[CQ] C353 - Ocasinal gray background on lead edge w/ developer

[mrwho]

Hello, guys and girls.

I've got a machine which sometimes throws out a copy/print with the first 90cm of the lead edge (about 35.5 inches) filled with a gray background.

Some data:

- It appears to the touch that the background has developer on it;
- The black text in the area affected disappears, only to be replaced with a void white area;
- The machine does it in BW and in Color - in color it only appears to affect the black IU
- The K IU is new, it has been replaced shortly before this began

As soon as I can, I'll scan some examples for you to check what I'm up against.

Cheers!

[mrwho]

Here are the examples I mentioned.

[dallas]

Change the PWB-MC (Printer Control Board)

[Albonline]

could be the image unit or a loose connection to it. or hv power supply. the image says loss of developer bias or could be print head. if the grey/developer area goes edge to edge its print head or printer control board

[DCPS]

Some questions:

Does the problem come only by the first copy after you have turned on the machine and the rest of the copies is almost good (you still have this phanomenon but not so noticable)? Is it a new machine and did the problem come suddenly?

[mrwho]

Some questions:

Does the problem come only by the first copy after you have turned on the machine and the rest of the copies is almost good (you still have this phanomenon but not so noticable)? Is it a new machine and did the problem come suddenly?

Although the machine is now brand new, it doesn't have too many copies on it (I don't have a counter handy right now, but I can post it tomorrow when I get back).

The problem usually ocurs on the first copy after a pause (either when turning on the machine or after a 15 minute pause after the last job).

I was meant to go back there this afternoon, but my car broke down. I'm going back there first thing tomorrow, and then I'll post back.

Thanks for your replies.

[mrwho]

After a whole morning here, I'm not closer to the solution. I checked the HV contacts and everything seems fine.

It seems to me that I'm dealing with a bias failure, although I'm baffled at the fact that it happens only on such specific conditions (print/copy after a long pause).

[DCPS]

This was my case at that time. Machine had about 3000 copies despite this problem. As you can see the problem looks much more intensive during the first copy. After that it will be almost good. The examples are with 150% density. Above that you have to look very carefully to see the error after the first copy.

The cables between EL-C and EL-K where swapped from factory during the installation! On CN47 on PRCB it should look like that: Pin2 EL-Y, Pin4 EL-M, Pin6 EL-C and Pin8 EL-K. In my case it was like that: Pin2 EL-Y, Pin4 EL-M, Pin6 EL-K, Pin8 EL-C. I reconnected them correct on the erase lamps and the problem was gone. Can you proof it? It might was a bad serie on a bad day

[mrwho]

I think we found out the solution to this thanks to this thread I started a while ago. Turns out I was the fool responsible for this in the first place.

As soon as the machine is up and running, I'll post some confirmation replies.

[mrwho]

It was indeed the ICP5 mentioned on the thread I told about in the previous post. Silly me not checking everything thoroughly the first time over.

Have a nice weekend!

[Stirton.M]

This looks like a very unique issue.

At first glance, bias would be my immediate guess. But the negative image on the right side of the page (lead edge) tells me that something else is wrong and that the laser write process has reversed into a negative image.

Just out of curiosity, if you were to copy a good page off the glass and set the machine to give you a negative image as an output, what does the output document look like? If it is the opposite of the images you posted, I would say replace the PRCB/MCB. It might even be memory related.

[mrwho]

First of all, I should've explained (for those who didn't check the other thread's attachment) that the ICP5 controls the belt resetting (the original problem I had, again on the other thread), the fusing unit resetting and the drum's erasure lamps - which is what caused all this trouble.

Answering Stirton's question, I never really tried that exact test, but I did try some other thing: When trying to troubleshoot the issue, I disabled the black IU's charge corona (using scotch tape over the contacts) and tried to make a copy. Without the corona, the machine should've output an entirely black sheet (if I'm mistaken, please correct me), but in reality the output came black on the left (the "good" area) and with the text partially visible on the right. This led me to believe that the erasure lamp wasn't working because the drum still had some charge from previous copies.

I'm sorry if this sound confusing - even now I'm reading it and I'm getting dizzy. Good thing the weekend's here! \o/

[Stirton.M]

Ya, sorry about the answer. I was going based on your earlier post before you put in the details about the ICP. I had opened up this thread to reply earlier, was interrupted and came back after. And obviously right after you found the cause and solution by a mere couple minutes.

Tape eh? I'll have to add that idea to my mental toolbox.

[mrwho]

No worries, I'm just glad this is over. Thanks for every feedback.

About the tape, I don't see the need to add it - every customer of mine has some lying around.

[mrwho]

Also kudos to DCPS who also guessed what was wrong - already rep'd you, sorry for not aknowledging your post earlier.