We're having a problem with one of our HP 8100 and one of our 8150 printers. When printing anything longer than 11" there is a distortion in the print near the bottom of the page. It happens every few pages on one of our 8150 printers and every page on one of our 8100 printers. It's difficult to describe, so I'm posting a link to an image of the problem:
We do frequent, high quantity laser jobs on 8.5 x 15 paper for one of our clients and this has effectly knocked out two of our printers for these jobs. Any help would be greatly appreciated.
Thanks,
Don
Re: HP 81xx Quality Problem by dmzcompute (7/21/08 4:54 PM) reply
The only things that cause this would be the paper pickup units or the registration assembly. Does it happens from all trays or better yet what trays are you using to send the jobs? I guses it would also be possible for the feed unit behind the transfer roller or even the transfer roller to be the culprit but that would be rare.
Re: HP 81xx Quality Problem by bullshop (7/22/08 7:09 AM) reply
Stop the feed with the main power switch before it gets to the fuser.(kind of a modified half test)You must stop the error after the cartridge/trans roller but before its fused. Could be as the image is formed,possible trans roller white bushings or even the fuser??? Try it. Thanks (wild guess????) Geo
Thanks for the responses. We're printing from tray 3. I tried powering down before the sheet got to the fuser and the problem is still there - so it's happening before fusing. It does not happen from all trays, but there are issues with other trays - light print, etc.
We sent both printers out to be repaired and were told that only 1 was able to be repaired. When we got them back, both were still bad. Is it really possible that a repair shop couldn't figure out this problem?
Re: HP 81xx Quality Problem by dmzcompute (7/22/08 4:33 PM) reply
I still think the registration assembly is the most likely candidate with a small possiblitily of the feed plate. I really have discounted the feeding from the tray since it would appear where it is happening is after the paper has left those feed items. Since the registration assembly feeds the paper to the toner cartridge drum and controls it at this point if it sort of hangs for a second you will get what you are getting. Your defect occurs when the paper does not move evenly thru the unit and sort of stops or slows down for a minute period and then resumes correct speed.
Okay, I've replaced the registration assembly with one taken from a spare printer. In the process, I broke the clutch cover and had to replace it. D'oh!
The problem persists, even with the new registration assembly. What is the feed plate? I can't find that in my service manual.
Thanks!
Re: HP 81xx Quality Problem by dmzcompute (7/23/08 4:06 PM) reply
The feed plate is the metal and black plastic piece which sits behind the transfer roller and in fact the transfer roller locks into it. Very difficult to remove and keep intact so be careful if you are going to try and swap with another unit. You may want to move the transfer roller and bar from another printer to this one before you do the feed plate just in case it is causing the issue.
Re: HP 81xx Quality Problem by MMurray (7/23/08 7:08 PM) reply
Given where on the page the problem is happening,I would suspect that the problem is fuser related.To check,first remove the fuser and carefully inspect the area inside the printer where the paper enters the fuser.Make sure that there is nothing that could even momentarily catch the paper as it goes by.While your in there, also look at the gears that drive the fuser and make sure that they are in good shape.Lastly, try a fuser from a known good printer.
Re: HP 81xx Quality Problem by dmzcompute (7/23/08 8:01 PM) reply
Don, after looking at your image the print is being compressed I would check for a burr on any of the paper guides. the paper input unit or the timing section has caused hesitation problems before for us but never mechanical blurrs as you are showing.
Please post your findings- we work on quite a few of these 8100 series.BTW what type of paper are you printing on?
Re: HP 81xx Quality Problem by Rob S (7/24/08 2:30 PM) reply
I did not see where the toner cartridge has been changed. If it has please forgive me. In the past I have seen the drum gears in the cartridges become un-glued from the drum and give this sort of printout. Since most everything has been tried why not the cartridge?
Rob S
Re: HP 81xx Quality Problem by noras (7/25/08 2:35 PM) reply
Does it occure as well if you print a single page as well? Does it only happen if you print out of tray 3? If it only happens while printing bigger jobs, it is quite likely, that the troubblemaker is the vertical feeding assy - the part, that connects the additional 3rd tray with the printer. If this assy it too used you can hear that the motor inside of it hangs every couple of seconds. Wich causes a paperdelay at the sensors, they would slow down or stop the printer for a short time, wich could be reason for that blurrs.
Re: HP 81xx Quality Problem by MMurray (7/25/08 7:40 PM) reply
DMZ, I have read many of your posts and I agree that you are a fine tech.However,I have been working on copiers and printer for more than twenty years and I think I know something too.Yes, I read the fourth post.If you read my reply you noticed that I had him look at the paper path just before the fuser.I also had him check the fuser input guide by changing the fuser.Now,I think that we both can agree that what is happening is that the paper is hesitating at the point where the defect on the paper is directly under the drum in the toner cartridge.Now, if he puts the paper down in the printer with the defect directly above the transfer roller, then I believe that the lead edge of the paper will be very close to the area where that hesitation is being caused. In my experience that will probably be just about where the paper leaves the transport belts and first touches the entry guide of the fuser.That is why I had him looking in that area.
Re: HP 81xx Quality Problem by dmzcompute (7/25/08 8:39 PM) reply
Good point. What I find interesting is the user may have mislead us. In the 4th post he says "I tried powering down before the sheet got to the fuser and the problem is still there - so it's happening before fusing." Well if the sheet has not reached the fuser there is no way that the defect can be at the bottom of a sheet that is longer than 11" since there is only about 6 inches from the toner drum to the fuser entry. In fact it is not only possible the fuser could be causing the issue, but it could also be the facedown assembly. I would have him have the paper come out the faceup output on the left side just to see if the defect stops. If it does the facedown assembly is the issue and if it sitll has the defect then as you pointed out the fuser could be an issue. The only reason I discounted the fuser was the 4th post, so good catch on your part.
Thanks for all your suggestions. To sum up, I changed the pickup and feed rollers for tray 3. I swapped the toner cartridge and the fuser. I changed the feed plate and registration assembly. None of these fixed the problem. It turned out to be something so simple that I (not to mention to the repair shop that had it for a month) should have figured it out sooner . The top of one of the springs that give tension to the transfer roller had come off and been bent to one side. Once we removed the spring and reseated it properly, the problem disappeared. Here's a photo of the spring, properly seated:
Generally when that spring falls down or comes out you get streaking printing on the top of the page and it usually occurs with all pages no matter what size. Live and learn. What is interesting is if you had replaced the feeder as I suggested it would have solved the problem since that part is part of the feeder assembly.
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