Question about Xerox Phaser 7750DN Laser Printer

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Xerox 7750 Hi there, I read that you used to run gloss stock on a Xerox 7750 printer. Could i ask if you ever had problems with roller marks (we get a roller strip indent that can be seen when held at an angle to the light)? We are using Xerox Colortech 170gsm semi-gloss stock. In addition, we also get a grey haze in none toner areas (using the heavy weight and photo setting). Any advise you could give is appreciated. Thanks and regards, Matt

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  • Matty J Mar 12, 2008


    Thanks for your response.

    It doesn't appear to be the fuser. I have also checked the imaging units and transfer roller - all fairly new and no problems.

    I am printing from Tray 1 (MPT) and the marks appear as bands across the page (a dull sheen when compared to other areas of toner - like the toner has been squashed). I thought the marks were coming from the rollers, but in measuring them they don't appear to line up to any of the rollers. In addition, there is sometimes black dirt marks appearing on the printed pages - which appears to be toner. I have changed the black toner cartridge, but this failed to help.

    The printer is three years old and has only done 23k prints. The Accumulator Belt has not been changed in this time, however they are rated at a life span of 80k prints. Do you think this could be at fault? - I have inspected it with a torch and it does appear to have some small toner particles attached and minor scratches. Is there a safe way to clean this part?

    Other consumables -
    C - 17%
    M - 96%
    Y - 100%
    K - 100%

    Imaging units -
    C - 81%
    M - 100%
    Y - 85%
    K - 89%

    Transfer roller - 100%
    Belt cleaner - 100%
    Fuser - 76%
    Waste cartridge - okay.

    Thanks and regards,

  • Matty J Mar 13, 2008

    Hi there,
    Thanks again for all your help.

    I did some testing today and it looks like the black marks are coming from toner on the thin myler paper deflector near the tray one entry rollers (black marks appear before going into the fuser) - can this be cleaned?

    I have also changed the developer and cleaned the belt cleaner blade.

    Just a couple of further questions -
    1. Will the transfer belt still work okay if I clean it with iso. alcohol? I was previously told by Xerox to only gently wipe it with a clean tissue - if at all. It does have speckles of toner that look like they have been there for sometime (maybe creating the haze).
    2. I think you are correct that it is the small plastic rollers creating the marks. Will try different print settings tomorrow (slow it down and reduce the toner setting). Did you have this problem with gloss stock? If not, what stock did you use? It is odd that the machine is promoted as printing on gloss stock + I'm using Xerox media and still getting such poor results.

    Thanks again and regards,



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In what direction is the mark? Is the defect a dent in the paper,that repeats or is it a crease in the direction of the paper feed? If it is a dent that is repeating, the cause would be the transfix roller. If it is in the direction of paper feed, there may not be much you can do, most of those ceases you can see when held sideways like that come from the rollers edges. Just the normal crease that can be created by the end of the roller.
You can open the covers on the machine and make sure there is no excessive buildup of ink on any of the rollers. It is possible there is to much pressure on one of them, but with certain types of paper, there may not be much you can do. I will research it more and get back with you on that issue.
One thing you can try, (because your marks can be comming from a defective fuser), set the machine to print 4 or 5 pages, then shut it off or unplug the printer in mid run. Carefully look at the jammed pages to and see where in the process the crease is comming from. Take note and let me know please.
The gray haze seems to also indicate a possible fuser issue, but moreso, it sounds like the black housing is over toned. Most likely cause of that is a bad housing or bad developer. The developer in that machine will become worn and need replacing. It will restore the contrast and should resolve background issues.

Posted on Mar 11, 2008

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  • Rick Kasper Mar 11, 2008

    I forgot to mention. Paper is very very rarely a problem with a print quality issue.

  • Rick Kasper Mar 12, 2008

    I was looking over this again. I dragged out a 7700 I have in back, its a 7750 with some software changes.

    I really think the background issue you have is the developer. Where you replace the drum unit, inside there is a housing, the developer is a finlely ground plastic coated steel that carries the toner from teh housing to the drum. I have seen the developer fail and cause that type of problem. Mainly you mentioning the black spotting makes me strongly suspect that.

    Also have you removed the belt cleaner and wiped off the blade. It is on the rignt end of that accumulator assembly held on with 2 torx screws. Remove it and clean with a dry cloth.

    Now as to your roller marks. I am certain after running the machine, that those are comming from those small plastic rollers on the fuser assembly, with the fuser in the machine they are on the top of the fuser, small solid black plastic rolls. That is comming from the image not being 100 percent cooled when they come out of the fuser assembly. I don't believe there is anything you can do to 100 percent eliminate that, other then trying a new fuser.

    The accumulator belt, also knows as the transfer belt, there is almost zero chance that is a problem. You can clean it with s soft cloth dampened with some alcohol. It cleans well, but no real reason to do that unless something is really stuck to that belt.

    I have had them run 200,000 images with no issues. Actually other than just worn out with stripes from the cleaner and just age, I have never had one of those belts cause an actual quality problem. They are exceptionaly reliable

  • Rick Kasper Mar 13, 2008

    Yes that mylar strip can be cleaned. Just take caution not to put any kinks in it.

    Yeah, that transfer belt cleans well. Just be sure you use a very clean soft cloth.

    I have had labels stick to those belts many times. First time I was aprehensive about cleaning it, but I have cleaned glue off of those many many times with excellent results. Just don't use a lot o pressure, let the alcohol do the work. You are using the cloth to just remove the residue and remaining alcohol. I have done that many times with good results, I am certainly not replacing those belts a almost $300 a belt for glue and toner stucl to them.

    Just be sure you let the alcohol dry before you run it. So its not wetting the cleaning blade.

    No I doubt it is the gloss stock. You may want to try setting the machine to plain paper settings to lower the fuser temperature during fusing. I suspect the lines are simply the fact, that that paper is heated to 360 degrees F to melt the ink into the paper, and with a different texture the ink is not totally set when it gets to those rollers and it is sort of giving it an "ironed" look.

    Not confident you can eliminate that 100 percent.



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