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  1. #1
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    Can anyone explain the copier process like what type of charge is genrated

    Helo

    Can somone explain me the copier process like what type of charge (positive or negative charge) is generated by corona and what charge is on drum and toner so it attracts each other.
    I want to know when would black dots appear from where the drum sparks and where white dots come.

  2. #2
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    Can anyone explain the copier process like what type of charge is genrated

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    Re: Can anyone explain the copier process like what type of charge is genrated

    Quote Originally Posted by Sahil102 View Post
    Helo

    Can somone explain me the copier process like what type of charge (positive or negative charge) is generated by corona and what charge is on drum and toner so it attracts each other.
    I want to know when would black dots appear from where the drum sparks and where white dots come.
    Stop posting this problem multiple times

    Sent from my SM-G960U using Tapatalk

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    Re: Can anyone explain the copier process like what type of charge is genrated

    Do you have a test you need to take ?

    My friend Canon manuals explains everything in details for you .

    But u need to know that not all printers work with the same technology.




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  4. #4
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    Can anyone explain the copier process like what type of charge is genrated


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    Re: Can anyone explain the copier process like what type of charge is genrated

    In section 2 technology of the Canon 8500 series service manual this is explained. The laser writes to the non image areas of a positively charged drum . We would describe that as "Write to white".

    If the drum is chipped that machine should represent the chip as a white mark. Maybe someone could test this to verify. It is a good question.

    Many other machines write to black so a chipped drum surface would tend to produce black marks.

    Canon 8500 series white writer.pdf

    I don't think it is 100 percent predictable whether drum surface chips will show as black or white regardless of polarity
    Last edited by nathicana; 4 Weeks Ago at 06:19 PM.

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    Field Engineer 50+ Posts fchu5959's Avatar
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    Re: Can anyone explain the copier process like what type of charge is genrated

    Quote Originally Posted by Sahil102 View Post
    Helo

    Can someone explain me the copier process like what type of charge (positive or negative charge) is generated by corona and what charge is on drum and toner so it attracts each other.
    I want to know when would black dots appear from where the drum sparks and where white dots come.

    This is ,in fact, a very good question that most of the Canon trainers skip to answer nowadays because most of them have not got the proper training to explain that.
    Yes,Hishamawada is right to say that evrything is explained in the manuals but it is not easy to understand.
    It is all a matter of positive and negative charges or attraction and repulsion between like and unlike charges and if the laser "writes" or "erase"(that's the way i learned it from Canon France training camp 25 years back)
    So,of course,you can predict the result of a chip on the drum.
    To make it simple,if the drum is Amorphous Silicon(which is the case on high speed black and white models),the result will be a white dot.But since you do not have white toner,the white here is the color of the paper.if you want to check it,make a full page black on a yellow paper,the color of the dot will be yellow.In other words,the chip on the drum will not attract toner.
    On the other hand,if the drum is OPC(Organic photoconductor),the chip on the drum will result in a black or color dot(on color copiers).

    Always remember that,Amorphous silicon drum is charged positively by the corona grid and the laser writes on non image area whereas the OPC drum is negatively charged by the corona grid or primary roller and the laser writes on image areas.

    It's always interesting to know and understand the theoretical fundamentals of Xerography but even without that knowledge,you could be a smart tech with experience and common sense.




  6. #6
    Service Manager 5,000+ Posts
    Can anyone explain the copier process like what type of charge is genrated

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    Re: Can anyone explain the copier process like what type of charge is genrated

    Quote Originally Posted by fchu5959 View Post
    This is ,in fact, a very good question that most of the Canon trainers skip to answer nowadays because most of them have not got the proper training to explain that.
    Yes,Hishamawada is right to say that evrything is explained in the manuals but it is not easy to understand.
    It is all a matter of positive and negative charges or attraction and repulsion between like and unlike charges and if the laser "writes" or "erase"(that's the way i learned it from Canon France training camp 25 years back)
    So,of course,you can predict the result of a chip on the drum.
    To make it simple,if the drum is Amorphous Silicon(which is the case on high speed black and white models),the result will be a white dot.But since you do not have white toner,the white here is the color of the paper.if you want to check it,make a full page black on a yellow paper,the color of the dot will be yellow.In other words,the chip on the drum will not attract toner.
    On the other hand,if the drum is OPC(Organic photoconductor),the chip on the drum will result in a black or color dot(on color copiers).

    Always remember that,Amorphous silicon drum is charged positively by the corona grid and the laser writes on non image area whereas the OPC drum is negatively charged by the corona grid or primary roller and the laser writes on image areas.

    It's always interesting to know and understand the theoretical fundamentals of Xerography but even without that knowledge,you could be a smart tech with experience and common sense.




    Very good. Too many people fail to learn what I consider to be foundational knowledge. A house can't stand if it doesn't have a strong foundation.
    Embrace the process, not the outcome.

  7. #7
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    Can anyone explain the copier process like what type of charge is genrated


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    Re: Can anyone explain the copier process like what type of charge is genrated

    Quote Originally Posted by fchu5959 View Post
    This is ,in fact, a very good question that most of the Canon trainers skip to answer nowadays because most of them have not got the proper training to explain that.
    Yes,Hishamawada is right to say that evrything is explained in the manuals but it is not easy to understand.
    It is all a matter of positive and negative charges or attraction and repulsion between like and unlike charges and if the laser "writes" or "erase"(that's the way i learned it from Canon France training camp 25 years back)
    So,of course,you can predict the result of a chip on the drum.
    To make it simple,if the drum is Amorphous Silicon(which is the case on high speed black and white models),the result will be a white dot.But since you do not have white toner,the white here is the color of the paper.if you want to check it,make a full page black on a yellow paper,the color of the dot will be yellow.In other words,the chip on the drum will not attract toner.
    On the other hand,if the drum is OPC(Organic photoconductor),the chip on the drum will result in a black or color dot(on color copiers).

    Always remember that,Amorphous silicon drum is charged positively by the corona grid and the laser writes on non image area whereas the OPC drum is negatively charged by the corona grid or primary roller and the laser writes on image areas.

    It's always interesting to know and understand the theoretical fundamentals of Xerography but even without that knowledge,you could be a smart tech with experience and common sense.



    What you say may be true of Canons and I realize this is a Canon thread. Most of what you wrote is not a rule though.

    OPC drums are not always negatively charged as you can read on this page from the Kyocera M2535dn service manual.

    OPC positive charged.pdf

    Drum chips can show as image or non image depending on circumstances. This is shown on these two prints from the very same machine, an M2535dn.

    Black and White marks.pdf

    Though it may be uncommon plenty of machines have written to the image areas of Amorphous Silicon drums, why wouldn't they be able to? An example would be the Kyocera 820.
    Last edited by nathicana; 4 Weeks Ago at 01:28 AM.

  8. #8
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    Can anyone explain the copier process like what type of charge is genrated


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    Re: Can anyone explain the copier process like what type of charge is genrated

    Quote Originally Posted by BillyCarpenter View Post
    Very good. Too many people fail to learn what I consider to be foundational knowledge. A house can't stand if it doesn't have a strong foundation.
    I can never seem to remember what charge is on the drum or if you block the slit glass will it be white or black on the paper. I don't think remembering all of that is necessary to service MFP's these days. Day to day problems are pretty straightforward and when I do run into a difficult problem, I can just look it up at that time. There are just too many variables to try to remember.

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    Senior Tech 100+ Posts ReproKev's Avatar
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    Re: Can anyone explain the copier process like what type of charge is genrated

    You can also get black "pepper spots" across the page (looks like someone sprinkled pepper on the paper) on those same Canon high speed copiers with the ASI duums. That comes from not replacing the primary charge wires. If you let it go long enough, the primary corona will arc to the drum, permanently damaging the ASI surface and causing the white spots in the black image areas.

  10. #10
    Service Manager 5,000+ Posts
    Can anyone explain the copier process like what type of charge is genrated

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    Re: Can anyone explain the copier process like what type of charge is genrated

    Quote Originally Posted by Sahil102 View Post
    Helo

    Can somone explain me the copier process like what type of charge (positive or negative charge) is generated by corona and what charge is on drum and toner so it attracts each other.
    I want to know when would black dots appear from where the drum sparks and where white dots come.

    Read the service manual for your unknown machine
    Let us eat, drink, and be merry, because tomorrow we may die!

    For all your firmware & service manual needs please visit us at:

    www.copierfirmware.co.uk - www.printerfirmware.co.uk




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