[Electrical] Xerox J75 printing light gray background from edge to edge !?

[Colibri]

Hi guys, I'm new here and hope to get help from you because we have run out of ideas.
I own two copyshops in austria and we have several Xerox machines there: two 700, two 770 and and two J75. We maintain all the machines ourselves for years now.

On the J75 I noticed a few days ago a gray background from edge to edge on the complete sheet, no matter what size or thickness. I also noticed some random placed lighter dots.

First I was thinking that this problem comes from the corotron wire but after changing no improvement.
Then I started to change parts from our second J75:
-complete Drum-Developer-Unit (the whole part)
-complete IBT-Belt unit
-2nd BTR
-HVPS-Boards for Black on the left side of the machine, not the color-boards yet

...no improvement!

I tried to take a photo so you can see what I mean...

One thing I noticed that it sometimes gets better (you still can see it if you know where to look) and some copys later it gets worse again.

If anybody already had this problem and has an idea what can cause this please let me know. I'm thankful for every tip!

[jhalfhide]

Re: Xerox J75 printing light gray background from edge to edge !?

We've noticed this suddenly start across a range of papers and a range of customers, all using varying machines from J75, C60 and Versants. Customers have also said this has coincided with a change in quality from their paper provider. To cure this, we've been telling customers to create custom paper profiles on the machine and adjust the transfer volatage on the paper until the problem clears.

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[Colibri]

Re: Xerox J75 printing light gray background from edge to edge !?

Interesting, so you don't think that it is a faulty board or anything else from the hardware and we can fix this by adjusting parameters? The thing is, that we didn't change our paper or anything else. The problem came from one day to the next and is only on one machine of our two J75...

Greetings from Austria

[jhalfhide]

Re: Xerox J75 printing light gray background from edge to edge !?

A lot of our customers are all saying the same thing. One day the problem wasn't there, the next it was. I've had about a dozen of our clients, all over the UK and all over the space of a month, all start complaining of the same issue. All using different brands of paper, but all using their usual paper brand and supplier.

All of these have been cured using the transfer voltage setting on custom paper creation. I'd definitely try it. I think most only had to up it to about 105 to cure it

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[Colibri]

Re: Xerox J75 printing light gray background from edge to edge !?

Hi, just testet with different parameters for the the transfer voltage setting of a custom profile - without any big difference.
It got better with calibrating the machine but still noticeable white spots randomly spread over the sheet.
The interesting thing is that the affected J75 is from the UK - London

[rockdude]

Re: Xerox J75 printing light gray background from edge to edge !?

I have not had this happen on the J75, but have had the grey issue on similar models.

Sometime across entire page, sometimes just around the edge.

In my case replacement of High Voltage power supply solved problems.

Just a thought.

[adriansto]

Re: Xerox J75 printing light gray background from edge to edge !?

I have not had this happen on the J75, but have had the grey issue on similar models.

Sometime across entire page, sometimes just around the edge.

In my case replacement of High Voltage power supply solved problems.

Just a thought.

Bingo - the charge voltage on drum surface is not enough and toner particles from developer unit migrates on nonwritable area of the drum.

[Colibri]

Re: Xerox J75 printing light gray background from edge to edge !?

It works again and I cant 100% say what caused the problem.
Becaus we had a new black developer housing with extra new powder I said to myself lets give it a last try. I installed the new unit and also detached the plugs from both sides of the plug adapter. Maybe there was a little bit of corrosion? I dont know. But after that and with the new black developer housing it works like new without any background. The strange thing is that I swaped the whole drum-developer-unit two days ago from our second machine without any improvement???
Maybe it is better to be happy that it works again and not to think too much about why
Thanks to all for your help.