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  1. #1
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    308 - Fully black prints

    Hello guys! Somewhat stumped, and curious if anyone has seen something similar before

    Customer called about their 308 with 48k meter (bought 2017) printing pure black. I get there with a PH and my font list is pure black. No codes, but possible P9. Swapped out the laser. First print is perfect, but quickly darkened into a pure black sheet after 10 pages.
    Questioned the customer again and he mentioned when he lets it sit for a while it gets better for a couple pages. Saw the P9 and a TCR of 0.5%, toner was empty. Manual add toner from their empty bottle, got TCR to 6.5%. One page later it dropped to 4%. Put brand new toner in, started auto adding toner, after a couple minutes of adding it gave a toner empty screen. Opened and closed the front door and it continued adding. Repeated that add/empty three times. During all this TCR was rapidly fluctuating between 2% and 4%.
    I have a new developer coming in this week, but I've never seen developer backgrounds get to a pure black, its usually a light gray that doesn't change regardless of how many pages printed. Any other ideas?
    Last edited by tmmdmmm; 06-13-2021 at 12:40 AM.

  2. #2
    Master Of The Obvious 10,000+ Posts
    308 - Fully black prints

    blackcat4866's Avatar
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    Re: 308 - Fully black prints

    I think the toner density issues you have documented are exactly what you might expect when printing 100% fill black images. So I think you've focused on a consequence, not a cause.

    You did not mention that there were no page voids. If there were voids I would suspect laser or image processing ... but I suspect that there were no image voids, meaning that you're probably losing primary charge. Maybe at the contacts, maybe a primary charge short, maybe HVT.

    Were it me, I'd start with a drum unit, check charge contacts, then HVT. =^..^=
    If you'd like a serious answer to your request:
    1) demonstrate that you've read the manual
    2) demonstrate that you made some attempt to fix it.
    3) if you're going to ask about jams include the jam code.
    4) if you're going to ask about an error code include the error code.
    5) You are the person onsite. Only you can make observations.

    blackcat: Master Of The Obvious =^..^=

  3. #3
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    Re: 308 - Fully black prints

    Quote Originally Posted by blackcat4866 View Post
    I think the toner density issues you have documented are exactly what you might expect when printing 100% fill black images. So I think you've focused on a consequence, not a cause.

    You did not mention that there were no page voids. If there were voids I would suspect laser or image processing ... but I suspect that there were no image voids, meaning that you're probably losing primary charge. Maybe at the contacts, maybe a primary charge short, maybe HVT.

    Were it me, I'd start with a drum unit, check charge contacts, then HVT. =^..^=
    Thanks, I did swap out the drum as a gamble before throwing the PH in. Wouldn't charge contacts/high voltage cause the opposite issue; Completely blank prints? And yeah, I'm sure the lack of toner and initial 0.5% TCR was a symptom of the original problem, but what's throwing me off is the rapid up and down of TCR while adding toner, w/out any prints

  4. #4
    Master Of The Obvious 10,000+ Posts
    308 - Fully black prints

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    Re: 308 - Fully black prints

    Quote Originally Posted by tmmdmmm View Post
    ... Wouldn't charge contacts/high voltage cause the opposite issue; Completely blank prints? And yeah, I'm sure the lack of toner and initial 0.5% TCR was a symptom of the original problem, but what's throwing me off is the rapid up and down of TCR while adding toner, w/out any prints
    Back in the analog days, yes, high voltage loss gave blank images. But at the advent of digital copiers, high voltage loss presents as black images and no voids. Digital copiers charge the drum negative, then laser discharge the image areas to become less negative. Confusing, I know.

    Did you say there are no voids? =^..^=
    If you'd like a serious answer to your request:
    1) demonstrate that you've read the manual
    2) demonstrate that you made some attempt to fix it.
    3) if you're going to ask about jams include the jam code.
    4) if you're going to ask about an error code include the error code.
    5) You are the person onsite. Only you can make observations.

    blackcat: Master Of The Obvious =^..^=

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    Re: 308 - Fully black prints

    Quote Originally Posted by blackcat4866 View Post
    Back in the analog days, yes, high voltage loss gave blank images. But at the advent of digital copiers, high voltage loss presents as black images and no voids. Digital copiers charge the drum negative, then laser discharge the image areas to become less negative. Confusing, I know.

    Did you say there are no voids? =^..^=
    Thanks for the clarification, I think I'm just basing it off poor movers knocking those contact assemblies out of position, causing blanks across one or more colors. From what I can tell, no voids, its a pretty consistent gray that quickly turns black.

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    Re: 308 - Fully black prints

    Here’s a reference immediately after the PH change, Left I had laying around from a different machine
    7C5F8B59-444E-43EB-83D7-82A26E84860C.jpeg

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    Master Of The Obvious 10,000+ Posts
    308 - Fully black prints

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    Re: 308 - Fully black prints

    If it was overtoning you would have edge voids. Concentrate on charge. =^..^=
    If you'd like a serious answer to your request:
    1) demonstrate that you've read the manual
    2) demonstrate that you made some attempt to fix it.
    3) if you're going to ask about jams include the jam code.
    4) if you're going to ask about an error code include the error code.
    5) You are the person onsite. Only you can make observations.

    blackcat: Master Of The Obvious =^..^=

  8. #8
    Service Manager 2,500+ Posts tsbservice's Avatar
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    Re: 308 - Fully black prints

    What are voltages readings in Table number? I mean Vdc and Vg. Inspect closer developer and drum contacts machine side. If possible swap developer unit for a test.
    Good luck.
    A tree is known by its fruit, a man by his deeds. A good deed is never lost, he who sows courtesy, reaps friendship, and he who plants kindness gathers love.

    Blessed are they who can laugh at themselves, for they shall never cease to be amused.

  9. #9
    Senior Tech 100+ Posts Zesti's Avatar
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    Re: 308 - Fully black prints

    Quote Originally Posted by blackcat4866 View Post
    If it was overtoning you would have edge voids. Concentrate on charge. =^..^=
    Not showing void edges clearly shows PH unit is fine... Check HVT...... A dumb question....do they have mice??????

  10. #10
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    Re: 308 - Fully black prints

    KMs "write to black". The drum is fully charged, anywhere the laser writes, the charge is dropped (255 steps). No charge would show up as 100% fill, including edge deletion areas. Could be the drum itself, the rear contacts or the HVT. The intermittent copies lead me to think it's a contact block..E

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