C550i J9310 jams

[mascan42]

I have a problem machine that is constantly jamming when duplexing. The lead edge of the paper hits the duplex transport roll 3 (i.e. the first vertical one, at the top of the 2nd transfer section) and just stops, even though I can hear the lower duplex motor (M26) turning - it makes a very distinctive sound. I've already replaced the reverse assembly and the motor and the base PWB, and even the expansion control board (based on advice from an engineer who I don't think was actually listening to what I was saying). None of it has made any difference.

Another tech suggested that the motor was actually running in reverse (the lead edge of the paper looks a little indented where it hit the rolls), but after changing the motor and the board, there doesn't seem to be anything left. Any ideas?

[Albonline]

have you tried running from the main body cassettes? jam timing is very tight when duplexing. EG, ist feed gets multiple attempts single sided but not when duplexing. if the unit has a high meter count or has been running low quality paper ps actuators could be worn.

[tsbservice]

I had it once on C258 not high meter and it was ADU paper passage sensor actuator sometimes catching very slightly paper. Ended up with file a bit plastic to not interfere with sensor actuator. Though our was intermittent.

[allan]

The only way the stepper motor will run in reverse is if the connector is jammed in up side down(unlikely) or the driver chip that drives it is not enabled/disabled. Use a multi-meter to check if on of the four wire is pinched to ground the stepper will buzz but not turn. There is no error feed back from steppers only on the brush less 3 phase motors. Happy hunting.

[tsbservice]

After reading the manual it's easy. There are 2 sensors check them in sensor check, and 2 motors you replaced one so if sensors are OK it should be second motor M5.
Btw why you running troubleshooting process in reverse? I can't see it.

[mascan42]

It's not an intermittent problem. It's first time, every time. So I've replace both motors and the upper sensor. The paper stops before it gets anywhere near the lower sensor. And that's what the code says, that it didn't reach the lower sensor.

The paper stops every time in the exact same spot - right at the first vertical duplex roll. A second tech has looked at it as well, and came to the same conclusion.

[Scope]

Check the loop sensor, had issues with them before

[kingarthur]

I recently had a device constantly jamming when duplexing, due to the spring not quite on properly on the actuator for PS40, which is the 1st sensor of the duplex unit.

[mascan42]

Finally found the problem. There was a loose wire on the harness to the M26 motor.

[DK-tech]

I had this last week. Swapped out
AA2JR72700 Vertical Transport Assy and it worked.