full yellow background on color prints/copies

[Froota]

Hey,

I have a mx-2301 with full yellow background when printing/copy in color.
The transfer belt 1 and 2 and drum are full yellow when printing. We removed the shutter, replaced the mc pwb, and also replaced the gusa and dev. unit, but still no go.

When i'm doing a forced process control, i get fault 'K_hv_err', this while the problem is on the yellow unit. it's like the yellow drum is not been discharged but fulley loaded.
All other date is normal, and printing/copying in BK doesn't give a problem....

Any idea's?

[OMD-227]

Firstly, the reason you are getting the K_hv_err message is because the machine cannot read any black process control patches on the belt, due to it being fully covered in yellow. The MX2301 has 2 process control sensors, one for color, one for black, so if the belt is fully covered with toner (or damaged on some way) it will not be able to read the patches on the belt at the sensor location. You also know its not a black HV problem as all B/W pages are OK. Pretty much ignore that message as it will fix itself once you get the full yellow coverage problem fixed.

As for the solid color pages, if you have already replaced the drum unit, this problem on all MX color machines usually revolves around either the process electrode cover (upgraded twice) or the HV/MC board (also upgraded twice).
A poor quality/very used drum unit with deep scratches in the drum surface at the ends will cause this problem too due to constant charging. If your drum unit is OK, then its always one of the above causing this.
The process electrode cover has been upgraded twice to prevent a charge leak between the rear frame & the mc unit. You will also eventually get a F2-40, 41, 42, 43 code (depending on the color problem) as the machine cannot reach ready as the dev unit cannot adjust correct value.
The first modification to the process electrode cover (november 2008) was engraved with 'H1' on the plastic. The latest modification which also includes the MX2301 has 'H12' engraved on the plastic (August 2010). Check the machine serial number Froota. If it is made before August this year, order the new updated process electrode cover PFTAP0149FCZ2 (parts guide section 46, item 11).
This modification particularly helps in damp or cold environments. I can send you the bulletins on all this if you like.
I've done quite a few of these mods over the years and it definitely fixes the issue (if the drum didnt solve the problem to begin with). You need to take the main drive unit out first which is a pain if you haven't done many of them. Unfortunately the part is right in the middle of the machine.

Also, the MC HV board has been upgraded twice. Make sure you are using the RDENU0088FCP4 part number (usually printed on the board). If you have either RDENU0088FCPZ or FCP2, get it upgraded. If you are in a very high altitude, you can order RDENU0088FCP5 instead.

Either way, if the drum unit is good, your looking at either of these parts causing the problem. Put the shutter unit back in the machine, reseat the MC HV board, drum unit & dev unit, swap drum units around etc etc. If the problem is still there, my experience is always one of these parts (usually the process cover upgrade is the fix).

[Froota]

Hey Wazza,

I hoped to get a quick answer from you, without obligations.
We have a mx-2301 with a crashed body, so i can take part from that machine for swapping.
I will try something out, and give feedback.

thx in advance...

[Froota]

Hey,

Wazza, i had a good feeling about your explanation, reffering the process electrode cover, but unfortunately it did not resolve the problem.
We removed some parts from a (new) machine with a crashed body, and so i tried to resolve the problem by replacing some parts step by step.
I replaced the drive unit, pcu pwb, primary transfer pwb, gusa and development unit, and finally the process electrode cover.

I must say that it wasn't an electrode cover with the H12 mark, but with the H1. So your explanation still can be true, but we have to swap the machine with a replacement device, because the customer needs to print in color very urgent. It's a 3-months old machine, so there's still some warranty on it.

If we find a solution, i let you know..
I appreciate your help!

[jonezy999]

So did U put in a new Y drum init?

[OMD-227]

Thats what the 'gusa' is. The drum units for that series is MX27GUSA.


I hope you get an answer on this oneday Froota.

[jonezy999]

Thats what the 'gusa' is. The drum units for that series is MX27GUSA.

Well ya learn something new everyday. Time to log the brain off for the arvo, got my quota.

[sharphead]

Did you replace the developer after the drum was replaced I had the exact same problem only on black. Tried developer first then drum then process electrode cover then numerous boards eventually turned out if was the charge corona in the black drum unit. I had replaced but needed to put in new developer after, look at the simulation 25-1 to check the dev value

[Froota]

Did you replace the developer after the drum was replaced I had the exact same problem only on black. Tried developer first then drum then process electrode cover then numerous boards eventually turned out if was the charge corona in the black drum unit. I had replaced but needed to put in new developer after, look at the simulation 25-1 to check the dev value

I tried something out with another yellow development unit, en we swapped the drum unit with another color, but without result.
We also initialized the developer 1 time to see wich result we should get, and the TD sensor values were good. (except that they started much higher than the other colors)

Sharp advised us to also replace the laser unit, but i don't find the logic of it...

[OMD-227]

Really, really doubt you have a laser problem here Froota.

If you are sure your drum unit & dev are OK, change the most updated process electrode cover as I've said earlier, or change the HV/MC board. You have a charging problem, not a laser problem. You need to concentrate on items associated with charging.