Bizhub 420 strange behavior (jam)

[Guest]

A couple of days ago got my hands on 2 bizhub 420 ~90k/ ~400k and both manifest strange jams. Only on duplex print. One folds the paper before drum and sometimes the print gets out just right (if you fold back the paper you can read) and the other one folds the paper at the fuser exit. The one that jams at fuser exit behaves even stranger: with the first copy in a row everything is ok, the second page gets around 1/2 inch, 3rd more that an inch... delayed print as the drum was expecting the paper to arrive a bit earlier. Delay gets greater with every copy. After around 3-4 pages, the paper held in the reverse meets the paper getting out of the fuser. I have tried to swap most of the components with no luck at all.

I'm completely out of ideas... any help would be greatly appreciated!

[Copier Addict]

Re: Bizhub 420 strange behavior (jam)

I would say that the one that jams on duplexing needs to have the duplex clutches replaced. The one with the shifting image sounds like a failing registration clutch.
Hope this helps.

[EarthKmTech]

Re: Bizhub 420 strange behavior (jam)

this is not a strange jam at all.

if your experienced with these models you will recognise this fault instantly.

when you change both the adu clutches, make sure you clean out the excessive grease the assemblers slopped in there at the time of manufacture. Also make sure the duplex drive gear at the bottom of the door isnt missing teeth.

I recomend you perform the above work on both machines regardless as it will happen eventually anyway, registration clutch is indeed possible especially in poorly maintained machines with developer and toner spilling everywhere.

[RRodgers]

Re: Bizhub 420 strange behavior (jam)

Yeah, I've seen adu jam's due to clutches. Usually I just take them apart and clean them. They usually start working again.

[EduardBdod]

Re: Bizhub 420 strange behavior (jam)

Thanks! I will open them both today. In both their logs the jams never happened before. Could be the 2000 Km trip in a truck...

[Zeldaman]

Re: Bizhub 420 strange behavior (jam)

Hi there!
Also take a close look at the bushings of the timing-rollers! A few days ago, i had a smilar problem, one of the 4 bushings was worn out. After replacing it, the engine was running again without any jams. Hope this helps.
Greetings...

[CraigW]

Re: Bizhub 420 strange behavior (jam)

When doing 2-2 you can watch the paper through the open slots in adu section door (flashlight works best)

[JustManuals]

Re: Bizhub 420 strange behavior (jam)

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[EduardBdod]

Re: Bizhub 420 strange behavior (jam)

Just spent half of my day on those cursed devices! The one with misprint and jam just got promoted to "donor". Cleaned the clutches, registration sensors, first page is OK, second 2 inches out of page third just 1 inch... random. Jam is only on the fuser exit where the exit/return to ADU guide is. Paper getting out of the fuser meets paper going back in the ADU. Replaced the relay that moves the guide. Same problem. Too bad that this has only ~90k pages printed. On the second one, the jam is only in the imaging unit, like the the roller feeding the paper to the drum is not doing it's job. I was unable to get the clutch that moves the roller out. Seems like that was that was the part that the printer was built around. And by the way, what are those "timing-rollers"?
IMG_20131011_163225.jpgIMG_20131011_163247.jpg

[SmellsHot]

Re: Bizhub 420 strange behavior (jam)

First one you need to replace ADU clutches like what was mentioned previously....The 2nd machine, open your service manual and look for registration clutch. Wingin this clutch can be very difficult. It's pretty simple with some direction. A few screws here and there and it's out.

[EduardBdod]

Re: Bizhub 420 strange behavior (jam)

I'm getting the point now. Today i have replaced the assembly just beneath the drum (the one with 2 clutches and a sensor). Jam disappeared but the shifting image problem moved to this machine. I believe that the sensor can be guilty for this.