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  1. #1
    Senior Tech 100+ Posts MVPunisher's Avatar
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    bizhub 751 spewing toner.

    So I have a 751 that consistently is not accepting a developer change. When it does take one it is fine and it will last right through the pm cycle. Sometimes it takes me a few changes in a row before it accepts one.

    And what I mean by accepts one is- if it does not I will get a call back in 5k because it will be severly overtoned and spewing everywhere. Ive done toner control sensor, I have decreased the tcr %. I have enough of these in the field to be confident I am not doing something wrong. All my adjustments are "ok" after replacing.

    Hv unit or prcb or something maybe? Any suggestions?


  2. #2
    Service Manager 10,000+ Posts
    bizhub 751 spewing toner.

    JustManuals's Avatar
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    Lightbulb Re: bizhub 751 spewing toner.

    This Parts & Service Manual can now be purchased for $12.77 and downloaded immediately after payment from:


    http://www.justmanuals.com


    paul@justmanuals.com



  3. #3
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    Re: bizhub 751 spewing toner.

    I can't resist,

    You mean to tell me you have 601/751's that don't dump.

    My normal checks are Bias on dev unit, Drum voltage, drum ground, and T&S mylars. I also have had a T&S unit cause dumping on a brand new machine.

    We have not been able to completely eliminate dumping on these machines.

    Last edited by Frostwolf; 11-12-2013 at 07:26 PM. Reason: Formatting of post

  4. #4
    Senior Tech 100+ Posts MVPunisher's Avatar
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    Re: bizhub 751 spewing toner.

    Yea I hear ya on the dumping. This one just on a totally different level. Makes it like 5 k before dev is so overtoned you can't even copy. Thats like 2 day lol. Little different than my normal dev spew.


  5. #5
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    bizhub 751 spewing toner.

    Discountcopiers's Avatar
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    Re: bizhub 751 spewing toner.

    THE MAGNETIC ANGLE ON THE MAIN MAG-ROLL MAY HAVE SHIFTED. IF YO HAVE SEVERAL CONTRACT CUSTOMERS TRY SWAPING DEV UNIT TO9 SEE IF THE PROBLEM FOLLOWS THE UNIT. i KNOW ALL OF YOU ARE SHAKING YOUR HEAD BECAUSE OF DOWN TIME....BUT iF YOU TAKE THE (SUSPECTED)BAD UNIT OUT OF THE MACHINE AT CUSTOMER CLOSING TIME AND SWAP IT WITH OUT WITH THE OTHER MACHINE AT FIRST THING THE NEXT MORNING (WHEN YOUR OTHER CONTRACT CUSTOMER OPENS)..DO YOUR SET UP. GO BACK TO THE FIRST AND TRY A SET UP... YOU HAVE JUST LIMITED THE AMOUNT OF SUSPECTED CAUSES.
    ITS WORTH A TRY.


  6. #6
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    Re: bizhub 751 spewing toner.

    Quote Originally Posted by MVPunisher View Post
    So I have a 751 that consistently is not accepting a developer change. When it does take one it is fine and it will last right through the pm cycle. Sometimes it takes me a few changes in a row before it accepts one.

    And what I mean by accepts one is- if it does not I will get a call back in 5k because it will be severly overtoned and spewing everywhere. Ive done toner control sensor, I have decreased the tcr %. I have enough of these in the field to be confident I am not doing something wrong. All my adjustments are "ok" after replacing.

    Hv unit or prcb or something maybe? Any suggestions?

    here it is 2015 and I still get to work on these! joy joy..

    MV.. i have a whole host of these alos doing the same .. within 5K .. TOTALLY overtoned (not just yr normal dark copies overtoned)

    did you ever get of the bottom of why? thx man!


  7. #7
    Senior Tech 100+ Posts MVPunisher's Avatar
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    Re: bizhub 751 spewing toner.

    Making sure the manual drum voltage is done with a multi meter helps and drum replacement. But sometimes it just doesn't accept the Dev change. Not sure why.


  8. #8
    RTFM!! 2,500+ Posts allan's Avatar
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    Re: bizhub 751 spewing toner.

    They do work. If these machines work hard. You can get 200K + from a developer.

    Its the bais connection that goes bad. Its a bearing.

    You can test for this by measuring conductivity between the metal pin on the side and on the mag roller.
    There needs to be developed in the tank with a full brush to test this. The resistance should be less than 80Ω.
    Otherwise you can modify a piece of spring wire to run against the shaft instead of the circlip. Tug the other end underneath the plate by loosening the screws and clamping it against the plastic. You will get rust from the shaft in a PM cycle or to.

    Go thru all the soft switches and set them back to default because that works. Like mentioned dont mess with the mag roller angle. you can adjust it. The tank only does about 900K before the leaking developer chows up a gear on the side.

    And if you are using 3de party toner change to original or good stuff. Sounds like toner starting with K.


  9. #9
    Step aside, noob 1,000+ Posts EarthKmTech's Avatar
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    Re: bizhub 751 spewing toner.

    I recently discovered a machine that the customer ignored the PM notification and had never had a single call.

    it had 550K on the clock and was still running the original developer and the machine was clean inside.

    I went there because of an unrelated matter.

    It got the Full PM as per the book and now like every other machine its dumping every 100K. Cant win.

    If at first you don't succeed, try the way I told you how to do it in the first place.

  10. #10
    Field Supervisor 500+ Posts
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    Re: bizhub 751 spewing toner.

    I actually have the opposite issue with undertoning...its also burning up the corona wires on the TS assembly very quickly....going to be performing a drum/pm/dev replacement when the PM kit comes in...and yes, I followed the ~10 service mode operations.

    To eliminate bias shortage:
    FullSizeRender.jpg

    Change dipswitch 23-2 and 23-3 from 0 to 1.This decreases toner density by 1.5%.


    I thought there was another bulletin about overtoning, but I don't see one; however, the OP might be talking about this known issue:

    Solution ID Solution Usage TAUS0900529EN*
    Description
    The copier outputs gray background after performing the maintenance on the copier.
    Solution
    Cause: This issue is caused by defection of the image density control in the beginning of the PM Cycle.

    Solution: This issue has been addressed with a firmware updated to the following versions:

    bizhub 751: Printer controller program (combined) version.32 and above
    bizhub 601: Printer controller program (combined) version.32 and above

    After completing the update, please be sure to perform the following.

    1. Check the DIPSW10-3 is 1.
    2. Replace the Drum and the Developer to the new one.
    3. Reset the fixed parts counter of the Drum and the Developer to 0.
    4. Execute the Maximum density adjustment.


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