• Code: 7400
• Description: Developer unit non-installing error
  Sensor output value of 31 or less continuously for 5 s.
• Causes: Connector cable or poor contact in the connector. Toner sensor. Connect left PWB. Control PWB.
• Remedy: Connector cable or poor contact in the connector Reinsert the connector. Also check for continuity within the connector cable. If none, replace the cable. Developer unit and drum PWB (YC3) Drum PWB and drum connect PWB (YC1) Drum connect PWB and connect left PWB (YC3) Connect left PWB and control PWB (YC2)
  Toner sensor Replace the developer unit.
  Connect left PWB Replace the connect left PWB.
  Control PWB Replace the control PWB and check for correct operation.

• Code: 7410
• Description: Drum unit type mismatch error
  The drum PWB EEPROM does not communicate normally. Absence of the drum unit is detected.
• Causes: Connector cable or poor contact in the connector. Toner sensor. Connect left PWB. Control PWB.
• Remedy: Connector cable or poor contact in the connector Reinsert the connector. Also check for continuity within the connector cable. If none, replace the cable. Drum unit and drum connect PWB (YC1) Drum connect PWB and connect left PWB (YC3) Connect left PWB and control PWB (YC2)
  Toner sensor Replace the drum unit.
  Connect left PWB Replace the connect left PWB.
  Control PWB Replace the control PWB and check for correct operation.

• Code: 7800
• Description: Broken temperature sensor wire
  Input from temperature sensor is 1019 or more continuously for 160 ms. Input from temperature sensor is 930 or more continuously for 5 s.
• Causes: Temperature sensor. Control PWB.
• Remedy: Temperature sensor 1. Confirm that the wiring connector is firmly connected and, if necessary, connect the connector all the way in. Temperature sensor and control PWB (YC30) 2. If the wiring is disconnected, shorted or grounded, replace the wiring. 3. Replace the key right PWB.
  Control PWB 1. Check the control software and upgrade to the latest, if necessary. 2. Replace the control PWB and check for correct operation.

• Code: 7810
• Description: Short-circuited temperature sensor wire
  Input from temperature sensor is 31 or less continuously for 5 s.
• Causes: Temperature sensor. Control PWB.
• Remedy: Temperature sensor 1. Confirm that the wiring connector is firmly connected and, if necessary, connect the connector all the way in. Temperature sensor and control PWB (YC30) 2. If the wiring is disconnected, shorted or grounded, replace the wiring. 3. Replace the key right PWB.
  Control PWB 1. Check the control software and upgrade to the latest, if necessary. 2. Replace the control PWB and check for correct operation.

• Code: 7900
• Description: Drum EEPROM error
  No response is issued from the device in reading/writing for 5 ms or more and this problem is repeated 5 times successively. Mismatch of reading data from 2 locations occurs 8 times successively. Mismatch between writing data and reading data occurs 8 times successively.
• Causes: DR PWB. Connect left PWB. Control PWB.
• Remedy: DR PWB 1. Confirm that the wiring connector is firmly connected and, if necessary, connect the connector all the way in. DR PWB and drum connect PWB (YC1) Drum connect PWB and connect left PWB (YC3) Connect left PWB and control PWB (YC2) 2. If the wiring is disconnected, shorted or grounded, replace the wiring. 3. Replace the Drum unit.
  Connect left PWB Replace the connect left PWB.
  Control PWB 1. Check the control software and upgrade to the latest, if necessary. 2. Replace the control PWB and check for correct operation.

• Code: F000
• Description: Communication error between Control PWB and Operation PWB
• Causes: Control PWB. Operation PWB.
• Remedy: Control PWB 1. Turn the main power swtch off and after 5 seconds, then turn power on. 2. Check that the wirings and connetors between the control PWB and the operation panel PWB are normal. Operation PWB and control PWB (YC2002) 3. Check that the DIMM memories in the control PWB are well conducted and, if not, replace. 4. Execute U021initialize memory. 5. Replace the control PWB.
  Operation PWB Replace the operation PWB.

• Code: F010
• Description: Control PWB checksum error
• Causes: Control PWB.
• Remedy: Control PWB Turn the main power switch off/on to restart the machine. If the error is not resolved, replace control PWB and check for correct operation.

• Code: F020
• Description: Control PWB RAM check sum error
• Causes: Main memory (RAM).
• Remedy: Main memory (RAM) Turn the main power switch off/on to restart the machine. If the error is not resolved, replace control PWB and check for correct operation.