OKI C321dn

Jam occurs immediately after the paper feed is started. (1st tray)

Check condition of the paper running path

Check item	Check work	Actions to be taken at NG
Paper running path of the front unit	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
Hopping sensor and IN sensor lever check	Check the sensor lever shapes and operations for any problem.	Replace the sensor lever(s) with proper one(s).
Check the separator assemblies of the feed roller, the pickup roller and the tray.	Check if any foreign materials such as paper dust on the surface of the feed roller or of the pickup roller or not.	Remove the foreign material.
	Check if the feed roller or the pickup roller has worn out or not.	Replace the separator assemblies of the feed roller, pickup roller and tray.

Motor operation check

Check item	Check work	Actions to be taken at NG
Paper feed motor	Confirm that the paper feed motor works normally by using the Motor & Clutch Test of the self-diagnostic mode.	Replace the PU board or the paper feed motor.
Paper feed motor driver	Pull out the CU/PU board HOPSIZE connector 1, and check the following at the side of the connector. Several M between pin-1 – FG. Several M between pin-2 – FG. Several M between pin-3 – FG. Several M between pin-4 – 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	Check the connection condition of the cable. 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.	Replace the cable with the good cable that normalizes the connection condition.
Paper feed motor drive cable	Check that any cable is not pinched during assembling of the printer. Pull out the CU/PU board HOPSIZE connector 1, and check the following at the side of the connector. 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.
Paper feed motor	Remove the HOPSIZE connector 1 of the PU board and check that approx. 3.4Ω can be measured between pin-1 -pin-2 at the cable end, and that approx. 5Ω can be measured between pin-3 -pin-4 respectively.	Replace the paper feed motor.

Solenoid operation check

Check item	Check work	Actions to be taken at NG
Feed clutch	Confirm that the paper feed solenoid works normally by using the Motor & Clutch Test of the self-diagnostic mode. Pull out the cassette for the rollers to be seen, and check operation.	Replace the CU/PU board or the feed solenoid.

Check the system connection

Check item	Check work	Actions to be taken at NG
Feed clutch cord	Check the connection condition of the cable. 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.	Replace the cable with the good cable that normalizes the connection condition.
Cord for feed clutch	Check that any cable is not pinched during assembling of the printer. Pull out the CU/PU board HOC connector 14, and check the following at the side of the cord.	Replace the clutch and properly assemble appropriate parts.