what causes dark background on copies, but scans and prints look fine?

[sbtiti]

Re: what causes dark background on copies, but scans and prints look fine?

The scanner ribbon cable looks really good. I reseated the cable, but still have the problem. Any other ideas? Could the problem be in the main board where the ribbon cable connects? Any way to test the main board without substitution?

[Phil B.]

Re: what causes dark background on copies, but scans and prints look fine?

The scanner ribbon cable looks really good. I reseated the cable, but still have the problem. Any other ideas? Could the problem be in the main board where the ribbon cable connects? Any way to test the main board without substitution?

you say you cleaned the mirrors and glass... did you clean the white reference plate ( could be the 'shading' issue you mentioned if white plate reference is poor )

[sbtiti]

Re: what causes dark background on copies, but scans and prints look fine?

If the white reference plate is in the area between the DADF window and the flatbed window, it was cleaned since I cleaned the underside of the glass. I just checked it again and the white part looks good.

[Milo Wilson]

Re: what causes dark background on copies, but scans and prints look fine?

The cable could have fine cracks in it, so when it moves it could have little breaks in the lamp power.

[sbtiti]

Re: what causes dark background on copies, but scans and prints look fine?

I have performed many scans and copies since my last reply and it appears that the scanned images do not have a problem, so I am back to the original problem of determining why copies come out grey (mostly at the bottom third of the page), but print jobs, internal printed reports, and scans do NOT have the same issue. I think it must have something to do with the electical current draw of the scanner during a print cycle (copy) that affects the high voltage used for development. Would you recommend I replace the HVPS or is there a way to track down the culprit before swapping parts? I don't want to replace the HVPS if the problem is in the main power supply!
Thank you for any further help you can give me.

[rockdude]

Re: what causes dark background on copies, but scans and prints look fine?

Can you tell us if thier is "ANY" difference when you make copies on the glass as oppsed to the ADF?

If you make a copy of a "BLANK" white page both on the ADF and on the glass, is thier any difference in the density of the gray?

If you make 25 copies of a "BLANK" white page both on the glass and with the ADF, is thier any differnece from the first to the last copy?

Let us know?

[sbtiti]

Re: what causes dark background on copies, but scans and prints look fine?

There is a difference between the ADF copies and the flatbed copies, but I don't see a difference between first and last pages. I will attach a photo with 3 stacks of pages, the left is flatbed, the middle from ADF and the right from a print job. The print job is total white (printed a blank page) and the other two have darker shading on bottom 1/3 of page. The ADF one has strips of shading going vertical through the page as well as the more grey on the bottom third.

Not sure what the problem is, but the photo will not upload. I hope the explanation above will be good enough.
Thanks for your help. I may need to make a lower res. photo & see if it will upload.

[sbtiti]

Re: what causes dark background on copies, but scans and prints look fine?

Another try at attaching PIX

[sbtiti]

Re: what causes dark background on copies, but scans and prints look fine?

It has been a few days since my last update and maybe you all have given up on other ideas to help. I found a used main logic board on ebay so decided to give that a try. This unit has been off for a long time, but after installing the new (used) board it produced nothing but a dark page in all forms of printing. I put the original board back in and at first it had the same issue but after a few test pages it came back to the original symptoms as in the title of this post. I guess I'm at a loss of what to try next, unless I can get another 3635 to swap parts with.