor wire. Fixing thermistor installed incorrectly. Fixing thermostat triggered. Fixing heater M or S installed incorrectly. Broken fixing heater M or S wire.
Remedy: Reinsert the connector. Also check for continuity within the connector cable. If none, remedy or replace the cable. Measure the resistance. If it is ∞Ω, replace the fixing thermistor. Check and reinstall if necessary. Check for continuity. If none, replace the fixing thermostat. Check and reinstall if necessary. Check for continuity. If none, replace the fixing heater M or S.
Code: C640
Description: Zero-crossing signal problem • The engine PCB does not detect the zero-crossing signal for the time specified below. At power-on: 3 s Others: 5 s
Causes: Poor contact in the connector terminals. Defective power supply PCB. Defective engine PCB.
Remedy: Reinsert the connector. Also check for continuity within the connector cable. If none, remedy or replace the cable. Check if the zero-crossing signal is output from CN2-5 on the power supply PCB. If not, replace the power supply PCB. Replace the engine PCB if C640 is detected while CN2-5 on the power supply PCB outputs the zero-crossing signal.
Code: C780
Description: Broken external temperature thermistor • The input voltage is 0.5 V or less.
Causes: Poor contact in the humidity sensor connector terminals. Defective humidity sensor.
Remedy: Reinsert the connector. Also check for continuity within the connector cable. If none, remedy or replace the cable. Replace the drawer PCB and check for correct operation.
Code: C781
Description: Short-circuited external temperature thermistor • The input voltage is 4.5 V or more.
Causes: Defective humidity sensor. Poor contact in the humidity sensor connector terminals. Defective humidity sensor.
Remedy: Reinsert the connector. Also check for continuity within the connector cable. If none, remedy or replace the cable. Replace the drawer PCB and check for correct operation.