Lexmark C750 Service Manual - Page 82

5060-00x 127 Error code Backup roll thermistor or thermistor circuits are open The printer detects a problem in the fuser back up roll, circuits, fuser backup roll thermistor, engine board, or LVPS fuser control circuits. Step 1 Action and questions Turn the printer on and allow it to reach Ready. Note: The printer may not complete POR and post a 127 error message. Remove the fuser assembly from the printer and measure the voltage on connector J10-7 on the engine board. The voltage should measure approximately +3.3 V dc. Is the voltage correct? 2 Measure the voltage on pin 7 of the fuser DC control connector. See "Engine board" on page 5-7. The voltage should measure approximately +3.3 V dc. Is the voltage correct? Replace the fuser assembly. See "Fuser assembly removal" on page 4-31. Replace the LVPS. See "Low voltage power supply (LVPS) removal" on page 4-38. Yes Go to step 2 No Replace the engine board. See "Engine board removal" on page 4-29. 128 Error code Fuser hot roll is under temperature during standby. Step 1 Action and questions Turn the printer on to allow it to reach Ready. Note: The printer may not complete POR and continue to display a 128 error message. Remove the fuser assembly from the printer and measure the voltage on connector J10-6 on the engine board. The voltage should measure approximately +3.3 V dc. Is the voltage correct? 2 Measure the voltage on pin 6 of the fuser DC control connector on the LVPS. The voltage should measure approximately +3.3 V dc. Is the voltage correct? Replace the fuser assembly. See "Fuser assembly removal" on page 4-31. Replace the LVPS assembly. See "Low voltage power supply (LVPS) removal" on page 4-38. Yes Go to step 2 No Replace the engine board assembly. See "Engine board removal" on page 4-29. 2-48 Service Manual