CP 4525dn paper jam when duplex printing

[Audun_Seierstad]

Single sided printing works fine, but frequently paper jam when printing using duplex module. Paper jam always in fuser. Somehow it seems like the sheet coming from the duplex unit for second page printing hits the fuser too early and enters the fuser before previous sheet leaves the fuser. The result is double sheet in fuser and paper jam as can be seen in attached picture. Error message "13.02.00 PAPER FEED 1, PAPER STOPPED JAM".

Occationally I also get the "13.13.00 DUPLEX PATH, PAPER STOPPED JAM" error, but paper path always empty when this event occur.

Why this timing issue? All rollers are cleaned or replaced. Works fine for a few pages, and then it can jam for every page. Most sensors have been manually tested using the manual sensor test routine as described in the Service Manual. No faulty sensors found. Fuser is at about 70% of expected lifetime.

[Valsimot]

When the printer prints the page and then it pulls back in for duplex it should not go through the fuser.  Check the flaps controlling the printed sheet returning back.

[Audun_Seierstad]

Thank you for your response!

The flap is OK and not the issue. What happens is the following:

1. Sheet 1 is picked up from drawer and passes through the fuser for first print.
2. Sheet 1 goes up to the reverse roller on top and returns back into printer via the duplex unit for its second print.
3. As Sheet 1 is on its way down through duplex unit for its second print, sheet 2 is picked up from drawer, heading for the fuser.
4. Sheet 1 follows the correct paper path, dotted line in graphic, and meet sheet 2 as sheet 2 is leaving the drawer on its way to the fuser for its first print.
5. Somehow sheet 1(Red line in graphic) comes a little early, or sheet 2(blue line in graphic) is a little late, because they meet with an overlap of about 10-15cm and with this overlap, both sheets enter the fuser at the same time, partly on top of each other.
6. The sensors probably detect the abnormal sheet length due to partly overlap and throw a paper jam message.

I am stuck here. Thought it could be slippery feed rollers, and changed/cleaned all of them. Then I thought it might be a faulty sensor, leaving the printer in the dark as to where the sheets are in the process, but diagnosing sensors have not revealed any faulty sensors. As the problem seems to build before the sheets enter the fuser, I doubt the fuser can be the cause. When printing on one side only, all works perfectly. Problem only occur when duplex printing. Using paper drawer 1 or drawer 2 makes no difference.

[Valsimot · Accepted solution]

I would blame it on the duplex registration assembly CC493-67917.

My theory is that the duplex re-pickup clutch ( CL1) is slipping when it should stop ( pause) the 1st sheet so that the 2nd sheet can pass to the fuser. The CL1 clutch is slipping and the 1st and 2nd page meet when they shouldn't.

If you can access the CL1 you can test it with 12V DC ( it has 2 wires) it should move freely ( rotate ) and when you apply voltage it should brake ( stop from rotating ).

It's has been a while since I had my eyes on that printer model but it might be that.

[Audun_Seierstad]

Thank you! Seems like your guidance lead me to the solution.

I removed the registration assembly and testet the clutch as you described. It worked, kind of, but it was "sticky". It engaged perfectly every time, but it did not always release. Often took some time and some turning on the wheels before it would release.

I took the clutch apart, blew out some dust and picked on it with a small screwdriver. Put it together and tested again. Now it seemed like the "stickyness" had gone. I remounted the registration assembly into the printer and did some test runs.

I have now duplex printed a 20 page document about 10-15 times without any paperjam, so I would say problem solved.

Thanks again!