3051 Ci poor CQ , light output

[Geo]

Hi All

Have a 3051Ci with 137 K on color and 240 K on B.W.
All colors except M are fading in the rear in varying degrees. Half tones look good ,but the solids fade toward the rear. The black color belt sample was done with the charger removed from the black drum unit. The faded pattern is what I am getting on the solids but not to that extent.

I tried the following without any improvement..
Ran the standard M.M. and DV refresh without any improvement M.M. 410 and 412 error out
Transfer belt
Charger Rollers
Drum assy.
Reseated H.V PCB
Cleaned and checked all the grounds.
Cleaned laser assy.

What's bugging me is that chargers on K,C and yellow develop a whitish coating with in 400 copies, bet the M stays clean. AND swapping the K drum with M does not change the image ( M still is good and K still is bad.)

Any thoughts

Thanks

[wragsdale]

Looks like developer bias. I would suggest replacing the affected developer units.

[blackcat4866]

Looks like developer bias. I would suggest replacing the affected developer units.

Yup. Black developing unit will resolve this. I've seen it before. =^..^=

[Geo]

Hi All

I thought about the DV units...but three failing at the same time with the exact same symptoms ? This just seems unlikely , unless something else is happening. Blackcat ..are you saying that a bad K Dv unit will affect yellow and cyan?

Thanks
Geo

[darry1322]

I had this same symptom on a 3051Ci. Cyan was the worst. After changing the cyan unit all others cleared as well.

[blackcat4866]

Hi All

I thought about the DV units...but three failing at the same time with the exact same symptoms ? This just seems unlikely , unless something else is happening. Blackcat ..are you saying that a bad K Dv unit will affect yellow and cyan?

Thanks
Geo

The U089 Sample set can remain entirely unaffected by this problem. It goes entirely unnoticed in fill rates below, say 65%. In fill rates above 65% it gets very noticeable. Your internal test pattern is mostly 20% fill of each color and a very narrow band of 80% fill between.

Depending on the colors present in your test pattern (especially the second page of your sample), you can see that CMY are entirely present, and only the black component is missing from those 80% fill areas.

AlphardII black developing1.JPGAlphardII black developing2.jpgAlphardII black developing3.JPG

In situations like this, this test pattern is very helpful:

Yes it's just the black. And I'm glad that you're looking and thinking. When you print off the attached test pattern it will only affect blocks above 65% fill and at the interval. =^..^=

[copier parts n.ireland]

ive replaced on average 2 develeper units per copier thankfully covered under warranty on about a dozen utax 3005ci/3050ci copiers now,always seems to be magenta and cyan units,our service department is still looking into problem and have been told to start installing cassette heater elements.