View Full Version : Miscellaneous Shadow image on print - why?

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07-18-2011, 07:59 AM
I have completely dismantled, cleaned and reassembled my cpp500 (two of em)and replaced one drum. Today I am getting a shadow image on my copies. The same image we are printing is shuffled to different areas of the print run. What causes this? It is almost as if the image is carried over on something and deposits a slight secondary repeat image. Any clues?

I am uploading a couple pictures as examples1087510876http://www.copytechnet.com/forums/images/misc/pencil.png

07-18-2011, 08:35 AM
I have seen this before...it is called ghosting I think. I'm trying really hard to remember what it's causes are since it's almost 3 in the morning. I'm almost certain it's a drum and charge issue. I think it occurs when one of the charges is too strong or the other is not strong enough...so maybe turn down the pre-charge and/or turn up the discharge.

But it might also be the laser intensity or charge (I forget the technical term). So for instance the new drum may be more sensitive than the old one so maybe decrease the laser power. Try those things and report back what happens. I could be wrong in this case but that's my guess for now. Did it do this before you cleaned the machine and changed the drum? Did you scrub the coronas/webs with alcohol? I've seen a few things happen after that is done...sometimes depending on the metal of the wire/web I think it takes the coating of the wires off.

One final quick check...make sure the fuser is clean and cleaning well.

07-18-2011, 07:09 PM

You said you changed 1 drum.. did you remove the 2 red screws, that hold the cleaning blade back, each on one end of the drum unit? If yes, did you apply powder on the drum before installing it? I guess your problem is, a cleaning blade isn't cleaning the drum properly.

07-18-2011, 09:15 PM
Hmm, two red screws?? Guess I better look into that one. As for dusting powder, we were told to blow yellow toner on the drum, is that right? And what is that for anyways?

07-18-2011, 09:33 PM
Okay, I have pulled out all the drums, checked the cleaner blades and all are touching the drums. Anything else I should look at before I put them back in?

07-18-2011, 09:46 PM
I didn't scrub the coronas, just wiped them lightly and blew them off with compressed air. I cleaned the fuser with methal hydrate. I will check the charge next, after I get it all up and running again

07-18-2011, 09:57 PM
Ok, before you put them back in, dust powder/ toner (that's okay too, but it's a lot messier) over each drum and gently rotate them all (manually, of course), to see if the powder/ toner is wiping of (I mean, if the cleaning blades do their job). Please try that and let me know what happened..

The two red screws are one at each end of the drums, on the "line" of the cleaning blade, right into 2 white plastic guides.

07-18-2011, 10:00 PM
Oh, and to answer your question/ doubt about the dusting powder/ toner, that's for "lubricating" (sorry, my english is pretty bad) the cleaning blades, at the beggining of a drums life. The copier does that while adjusting itself, but that's happening automatically and you don't see it. If the blade would run on the "dry" drum, it would "bend" and then the drum will never be cleaned - I really hope you understand my english... sorry

07-18-2011, 10:06 PM
I forgot to tell you, you can do the same thing with the powder/toner on the Transfer Belt too; check that out too, perhaps that part is not cleaned properly..

07-18-2011, 10:07 PM
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07-18-2011, 10:12 PM
Yeah, there were no red screws and the wiper blades seem to be working good. I am looking at all the 36 adjustments. Are they supposed to be done in any specific order?

07-18-2011, 10:19 PM
Yes, for the new drum, the adjustments are as follows:

1) Initial drum rotation
2) Auto Color registration adjustment
4) Automatic Gamma Adjustment (0)

That's it.

07-18-2011, 10:25 PM
Well, that might be part of it, I had removed the entire wiper unit from the transfer belt, disassembled it and cleaned it out. When you mentioned this I looked and one side was missing a spring. Took one off the old drum unit and am testing it again now

07-18-2011, 10:28 PM
Ok, if there was a spring missing on the cleaner unit of the belt, that's clearly what the problem was - without the springs, the blade doesn't "push" enough on to the belt. I hope it'll work know! :)

07-18-2011, 10:39 PM
The copies are really clean now but I still have that "shadow/ghosting" issue.
I did a bunch of adjustments, Auto drum potential, gamma and blade setting

07-18-2011, 10:56 PM
Ok, my last idea (I guess) is to swap the transfer belt unit between the 2 copiers (you said there are 2, right?); then, if the shadow is still there, swap the fusing units and if it still isn't dissappearing, I think there's something wrong with that drum you installed.. By swaping the parts, you can isolate the problem easier, in this case, when you get help from a long distance, on the internet :). Only make sure that you inter-change the parts back again, on their original copier, so to say..

07-18-2011, 10:57 PM
Did you try adjusting the laser beam intensity?

07-18-2011, 11:15 PM
One unit is Prince Rupert and the other is in Terrace, about 100 miles apart, so immediate test parts swapping isn't that easy, but we have done it. I have an extra transfer belt (old one).

No King, I didn't adjust the laser intensity (I don't think). Where do I find that function?

Here is another image, You can see it seems as is some black is repeating itself cause I can see it off the edges of the image area. Does this help10892

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