OKI C321dn

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.	Feed motor driving cord, image drum motor driving cord, belt motor, fuser driving cord 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	Pull out the CU/PU board BELT connector 1, and check the following at the side of the connector: Several MΩ between Pin 1 and frame ground Several MΩ between Pin 2 and frame ground Several MΩ between Pin 3 and frame ground Several MΩ between Pin 4 and frame ground Pull out the CU/PU board HOP connector 3, and check the following at the side of the connector: Several MΩ between pin-1 – FG Several MΩ between pin-2 – FG Several MΩ between pin-3 – FG Several MΩ between pin-4 – FG	Replace the CU/PU board.

Check the system connection

Check item	Check work	Actions to be taken at NG
Feed motor driving cord, image drum motor driving cord, belt motor, fuser driving cord	Check the connection condition of the cables. CU/PU board HOP connector 12, DC ID connector 2, DCHEAT connector 4, BELT connector 3. 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.
Feed motor driving cord, image drum motor driving cord, belt motor driving cord	Check that any cable is not pinched during assembling of the printer. Pull out the CU/PU board BELT connector 3, and check the following at the sides of the cords: Short circuit between pin-1 – FG Short circuit between pin-2 – FG Short circuit between pin-3 – FG Short circuit between pin-4 – FG Pull out the CU/PU board HOP connector, and check the following at the side of the cords: Short circuit between pin-1 – FG Short circuit between pin-2 – FG Short circuit between pin-3 – FG Short circuit between pin-4 – FG	Replace the cable with the good cable that normalizes the connection condition.
Feed motor, belt motor	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 HOP connector 1 Between pin-1-pin-2 Approx. 3.4Ω or approx. 5Ω. Between pin-3-pin-4 Approx. 3.4Ω or approx. 5Ω. CU/PU board BELT connector 3 Between pin-1-pin-2 Approx. 6.1Ω or approx. 3.5Ω. Between pin-3-pin-4 Approx. 6.1Ω or approx. 3.5Ω. Between pin-5-pin-6 Approx. 3.4Ω or approx. 5Ω. Between pin-7-pin-8 Approx. 3.4Ω or approx. 5Ω.	Replace paper feed motor, belt motor, ID Up motor.