• Code: 7901
• Description: Drum K EEPROM error
  No response is issued from the device in reading/writing for 5 ms or more and this problem is repeated five times successively. Mismatch of reading data from two locations occurs 8 times successively. Mismatch between writing data and reading data occurs 8 times successively.
• Causes: Defective connector cable or poor contact in the connector.
  Defective drum PWB K.
  
  
• Remedy: Defective 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 PWB K and front PWB (YC7) Front PWB (YC2) and engine PWB (YC10)
  Defective drum PWB K. Replace the drum unit K.

• Code: 7902
• Description: Drum C EEPROM error
  No response is issued from the device in reading/writing for 5 ms or more and this problem is repeated five times successively. Mismatch of reading data from two locations occurs 8 times successively. Mismatch between writing data and reading data occurs 8 times successively.
• Causes: Defective connector cable or poor contact in the connector.
  Defective drum PWB C.
• Remedy: Defective 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 PWB C and front PWB (YC12) Front PWB (YC2) and engine PWB (YC10)
  Defective drum PWB C. Replace the drum unit C.

• Code: 7903
• Description: Drum M EEPROM error
  No response is issued from the device in reading/writing for 5 ms or more and this problem is repeated five times successively. Mismatch of reading data from two locations occurs 8 times successively. Mismatch between writing data and reading data occurs 8 times successively.
• Causes: Defective connector cable or poor contact in the connector.
  Defective drum PWB M.
• Remedy: Defective 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 PWB M and front PWB (YC10) Front PWB (YC2) and engine PWB (YC10)
  Defective drum PWB M. Replace the drum unit M.

• Code: 7904
• Description: Drum Y EEPROM error
  No response is issued from the device in reading/writing for 5 ms or more and this problem is repeated five times successively. Mismatch of reading data from two locations occurs 8 times successively. Mismatch between writing data and reading data occurs 8 times successively.
• Causes: Defective connector cable or poor contact in the connector.
  Defective drum PWB Y.
• Remedy: Defective 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 PWB Y and front PWB (YC14) Front PWB (YC2) and engine PWB (YC10)
  Defective drum PWB Y. Replace the drum unit Y.

• Code: 7911
• Description: Developer unit K EEPROM error
  No response is issued from the device in reading/writing for 5 ms or more and this problem is repeated five times successively. Mismatch of reading data from two locations occurs 8 times successively. Mismatch between writing data and reading data occurs 8 times successively.
• Causes: Defective connector cable or poor contact in the connector.
  Defective developer unit K.
• Remedy: Defective 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 K and front PWB (YC9) Front PWB (YC2) and engine PWB (YC10)
  Defective developer unit K. Replace the developer unit K.

• Code: 7912
• Description: Developer unit C EEPROM error
  No response is issued from the device in reading/writing for 5 ms or more and this problem is repeated five times successively. Mismatch of reading data from two locations occurs 8 times successively. Mismatch between writing data and reading data occurs 8 times successively.
• Causes: Defective connector cable or poor contact in the connector.
  Defective developer unit C.
• Remedy: Defective 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 C and front PWB (YC13) Front PWB (YC2) and engine PWB (YC10)
  Defective developer unit C. Replace the developer unit C.

• Code: 7913
• Description: Developer unit M EEPROM error
  No response is issued from the device in reading/writing for 5 ms or more and this problem is repeated five times successively. Mismatch of reading data from two locations occurs 8 times successively. Mismatch between writing data and reading data occurs 8 times successively.
• Causes: Defective connector cable or poor contact in the connector.
  Defective developer unit M.
• Remedy: Defective 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 M and front PWB (YC11) Front PWB (YC2) and engine PWB (YC10)
  Defective developer unit M. Replace the developer unit M.

• Code: 7914
• Description: Developer unit Y EEPROM error
  No response is issued from the device in reading/writing for 5 ms or more and this problem is repeated five times successively. Mismatch of reading data from two locations occurs 8 times successively. Mismatch between writing data and reading data occurs 8 times successively.
• Causes: Defective connector cable or poor contact in the connector.
  Defective developer unit Y.
• Remedy: Defective 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 Y and front PWB (YC15) Front PWB (YC2) and engine PWB (YC10)
  Defective developer unit Y. Replace the developer unit Y.