• Code: 544
• Description: Heating roller overheat: Center (hardware error)
  During stand-by mode or a print job, the detected heating roller temperature reaches 220°C.
• Causes: • Defective AC controller board • Defective IOB • Defective IPU • Defective fusing control system
• Remedy: 1. Replace the AC controller board. 2. Replace the IOB. 3. Replace the IPU. 4. Replace the fusing unit and reset the counter of the fusing unit using SP3-902-014. • The fusing unit cannot be used because an abnormal high temperature was detected. • After this SC occurs, the counter reset of the fusing unit should be done manually using SP3-902-014 because the counter reset is not done automatically.

• Code: 545
• Description: Fusing Heater error: Center
  The fusing heater keeps full power for 23 seconds or more.
• Causes: • Defective thermistors • Disconnected cables
• Remedy: 1. Replace the thermistors. 2. Check and replace the cables.

• Code: 547
• Description: Zero cross error
  • The zero cross signal is detected three times even though the heater relay is off when turning on the main power. • The zero cross signal is not detected for 3 seconds even though the heater relay is on after turning on the main power or closing the front door. • The detection error occurs twice or more in the 11 zero cross signal detections. This error is defined when the detected zero cross signal is 39 or less.
• Causes: • Defective fusing relay • Defective fusing relay circuit • Shorted +24V fuse on the PSU • Unstable power supply
• Remedy: 1. Check the power supply source. 2. Replace the +24V fuse on the PSU. 3. Replace the AC controller board.

• Code: 549
• Description: Fusing heater connection error
  The heating roller rotation sensor detects the target temperature as 50°C for 5 seconds or more after the fusing/paper exit motor has turned on.
• Causes: • Broken heater cables • Defective connectors
• Remedy: 1. Check the cable connection. 2. Replace the heater cables.

• Code: 551
• Description: Heating roller thermistor error
  The temperature at the end of the heating roller measured by the heating roller thermistor does not reach 0°C for 7 seconds.
• Causes: • Loose connection of pressure roller thermistor • Defective heating roller thermistor
• Remedy: 1. Check that the heating roller thermistor is firmly connected. 2. Replace the heating roller thermistor.

• Code: 552
• Description: Heating roller warm-up error 2
  • The heating roller temperature does not reach 80°C for 20 seconds after the inverter turned on. • The temperature at the end of the heating roller does not reach the ready temperature for 89 seconds after the fusing lamp turned on.
• Causes: • Defective heating roller thermistor • Defective inverter
• Remedy: 1. Check if the heating roller thermistor is firmly connected. 2. Replace the inverter.

• Code: 553
• Description: Heating roller overheat: End (software error)
  The detected heating roller temperature stays at 215°C or more for 1 second for 10 consecutive times.
• Causes: • Defective AC controller board • Defective IOB • Defective IPU
• Remedy: 1. Replace the AC controller board. 2. Replace the IOB. 3. Replace the IPU.

• Code: 554
• Description: Heating roller overheat : End (hardware error)
  The heating roller thermistor detects 220°C or more.
• Causes: • Defective AC controller board • Defective IOB • Defective IPU • Defective fusing control system
• Remedy: 1. Replace the AC controller board. 2. Replace the IOB. 3. Replace the IPU.