Taskalfa 250ci light grey background when color copying

[HaroldMenza]

Hi there,

I bought a second hand Taskalfa 250ci for private usage and am facing a strange problem: When I use the automatic feeder to make a color copy, every copy has a light grey background. As you can see from the attached image there is a grey background printed on the white page when I copied a completely blank white page.

What I don't understand is that this does not happen, when I color copy a page NOT USING the automatic feeder. I does not happen either when printing a colored document. It really only happens when using the automatic feeder for a color copy.

I have already tried to adapt the grey scale (sorry, English is not my mother tongue and I do not know the exact translations) and cleaned the glass, but no luck.

Do you have any idea how this could be solved?

Thank you!

[CWP]

Re: Taskalfa 250ci light grey background when color copying

Adjust the DP shading position through maintenance mode U068 (10871087 to enter maintenance mode, then enter 68 and press the green print button). The default setting is 0, try changing it to 10 + or - and see which one gets better, then you may have to go more or less. Exit maintenance mode by entering 001 then start, or turning the machine off and back on.

[HaroldMenza]

Re: Taskalfa 250ci light grey background when color copying

Thank you for your answer. I tried it but could not really resolve it. Adapt -10 did not change anything. Adapt +10 made it a bit better - at least the horizontal grey lines - (see this image of a color copy of a blank page http://www.imgbox.de/users/public/images/8tkv3Gthip.jpg) in general, however, a new dark grey line in the lower right corner appeared. So I tried +20 and it made it worse again, also the grey line.

Any other ideas? These grey lines do not appear when I use the automatic feeder to scan a color page to FTP for example. It really only appears when copying a color page. I am really helpless and I really need the color copy function.

[CWP]

Re: Taskalfa 250ci light grey background when color copying

If +10 made it better, try +5 or +15 and see if either of those are better than the +10 setting. Also make sure that the small scan glass to the left of the platen glass is clean. Also make certain that the document processor is closing correctly and the white pressure plate is moving freely and contacting that slit glass correctly. The optics are the same for DP scan and scan from glass. The only difference is that on one, the original moves and the other the scanner moves, but the optics and image path to the CCD are identical.

[HaroldMenza]

Re: Taskalfa 250ci light grey background when color copying

Thank you again very much for your kind assistance!

I tried +5 and +15 but neither of both made it significantly better than +10. The horizontal grey lines remain. The small glass on the left is clean, I cleaned it to be sure. This is a picture of it: http://www.imgbox.de/users/public/images/wWwxqXSlNT.jpg

The document processor is closing completely, the white pressure plate is also moving freely and also contacting the slit glass correctly as far as I can tell.

But I really do not understand how this is even possible: If there was a mechanical problem, shouldn't I have the same horizontal lines when copying black and white using the automatic feeder? Because when I do not color copy, but b/w I get a clear blank page without those lines. And also when I color scan using the automatic feeder, the resulting pdf or jpg file do not have those lines.

Edit: One more thing I found out: When I set the brightness to -1 (making it brighter) when color copying, the horizontal lines disappear, but reappear when setting brightness back to 0 or +1.

[blackcat4866]

Re: Taskalfa 250ci light grey background when color copying

The thing I haven't noticed in the previous posts is, have you cleaned the white level reference? Does your machine have the black mylar on the slit glass?

First, you might try moving the black mylar left ~1mm.

The adjustment that you have been doing shifts the position in which the scanner reads the white level reference values. What would be even better would be to have a clean white level reference, rather then randomly searching for a cleaner section. The white plate for the CCD is the painted white metal guide over the slit glass. You want it to be white, so don't use any chemical that will remove the white paint, just remove the dirt. Then try your U068 again at default values.

If you're still having the problem, you may want to calibrate the CCD with specific test patterns listed in the service manual. Yes, I know the test patterns are expensive, but that's how it's done. Read the manual and follow the procedure. =^..^=

[HaroldMenza]

Re: Taskalfa 250ci light grey background when color copying

Thank you very much!
Just to make sure that there are no language problems: What do you mean by "white level reference"?

Well, there is a black plastic "mylar" (had to look it up in my dictionnary) on the tiny glass to the left. But it was like that when I got it from the second hand dealer.
However, it is glued to the glass. How can I move it? When I try to lift it there are rests of sticky tape or some kind of glue left on the glass (I just tried to lift one corner).

I would even buy a new slit glass, if necessary and if there is one to purchase.

Thank you all for your patience with me!

[blackcat4866]

Re: Taskalfa 250ci light grey background when color copying

Yes, the black mylar is stuck on with two-sided tape. It may not come off neatly. You may need to buy a replacement mylar, and clean off the remaining adhesive from the old mylar. =^..^=

[HaroldMenza]

Re: Taskalfa 250ci light grey background when color copying

Any ideas where I can buy spare parts for the 250ci?

Can you take a picture of the "white reference level" that needs to be clean? The white plastic that is on the lid and placed on the slit glass when copying is already white.

Sorry, and again my question I cannot really understand: Why do the lines only appear when I color copy it and NOT when I copy it in black and white. If there was dirt or something on the slit glass, shouldn't the problem also be present when copying b/w?

[blackcat4866]

Re: Taskalfa 250ci light grey background when color copying

Take your pick:

https://www.google.com/search?q=303LL02500&ie=utf-8&oe=utf-8

part #: 303LL02500

You might take the time to fill out your biography information. Then I'd know what country you originate from.
=^..^=

[CWP]

Re: Taskalfa 250ci light grey background when color copying

Blackcat, you are a very wise and knowledgeable technician, but I beg to differ with you on this. U068 adjusts the DP scanning position - where the scanner stops under the slit glass and has nothing to do with white reference. U063 adjusts the shading position (where the scanner stops to check white reference), and you are correct in the requirement for it to be clean, however, if it were stained, you should see this in both scans from the glass as well as from the DP (single sided only, the single pass DP has its own white reference for CIS second side scanning).
Not bashing you, you help a LOT of technicians on this forum.

[blackcat4866]

Re: Taskalfa 250ci light grey background when color copying

Blackcat, you are a very wise and knowledgeable technician, but I beg to differ with you on this. U068 adjusts the DP scanning position - where the scanner stops under the slit glass and has nothing to do with white reference. U063 adjusts the shading position (where the scanner stops to check white reference), and you are correct in the requirement for it to be clean, however, if it were stained, you should see this in both scans from the glass as well as from the DP (single sided only, the single pass DP has its own white reference for CIS second side scanning).
Not bashing you, you help a LOT of technicians on this forum.

No problem CWP. Somewhere in the post I had switched mindset since this is the sort of thing you would usually see from the DP, not from the glass. The white plate for scanning OC (Sharp terminology for scanning Off the Contact glass) is under the index plate on the left edge of the glass. Remove the glass. The slit glass tends to stay attached by the foam seal, but it can unexpectedly drop off and break if you're not careful. So when you're lifting support both the glass and the slit glass together. Flip over the assembly to observe the condition of the white plate on the underside of the index plate. Often bits of paper and dirt can slip between the glass and the white plate.

The same still goes with calibrating the CCD though. =^..^=

[HaroldMenza]

Re: Taskalfa 250ci light grey background when color copying

In my case, the slit glass and the other bigger glass are two separate parts, they do not stick together. Is that a problem?

[blackcat4866]

Re: Taskalfa 250ci light grey background when color copying

In my case, the slit glass and the other bigger glass are two separate parts, they do not stick together. Is that a problem?

Not a problem, just unusual. It's actually much easier to handle the two pieces of glass separately if you can. =^..^=

[subaro]

Re: Taskalfa 250ci light grey background when color copying

The black stip on the slit or small glass is just for preventing paper jams and skews. So for testing purposes, it can be removed completely and the adf will work fine. if you start getting jams ect. just remember to put it back in place. In new setups they use to come separate in a bag which we had to install and sometimes would forget and machine worked fine.[ make sure to clean the glass of all residues when the strip is removed ] pass your fingers on the glass to test.
Logically, if the machine copy with no background from the adf in b/w mode, then the white reference sheet and glass is ok. Maybe one of the cym drum/dev has a problem, like drum not cleaning properly ect. But you said from the scanner glass is ok. So your entire description does not make sense really and you may have to do as blackcat suggested with scanner calibration.
Not sure of if this machine has the following function, but we do it in new machine colour setups. Toner curve , calibration, auto registration in that order. these are found under system menu.