KeepItPrinting.com

[RCBlue]

Hi all,

I have a KIP 9900 in our office (Approx 2 Mil/Sq/ft) that repeats the image on the outer 5 inches on both sides of the print. (36" roll"). The image repeats itself approx 22 inches, so I'm pretty confident that it's a drum cleaning issue. (Using OEM Toner)

Print quality is great, with good line quality and solid area fill. Maybe too good solid area fill because it is those areas, with large solid area fill, that causes the repeating image. (i.e. Title block, logos, large bold text, etc.)

Luckily, we have a second 9900 in our office, so I was able to swap parts from a known good machine. I swapped the Drum, Cleaning Roller, Charge Unit, Developer Unit, Eraser Lamps, T/S Unit and Pre-transfer Lamps. None fixed the problem.

I checked:

1. HVP1 (Image Corona)
2. HVP3 (Transfer Corona)
3. HVP4 (Separation Corona DC)
4. HVP5 (Cleaning Roller)
5. HVP6 (Grid Plate of Image Corona)

All checked good

I did find a problem with the Developer Bias voltages however.

Print Cycle:
Developer Bias measured -131.6V vs the book's value of -200V
Toner Supply roller measured -101V vs -250V
Regulation Roller (Center) measured -200V vs -100V
Regulation Roller (Side) measured +101V vs +200V

Collection Process:
Developer Roller Measured +450V vs the book's value of +350V
Toner Supply measured -102V vs -340V
Regulation Roller (Center) measured -120V vs -20V
Regulation Roller (Side) measured +23.2V vs +120V

The voltages are way off spec, but copy quality is really good and the voltages are in line with the Developer voltages measured on the known good machine. So I'm reluctant to adjust any of the voltages. The Auto Density control was off on the good machine, so I turned it off on the bad machine as well, but didn't help.

I also reseated all the connectors and checked the wiring for the Developer Bias and Drum cleaning roller, and also checked drum ground. All good.

Reading through the print process in chapter 3, the note on page 3-6 states that the Developer unit cleans the remaining toner from solid black images that the Cleaning Roller was unable to remove. Sounds like it's probably the Developer unit, but I swapped it with a known good one, and it still repeats image. (The swapped developer unit, from the bad machine, works on the good machine)

Any Ideas?

[jedi4342]

And this is where the HP Pagewide is great. No repeated images. And no multiple areas to track down. Try putting voltages to specs. Was the spare drum you put in it, did it to have a lot of footage on it? I have put a new 1 in before and taken care of it. 1st thing is, put the voltages to where they are suppose to be. Maybe play with the height adjustment on the transfer corona.

[RCBlue]

Thanks for the reply,

I was able to get rid of the repeating image by lowering the Developer Bias to -90V. It's not the fix I would have liked, but line quality, solid area and half tones all look really good. I hate to take voltages off spec, but quality looks good so I'll see how it goes.

Yes both drums are fairly old (2.1M and 2.5M). Both are the machine's original drums. I only service these 2 9900s so I don't have a lot of experience to know what to look for in a drum that is reaching the end of its life. Is repeating image a symptom of a drum reaching the end of its life?

I really don't understand how the voltages can be so far off spec and still make good print quality. Both machines have approximately the same bias voltages and print quality is great on both machines. I haven't adjusted these voltages before, so these are the voltage adjustments that came with the machines new from the factory.

Could the values listed in my service manual be wrong? I have version A.0 of the service manual.

I'm pretty sure I'm making the voltages measurements correctly. Pretty easy measurements to make. I turned off the Auto Density Control before taking the measurements, like the manual says. The multimeter also checks good.

[jedi4342]

The drum will get a build up on it over time. I use to use d-ink to clean the drum and developer rollers. They have since then stop making d-ink as far as I know. Might be something else that works, I'm not sure. Someone else that is still working on these might know of something. Worth finding out and trying 1st. Drums are not cheap. I really like these HP Pagewide XL 8000's. Best production machine I have ever seen, so far. Service has been next to nothing. One has almost 3 mil. on it and the other has close to 2 mil on it. I do hope it does work out for you.