• Code: 3423-121.33
• Description: Fuser warm-up trouble
  Open fuser edge thermistor.
• Causes: • Controller board (CTLB) • Power supply unit (PU)
• Remedy: 1 Check the fuser cables JTHERM1 and JEXIT for proper connection to the CTLB. Reseat the cables if any abnormality is found. 2 Check the cable PCN5 for proper connection to power supply. Reseat the cables if any abnormality is found. 3 Check the cables JTHERM1, JEXIT and PCN5 for damage. Replace the fuser unit if any abnormality is found. 4 Check for resistance on the fuser cable. 1. Turn off the printer. 2. Remove the rear door and cover. 3. Disconnect the fuser cable connected to PCN5 of PU. 4. Check for approximate correct resistance on the fuser cable: 220V/43Om, 110V/10U, 100V/8Om

• Code: 3423-121.34
• Description: Fuser warm-up trouble
  Open fuser backup roll thermistor.
• Causes: • Controller board (CTLB) • Power supply unit (PU)
• Remedy: 1 Check the fuser cables JTHERM1 and JEXIT for proper connection to the CTLB. Reseat the cables if any abnormality is found. 2 Check the cable PCN5 for proper connection to power supply. Reseat the cables if any abnormality is found. 3 Check the cables JTHERM1, JEXIT and PCN5 for damage. Replace the fuser unit if any abnormality is found. 4 Check for resistance on the fuser cable. 1. Turn off the printer. 2. Remove the rear door and cover. 3. Disconnect the fuser cable connected to PCN5 of PU. 4. Check for approximate correct resistance on the fuser cable: 220V/43Om, 110V/10U, 100V/8Om

• Code: 3423-121.35
• Description: Fuser warm-up trouble
  Attempting to reboot after receiving a 121.34.
• Causes: • Controller board (CTLB) • Power supply unit (PU)
• Remedy: 1 Check the fuser cables JTHERM1 and JEXIT for proper connection to the CTLB. Reseat the cables if any abnormality is found. 2 Check the cable PCN5 for proper connection to power supply. Reseat the cables if any abnormality is found. 3 Check the cables JTHERM1, JEXIT and PCN5 for damage. Replace the fuser unit if any abnormality is found. 4 Check for resistance on the fuser cable. 1. Turn off the printer. 2. Remove the rear door and cover. 3. Disconnect the fuser cable connected to PCN5 of PU. 4. Check for approximate correct resistance on the fuser cable: 220V/43Om, 110V/10U, 100V/8Om

• Code: 3423-121.36
• Description: Fuser warm-up trouble
  Fuser did not heat to allow compression jog.
• Causes: • Controller board (CTLB) • Power supply unit (PU)
• Remedy: 1 Check the fuser cables JTHERM1 and JEXIT for proper connection to the CTLB. Reseat the cables if any abnormality is found. 2 Check the cable PCN5 for proper connection to power supply. Reseat the cables if any abnormality is found. 3 Check the cables JTHERM1, JEXIT and PCN5 for damage. Replace the fuser unit if any abnormality is found. 4 Check for resistance on the fuser cable. 1. Turn off the printer. 2. Remove the rear door and cover. 3. Disconnect the fuser cable connected to PCN5 of PU. 4. Check for approximate correct resistance on the fuser cable: 220V/43Om, 110V/10U, 100V/8Om

• Code: 3423-121.37
• Description: Fuser warm-up trouble
  Fuser heated faster than allowed during line voltage detection.
• Causes: • Controller board (CTLB) • Power supply unit (PU)
• Remedy: 1 Check the fuser cables JTHERM1 and JEXIT for proper connection to the CTLB. Reseat the cables if any abnormality is found. 2 Check the cable PCN5 for proper connection to power supply. Reseat the cables if any abnormality is found. 3 Check the cables JTHERM1, JEXIT and PCN5 for damage. Replace the fuser unit if any abnormality is found. 4 Check for resistance on the fuser cable. 1. Turn off the printer. 2. Remove the rear door and cover. 3. Disconnect the fuser cable connected to PCN5 of PU. 4. Check for approximate correct resistance on the fuser cable: 220V/43Om, 110V/10U, 100V/8Om

• Code: 4091-940.xx
• Description: Engine communication error
  Controller communication failure - the zero crossing signal used for fuser control in the low voltage (LV) power supply has failed, or the wrong low voltage power supply has been installed.
• Causes: • Power supply unit (PU) • Controller board (CTLB)
• Remedy: 1 Check the power cord for continuity. If necessary replace. 2 Make sure the nominal voltage source is within specification. • Low-voltage models: 100 to 127 V AC • High-voltage models: 220 to 240 V AC 3 Check if power supply cable is properly connected to the CTLB. Reseat the cables if any abnormality is found. 4 Measure the resistance between terminals A and D of the power supply socket. 1. Turn off the printer. 2. Remove the power cord. 3. Measure the resistance between terminals A and D of PU socket. 4. Is the resistance approximately 30 ohms? 5 Replace the PU if any abnormality is found in the measured resistance. 6 Replace the CTLB.

• Code: 4501-111.00
• Description: Laser malfunction
  Pel clock check failed.
• Causes: • Printhead (PH) • Controller board (CTLB)
• Remedy: 1 Check PH cables JLSU1 and J6 for proper connection. Reseat the cables if any abnormality is found. 2 Inspect PH cables and connectors. 3 Replace CTLB. 4 Replace PH.

• Code: 4501-111.01
• Description: Laser malfunction
  Downlevel ASIC detected.
• Causes: • Printhead (PH) • Controller board (CTLB)
• Remedy: 1 Check PH cables JLSU1 and J6 for proper connection. Reseat the cables if any abnormality is found. 2 Inspect PH cables and connectors. 3 Replace CTLB. 4 Replace PH.