OKI C931

Jam occurs immediately after the paper feed is started.

Check condition of the paper running path

Check item	Check work	Actions to be taken at NG
Paper running path near the right side cover	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 paper entrance sensor 2 and the paper entrance sensor 3.	Check if shape and movement of the sensor levers have any abnormality or not.	Replace with a normal sensor lever.

Motor operation check

Check item	Check work	Actions to be taken at NG
Hopping motor	Confirm that the hopping motor works normally by using the Motor & Clutch Test of the self-diagnostic mode.	Replace the PU/CU PCB or hopping motor.
Hopping motor driver	Remove the HOPM connector of the PU/CU PCB and check the following at the connector side. 1 MΩ or more between pin-1/-2/-3/-4 and FG.	Replace the PU/ CU PCB.

Check the system connection

Check item	Check work	Actions to be taken at NG
Hopping motor drive cable	Check the connection condition of the cable. Visually check if the connector is connected in the half-way only or not, and check if the connector is inserted in a slanted angle or not. Also check that cables are assembled without any abnormality.	Normalize the connection condition. Replace with a normal cable.
Hopping motor drive cable	Check that any cable is not pinched during assembling of the printer. Remove the HOPM connector of the PU/CU PCB and check the following at the cable side. Short circuit between pin-1/-2/-3/-4 and FG	Replace the cable and normalize the assembled condition.
Hopping motor	Remove the HOPM connector of the PU/CU PCB and check that a resistance of 10Ω or less can be measured between pin-1 and pin- 2 and pin-3 and pin-4 respectively at the cable side.	Replace the hopping motor.