Thanks for the help. I will check the lamp and mirrors, however, I would think the scanned image would also show the problem if caused by the scanner unit. This may take me a few days to determine the outcome, but I will report back to this thread. Thanks again.
I have found that scans have a slight grey background, but nothing like the copies that seem worse the last 1/3 of the page. This darker 1/3 happens when using the flat bed glass for copies. I noticed that when the scan bar gets 2/3 the way down the page that the printer motor startup so it appears that this might be a clue to why the bottom 1/3 is darkest. It sounds like a power supply issue. What do think? Would you think the main power board or the high voltage power supply?
Thanks for any further help you can provide.
The scanner light is bright and even through the scan process.
so when the engine starts ( vibration ) you notice the problem..Originally Posted by sbtiti
could the PCU or DEVELOPER move and cause bias problems?
if it isn't laser... could be dev unit from the vibration is causing contact probs.. the old oki 4545 ( toshiba engine )
would do it until i added foam to front cover inside
IF it does it on internal prints AND Copies it's NOT the scanner
the scanner lamp ribbon cable usually goes bad by getting cracks and when the carriage moves, the ribbon cable connections will fluctuate the power to the lamp.
Print jobs look fine and so do internal reports. Copies are the poorest, but scans also have a slight background shading problem. I have cleaned the CCD mirror and both sides of the scanner glass to no avail. I will inspect the scanner ribbon cable for any defects. Thanks for the ideas.
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 )
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.
The cable could have fine cracks in it, so when it moves it could have little breaks in the lamp power.
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.
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