• Code: C7612
• Description: Bias calibration read value error (Cyan) The ID sensors cannot properly read the patch density on the primary transfer belt when executing Calibration or Color Registration.
• Remedy: 1 Resetting the main power The ID sensor does not operate properly. Turn the power switch and the main power switch off . After 5s passes, turn the main power switch and the power switch on. 2 (In case if the printout is light) Checking the developer unit The developing roller does not contact with the drum. Switch the lock lever up and down and return the developer roller to the setting position. If the developer roller does not return due to the breakage of the lock lever or the failure of the developer roller pressure wire, replace the developer unit. Detaching and reattaching the Developer Unit 3 4 (In case if the printout is light) Cleaning / replacing the LSU. The laser does not output properly from the LSU. Or, LSU dustproof glass is dirty. Clean the LSU. If not repaired, replace it. Detaching and reattaching the LSU 5 (In case if the printout is light) Improving the condensation of the drum surface Condensation on the drum surface Execute the drum refresh. And next, set [On] at U339 [Drum heater] to turn on the drum heater. Adjustment/ Maintenanc e Menu (Operation Guide - Section 10) Maintenanc e Mode List 6 Cleaning the ID sensor The ID sensor is dirty. Clean the surface of the front and rear ID sensors. 7 Executing Calibration The last calibration failed. Execute U464 [Calib]. Maintenanc e Mode List 8 Checking the ID sensor shutter The ID sensor shutter does not operate properly. Execute U033 [ID Sensor]. If the ID sensor shutter does not operate properly, reattach the cleaning solenoid. Maintenanc e Mode List 9 Checking the primary transfer unit The primary transfer belt surface is dirty. Clean the surface of the primary transfer belt, or replace the primary transfer unit. Detaching and reattaching the Primary Transfer Unit 10 Checking the ID sensor The ID sensor is not properly attached, or the connector is not properly connected. Reattach the front and rear ID sensors and reconnect the connectors. 11 (When the image is too light) Checking the main high voltage PWB / transfer high voltage PWB Proper current does not flow as the main high voltage PWB or the contact point of the transfer high voltage PWB is faulty. Reattach the main high voltage PWB and the transfer high voltage PWB. 12 (When the image is too light) Checking the drum unit / developer unit / LSU The parts for the drum unit, developer unit and LSU is dirty or worn out. In case if the image is too light, clean the drum unit, developer unit and the LSU. Or, replace them. Maintenanc e parts replacemen t procedures 13 Firmware upgrade The firmware is not the latest version. Upgrade the firmware to the latest version. Firmware Update 14 Checking the connection The connector is not connected properly, or the wire is faulty. Clean the terminal of the following wire connectors and reconnect the connectors. If there is no continuity, replace the wire. . Front ID sensor and Rear ID sensor - Feed drive PWB . Feed drive PWB - Engine PWB Section 8 "PWBs" 15 Replacing the feed drive PWB The feed drive PWB is faulty. Replace the feed drive PWB. 16 Replacing the engine PWB The engine PWB is faulty. Replace the engine PWB. Detaching and reattaching the Engine PWB

• Code: C7613
• Description: Bias calibration read value error (Magenta) The ID sensors cannot properly read the patch density on the primary transfer belt when executing Calibration or Color Registration.
• Remedy: 1 Resetting the main power The ID sensor does not operate properly. Turn the power switch and the main power switch off . After 5s passes, turn the main power switch and the power switch on. 2 (In case if the printout is light) Checking the developer unit The developing roller does not contact with the drum. Switch the lock lever up and down and return the developer roller to the setting position. If the developer roller does not return due to the breakage of the lock lever or the failure of the developer roller pressure wire, replace the developer unit. Detaching and reattaching the Developer Unit 3 4 (In case if the printout is light) Cleaning / replacing the LSU. The laser does not output properly from the LSU. Or, LSU dustproof glass is dirty. Clean the LSU. If not repaired, replace it. Detaching and reattaching the LSU 5 (In case if the printout is light) Improving the condensation of the drum surface Condensation on the drum surface Execute the drum refresh. And next, set [On] at U339 [Drum heater] to turn on the drum heater. Adjustment/ Maintenanc e Menu (Operation Guide - Section 10) Maintenanc e Mode List 6 Cleaning the ID sensor The ID sensor is dirty. Clean the surface of the front and rear ID sensors. 7 Executing Calibration The last calibration failed. Execute U464 [Calib]. Maintenanc e Mode List 8 Checking the ID sensor shutter The ID sensor shutter does not operate properly. Execute U033 [ID Sensor]. If the ID sensor shutter does not operate properly, reattach the cleaning solenoid. Maintenanc e Mode List 9 Checking the primary transfer unit The primary transfer belt surface is dirty. Clean the surface of the primary transfer belt, or replace the primary transfer unit. Detaching and reattaching the Primary Transfer Unit 10 Checking the ID sensor The ID sensor is not properly attached, or the connector is not properly connected. Reattach the front and rear ID sensors and reconnect the connectors. 11 (When the image is too light) Checking the main high voltage PWB / transfer high voltage PWB Proper current does not flow as the main high voltage PWB or the contact point of the transfer high voltage PWB is faulty. Reattach the main high voltage PWB and the transfer high voltage PWB. 12 (When the image is too light) Checking the drum unit / developer unit / LSU The parts for the drum unit, developer unit and LSU is dirty or worn out. In case if the image is too light, clean the drum unit, developer unit and the LSU. Or, replace them. Maintenanc e parts replacemen t procedures 13 Firmware upgrade The firmware is not the latest version. Upgrade the firmware to the latest version. Firmware Update 14 Checking the connection The connector is not connected properly, or the wire is faulty. Clean the terminal of the following wire connectors and reconnect the connectors. If there is no continuity, replace the wire. . Front ID sensor and Rear ID sensor - Feed drive PWB . Feed drive PWB - Engine PWB Section 8 "PWBs" 15 Replacing the feed drive PWB The feed drive PWB is faulty. Replace the feed drive PWB. 16 Replacing the engine PWB The engine PWB is faulty. Replace the engine PWB. Detaching and reattaching the Engine PWB

• Code: C7614
• Description: Bias calibration read value error (Yellow) The ID sensors cannot properly read the patch density on the primary transfer belt when executing Calibration or Color Registration.
• Remedy: 1 Resetting the main power The ID sensor does not operate properly. Turn the power switch and the main power switch off . After 5s passes, turn the main power switch and the power switch on. 2 (In case if the printout is light) Checking the developer unit The developing roller does not contact with the drum. Switch the lock lever up and down and return the developer roller to the setting position. If the developer roller does not return due to the breakage of the lock lever or the failure of the developer roller pressure wire, replace the developer unit. Detaching and reattaching the Developer Unit 3 4 (In case if the printout is light) Cleaning / replacing the LSU. The laser does not output properly from the LSU. Or, LSU dustproof glass is dirty. Clean the LSU. If not repaired, replace it. Detaching and reattaching the LSU 5 (In case if the printout is light) Improving the condensation of the drum surface Condensation on the drum surface Execute the drum refresh. And next, set [On] at U339 [Drum heater] to turn on the drum heater. Adjustment/ Maintenanc e Menu (Operation Guide - Section 10) Maintenanc e Mode List 6 Cleaning the ID sensor The ID sensor is dirty. Clean the surface of the front and rear ID sensors. 7 Executing Calibration The last calibration failed. Execute U464 [Calib]. Maintenanc e Mode List 8 Checking the ID sensor shutter The ID sensor shutter does not operate properly. Execute U033 [ID Sensor]. If the ID sensor shutter does not operate properly, reattach the cleaning solenoid. Maintenanc e Mode List 9 Checking the primary transfer unit The primary transfer belt surface is dirty. Clean the surface of the primary transfer belt, or replace the primary transfer unit. Detaching and reattaching the Primary Transfer Unit 10 Checking the ID sensor The ID sensor is not properly attached, or the connector is not properly connected. Reattach the front and rear ID sensors and reconnect the connectors. 11 (When the image is too light) Checking the main high voltage PWB / transfer high voltage PWB Proper current does not flow as the main high voltage PWB or the contact point of the transfer high voltage PWB is faulty. Reattach the main high voltage PWB and the transfer high voltage PWB. 12 (When the image is too light) Checking the drum unit / developer unit / LSU The parts for the drum unit, developer unit and LSU is dirty or worn out. In case if the image is too light, clean the drum unit, developer unit and the LSU. Or, replace them. Maintenanc e parts replacemen t procedures 13 Firmware upgrade The firmware is not the latest version. Upgrade the firmware to the latest version. Firmware Update 14 Checking the connection The connector is not connected properly, or the wire is faulty. Clean the terminal of the following wire connectors and reconnect the connectors. If there is no continuity, replace the wire. . Front ID sensor and Rear ID sensor - Feed drive PWB . Feed drive PWB - Engine PWB Section 8 "PWBs" 15 Replacing the feed drive PWB The feed drive PWB is faulty. Replace the feed drive PWB. 16 Replacing the engine PWB The engine PWB is faulty. Replace the engine PWB. Detaching and reattaching the Engine PWB

• Code: C7620
• Description: Automatic color registration error 1. The patch print position on the primary transfer belt is not within the readable area by the ID sensor. 2. The primary transfer belt surface is dirty, or the patch print density is too light.
• Remedy: 1 Resetting the main power The ID sensor does not operate properly. Turn the power switch and the main power switch off . After 5s passes, turn the main power switch and the power switch on. 2 Executing Calibration The last calibration failed. Execute U464 [Calib]. Maintenanc e Mode List 3 (In case if the printout is light) Checking the developer unit The developing roller does not contact with the drum. Switch the lock lever up and down and return the developer roller to the setting position. If the developer roller does not return due to the breakage of the lock lever or the failure of the developer roller pressure wire, replace the developer unit. Detaching and reattaching the Developer Unit 4 5 (In case if the printout is light) Cleaning / replacing the LSU. The laser does not output properly from the LSU. Or, LSU dustproof glass is dirty. Clean the LSU. If not repaired, replace it. Detaching and reattaching the LSU 6 (In case if the printout is light) Improving the condensation of the drum surface Condensation on the drum surface Execute the drum refresh. And next, set [On] at U339 [Drum heater] to turn on the drum heater. Adjustment/ Maintenanc e Menu (Operation Guide - Section 10) Maintenanc e Mode List 7 Cleaning the ID sensor The ID sensor is dirty. Clean the surface of the front and rear ID sensors. 8 Checking the ID sensor shutter The ID sensor shutter does not operate properly. Execute U033 [ID Sensor]. If the ID sensor shutter does not operate properly, reattach the cleaning solenoid. Maintenanc e Mode List 9 Checking the primary transfer unit The primary transfer belt surface is dirty. Clean the surface of the primary transfer belt, or replace the primary transfer unit. Detaching and reattaching the Primary Transfer Unit 10 (When the image is too light) Checking the main high voltage PWB / transfer high voltage PWB Proper current does not flow as the main high voltage PWB or the contact point of the transfer high voltage PWB is faulty. Reattach the main high voltage PWB and the transfer high voltage PWB. 11 (When the color registration occurs) Checking the LSU / drum unit LSU or drum unit is not installed correct position. Or, LSU is faulty. If the color registration occurs, reinstall the LSU and the drum unit at the proper position. If not repaired, replace the LSU. Detaching and reattaching the Drum Unit Detaching and reattaching the LSU 12 Checking the ID sensor The ID sensor is not properly attached, or the connector is not properly connected. Reattach the front and rear ID sensors and reconnect the connectors. 13 Firmware upgrade The firmware is not the latest version. Upgrade the firmware to the latest version. Firmware Update 14 Checking the connection The connector is not connected properly, or the wire is faulty. Clean the terminal of the following wire connectors and reconnect the connectors. If there is no continuity, replace the wire. . Front ID sensor and Rear ID sensor - Feed drive PWB . Feed drive PWB - Engine PWB Section 8 "PWBs" 15 Replacing the feed drive PWB The feed drive PWB is faulty. Replace the feed drive PWB. 16 Replacing the engine PWB The engine PWB is faulty. Replace the engine PWB. Detaching and reattaching the Engine PWB

• Code: C7800
• Description: Outer thermistor broken The input sampling value of the temperature/humidity sensor (outer thermistor) is at the reference value or more.
• Remedy: 1 Checking the connection The connector is not connected properly, or the wire is faulty. Clean the terminal of the following wire connectors and reconnect the connectors. If there is no continuity, replace the wire. . Temperature/humidity sensor - Engine PWB Section 8 "PWBs" 2 Replacing the temperature/ humidity sensor The temperature/humidity sensor is faulty. Replace the temperature/ humidity sensor. 3 Firmware upgrade The firmware is not the latest version. Upgrade the engine firmware to the latest version Firmware Update 4 Replacing the engine PWB The engine PWB is faulty. Replace the engine PWB. Detaching and reattaching the Engine PWB

• Code: C7810
• Description: Outer thermistor short-circuited The input sampling value of the temperature/humidity sensor (outer thermistor) is at the reference value or less.
• Remedy: 1 Checking the connection The connector is not connected properly, or the wire is faulty. Clean the terminal of the following wire connectors and reconnect the connectors. If there is no continuity, replace the wire. . Temperature/humidity sensor - Engine PWB Section 8 "PWBs" 2 Replacing the temperature/ humidity sensor The temperature/humidity sensor is faulty. Replace the temperature/ humidity sensor. 3 Firmware upgrade The firmware is not the latest version. Upgrade the engine firmware to the latest version Firmware Update 4 Replacing the engine PWB The engine PWB is faulty. Replace the engine PWB. Detaching and reattaching the Engine PWB

• Code: C7901
• Description: Drum unit K EEPROM error 1. Five times consecutive detection of no response from the device for more than 5ms on reading / writing. 2. Data read in 2 places does not match 8 consecutive times. 3. Writing data and reading data does not match 8 consecutive times.
• Remedy: 1 Resetting the main power The data stored in the EEPROM in the drum unit is faulty. Turn the power switch and the main power switch off . After 5s passes, turn the main power switch and the power switch on. 2 Reinstalling the drum unit The drum unit is not properly installed. Reinstall drum unit K to connect the connector firmly. Detaching and reattaching the Drum Unit 3 Checking the connection The connector is not connected properly, or the wire is faulty. Clean the terminal of the following wire connectors and reconnect the connectors. If there is no continuity, replace the wire. . Drum unit - Drum/ developer relay PWB . Drum/ developer relay PWB - Feed image PWB . Feed image PWB - Engine PWB Section 8 "PWBs" 4 Drum unit replacement The EEPROM in the drum unit is faulty. Replace drum unit K. Detaching and reattaching the Drum Unit 5 Checking the connection of the EEPROMS in each unit EEPROM signal line of some units are faulty grounded. If the signal wire has a ground fault, replace it. . Signal wires (SCL, SDA) from the EEPROMs in the drum unit and the developer unit - Drum/developer relay PWB . Signal wires (SCL, SDA) from the EEPROMs in the primary transfer unit and the fuser unit - Feed image PWB Section 8 "PWBs" 6 Replacing the drum/developer relay PWB The drum/developer relay PWB is faulty. Replace the drum/developer relay PWB. Detaching and reattaching the Drum/ Developer relay PWB (Section 4 "Detaching and reattaching the waste toner box unit") 7 Firmware upgrade The firmware is not the latest version. Upgrade the engine firmware to the latest version Firmware Update 8 Replacing the feed image PWB The feed image PWB is faulty. Replace the feed image PWB. 9 Replacing the engine PWB The engine PWB is faulty. Replace the engine PWB. Detaching and reattaching the Engine PWB

• Code: C7902
• Description: Drum unit C EEPROM error Object: Color models 1. Five times consecutive detection of no response from the device for more than 5ms on reading / writing. 2. Data read in 2 places does not match 8 consecutive times. 3. Writing data and reading data does not match 8 consecutive times.
• Remedy: 1 Resetting the main power The data stored in the EEPROM in the drum unit is faulty. Turn the power switch and the main power switch off . After 5s passes, turn the main power switch and the power switch on. 2 Reinstalling the drum unit The drum unit is not properly installed. Reinstall drum unit C so that the connector firmly connects. Detaching and reattaching the Drum Unit 3 Checking the connection The connector is not connected properly, or the wire is faulty. Clean the terminal of the following wire connectors and reconnect the connectors. If there is no continuity, replace the wire. . Drum/developer relay PWB - Feed image PWB . Feed image PWB - Engine PWB Section 8 "PWBs" 4 Drum unit replacement The EEPROM in the drum unit is faulty. Replace drum unit C. Detaching and reattaching the Drum Unit 5 Replacing the drum/developer relay PWB The drum/developer relay PWB is faulty. Replace the drum/developer relay PWB. Detaching and reattaching the Drum/ Developer relay PWB (Section 4 "Detaching and reattaching the waste toner box unit") 6 Firmware upgrade The firmware is not the latest version. Upgrade the engine firmware to the latest version Firmware Update 7 Replacing the feed image PWB The feed image PWB is faulty. Replace the feed image PWB.