OKI C831n

Jam occurs immediately after a paper is taken into printer.

Check condition of the paper running path

Check item	Check work	Actions to be taken at NG
Paper running path on the belt.	Remove the ID unit and check if paper is jammed or not in the paper running path.	Remove the jammed paper.

Check condition of the mechanical parts

Check item	Check work	Actions to be taken at NG
Check the sensor lever of the WR sensor.	Check if shape and movement of the sensor levers have any abnormality or not.	Replace the sensor lever with the good sensor lever.

Motor operation check

Check item	Check work	Actions to be taken at NG
Paper feed motor driver, belt motor driver and ID motor	Confirm that the paper feed motor, belt motor and ID motor work normally by using the Motor & Clutch Test of the self-diagnostic mode. Check if any load exists or not.	Replace the CU/PU board, or replace the defective motor among paper feed motor, belt motor and ID motor, or replace the ID unit or belt unit. If any attempt of using new ID unit or new belt unit as a trial is going to be made, be sure to use the System Maintenance Menu FUSE KEEP MODE.
Paper feed motor, belt motor	Remove the MOTERCL connector (1) of the CU/PU board and check the following at the connector side. Several MΩ between pin-1 – FG Several MΩ between pin-2 – FG Several MΩ between pin-3 – FG Several MΩ between pin-4 – FG Several MΩ between pin-5 – FG Several MΩ between pin-6 – FG Several MΩ between pin-7 – FG Several MΩ between pin-8 – FG	Replace the CU/PU board.

Check the system connection

Check item	Check work	Actions to be taken at NG
Paper feed motor drive cable, ID motor drive cable, belt motor drive cable, fuser motor drive cable	Check the connection condition of the cables. CU/PU board MOTERCL connector (1), DCID connector (3), DCHEAT connector , MOTERCL connector (1), RELAY connector (9). Check if the connector is connected in the halfway only or not, and check if the connector is inserted in a slanted angle or not. Check also that cables are assembled without any abnormality.	Normalize the connection condition. Replace the cable with the normal cable.
Paper feed motor drive cable, belt motor drive cable, hopping clutch drive cable	Check that any cable is not pinched during assembling of the printer. Remove the MOTERCL connector (1) of the CU/PU board and check the following at the connector side. Short circuit between pin-1 – FG Short circuit between pin-2 – FG Short circuit between pin-3 – FG Short circuit between pin-4 – FG Short circuit between pin-5 – FG Short circuit between pin-6 – FG Short circuit between pin-7 – FG Short circuit between pin-8 – FG Remove the HOPCL connector (2) of the CU/ PU board and check the following at the cable side. Short circuit between pin-1 – FG Short circuit between pin-2 – FG	Replace the cable with the good cable that normalizes the connection condition.
Paper feed motor, belt motor, hopping clutch	Remove the respective connectors from the board, and confirm that the following resistance exists between the corresponding pins, at the cable side. CU/PU board MOTERCL connector (1) Between pin-1 - pin-2: Approx. 3.4Ω Between pin-3 - pin-4: Approx. 3.4Ω Between pin-5 - pin-6: Approx. 3.4Ω Between pin-7 - pin-8: Approx. 3.4Ω CU/PU board HOPCL connector (2) Between pin-1 - pin-2: Approx. 240Ω	Replace the paper feed motor or ID Up motor.