Ricoh C7100X - random dots printing in background/non-image area

Discussion in 'Ricoh Color Laser Printers & Color Copiers' started by Carl Boehm, Jun 15, 2019.

  1. Carl Boehm

    Carl Boehm New Member

    Joined:
    Jun 2019
    Messages:
    2
    Location:
    Renmark, South Australia
    G'day all... first time poster here and hoping someone may be able to help me out - I work for a small commercial printing company and we have a Ricoh C7100X production machine. We've had many issues with it over the past 2 and a half years and the local tech just doesn't seem to be able to fix it and Ricoh have been pretty useless in helping solve all the issues. Would never recommend anyone getting one for production work.

    One issue I'm having, and this current job (business cards) I'm trying to print has made it really noticeable, is a dot being printed in the background/non-image area. Under a glass these dots are a mix of CMYK dots, random sizes and spaces. It doesn't matter what I print they're there. I can print a completely blank page and it's covered in these dots up to the print margin. I've tried calibrating it numerous times and seems to help for a short while but doesn't completely get rid of them. I've also tried using other colour profiles with no difference. Executing DEMS also seems to help temporarily.

    This issue has been getting worse as the machine ages which leads me to believe it's a hardware issue. Going back over jobs we printed when the machine were first installed, the dots have always been there but were barely visible to the naked eye. Now they stand out and is quite obvious.

    I should also note it's much worse on heavier stocks (300gsm Pacesetter single sided gloss in this case). On thinner stocks, such as 90gsm laser it's barely noticeable. On 130gsm coated stocks such as HannoGloss/Sovereign it's quite noticeable.

    Anyway, if anyone has any experience or thoughts on this issue I would appreciate hearing from you. The techs at Ricoh haven't found a solution and I'm drawing a blank with google searches!

    Thanks in advance
    Carl
     

    Attached Files:

  2. Biggs

    Biggs Senior Member

    Joined:
    Mar 2017
    Messages:
    119
    Location:
    Edison, NJ
    It sounds like residual toner build up on the outskirts of the image transfer belt. Open the marking engine doors, remove the necessary plates to pull out the ITB, and take a look.
    You may find the outer rim of the ITB covered with toner. The cleaning station really only targets the belt's center, and the small cleaning pads intended to wipe toner become overwhelmed quickly.

    I don't actually see the dots in the attached picture. Are the dots within the printable area? or on the outer edge of the sheet?
    If the dots consist of all colors, the ITB is likely the culprit. The belt itself, the cleaning web, or in rare cases the transfer roller may need to be replaced.
    In the meantime you can try increasing the transfer voltage of the press to see if you can pull all of the toner off the belt, what could be happening is that 90% of the toner is pulled onto the sheet and some toner is left behind and transferred to the next sheet. The cleaning station usually accommodates residual toner like this, but if too much is present, or cleaning station itself is not functioning properly the toner will remain on the belt until the next sheet comes around.
     
  3. Carl Boehm

    Carl Boehm New Member

    Joined:
    Jun 2019
    Messages:
    2
    Location:
    Renmark, South Australia
    Thank you for the reply Biggs... The 'dots' (or probably better described as noise perhaps?) I'm referring to is in the white are of that attached image - it looks like a speckly background. Under a glass it's just a mass of random CMYK dots covering the entire print image area (not on the very outer edge outside of the print margin).

    Our machine is still under service contract so I leave it up to the local tech to go delving inside. I've had a hunch all along, and have told the tech numerous times that I think it's a software issue rather than hardware. He seems to think it is also an excess/residual toner issue. We've had problems in the past where the waste toner bottle replacement notification hasn't come up and resulted it a mess of toner building up in the engine. The notice still doesn't come up from time to time so I periodically check it now. But anyway, I came to work today to finish off a few other jobs and thought I'd give these business cards one more crack. I thought I'd try changing the paper catalogue/profile over to manual and set it to plain paper, paper weight 8 and ran a few prints off - the background dots were pretty much gone to the naked eye, although the toner was looking rather dull so swapped the catalogue/profile over to 350gsm Knight board (uncoated) and up'ed the fuser temp to 195°C and ran a few more prints and was still looking okay so ran the rest of the cards so I could get the job done.

    So this confirms my hunch it's something to do with the glossy output profile in the Fiery RIP. Even though yesterday I changed the output profile to the uncoated/plain within the job print settings, I still had the catalogue/paper profile set to the glossy coated stock I was using which may have overridden it.

    Thinking it through further, when I do the calibration with the EFI ES-2000 unit, I use Sovereign gloss stock which has a rather warm/bone/cream like hue to it, so perhaps the calibration device is registering the paper colour and tries to correct it by adding more background dot to make it appear whiter. Something to investigate further perhaps.

    Attached is a comparison of the background 'dots/noise' from yesterdays print on coated glossy setting, on the right is the print from today used uncoated setting.
     

    Attached Files:


  4. Biggs

    Biggs Senior Member

    Joined:
    Mar 2017
    Messages:
    119
    Location:
    Edison, NJ
    Ah, Now I see it. How could you miss it? It's pretty terrible to be honest, I had no idea.
    It's interesting that you went down the road of output profiles and calibration sets. Your machine is a bit older than mine, but Ricoh likes to incorporate white-points and simulate paper. Perhaps turning off the paper simulation, or switching your rendering intent to relative colorimetric instead of absolute colorimetric might help your image.

    Still, I must ask, when was the last time the ITB or transfer roller was serviced? If it's under contract, surely they looked there no? OR the vacuum system that moves waste toner into the waste container. It could be a hose that cracked or slipped off.
     
Loading...