konica press c1085 has color issue

[Shawn]

our c1085 have severe color shift issue. I attached some pictures. it happens after couple hundreds prints, sometime only few sheets.
the color of the previous page is good, but the following page is suddently changed.
we changed all drums,charging units, developers.but doesn't help.so frustrate

any suggestion will be welcome.

thanks

Shawn

 

[Biggs]

Make sure your press environment is stable as it can be. In regards to temperature and humidity. If you calibrated before the run at 72 degrees and 36% humidity and an hour into the run it’s now 80 degrees and 48% humidity, your calibration set is no longer valid. Density will change and color will vary.

Also KMs in-line density check doesn’t check a large patch set. If I remember correctly it almost completely ignores the highlights and the lower end midtones. It could be the device is missing the color shifts. Or if you’re noticing shifts in heavier density areas, it may not be functioning properly.

also the machines power supply could be failing to regulate the primary charge voltage.

 

[Shawn]

Thank you Biggs.when we move our machine to new location,the power source has problem. It damage power supply inside the machine and the machine shows the error code. One technician come in and replaced the power supply board and fix the error code problem.since that,this color issue happened.

Could you please tell me which parts should I check?
Your information is very helpful I think

Thanks

 

[Shawn]

if color changing because of humidity and temperature, it should be changing slowing and won't be change suddently. is it right? as the second picture shows, it became bluish suddently.

 

[Biggs]

I’m liable to agree with you on that one. Environmental change is often a gradual one.

let me ask this, does it seemingly happen after precisely the same amount of sheets? Or do you notice it occurs immediately after the machine pauses during the run, possibly to run it’s auto adjust feature?

 

[Shawn]

It's randomly happened. Sometimes 500 hundred, sometimes a few sheets. Whatever it's continues running or pause and run.
Once it happen,it stay like that.doing manual adjustment doesn't help. Calibration will help but only for very short time.after couple sheets,it happen again.

 

[Biggs]

Your top sample seems like a rather normal flux in color. The bottom sample photo is troubling. It’s almost like you’re completely losing an imaging station. Like magenta has simply disengaged.

if you have time, set up a test sheet. Divide an 11x17 or 12x18 sheet into quarters. Fill each quadrant with patches of halftones, one quarter with 10% and 30% cyan patches, then magenta in the next quadrant and so on. See if you can run the file until the color change occurs. Hopefully without wasting too sheets and clicks. I’m curious to see if the issue resides exclusively in one station.

 

[Shawn]

Will do it next week and let you know.

Thanks

 

[Shawn]

Hi,Biggs
After running 100copies,it happen again. I measure by i1profiler, ymk only changed very small amount,but cyan has big change.
Any idea?

Thanks

 

[Shawn]

 

[Biggs]

At least it may seem we’ve isolated the problem to a single imaging station. Something is causing a flux in Cyans primary charge voltage. It could be the power supply to the primary charger, or possibly the charger unit itself. It could even be the developer power supply or station.

when you serviced the charger and developer did you replace the whole unit? Or just do the usual maintenance, wire, grid, and developer purge and replace.

if you replaced the entire units, I would look into what supplies or regulates the power to it.

 

[Shawn]

I didn't replace developer unit,only developer. I will try it once I get new developer unit. thanks

 

[Shawn]

Hi,Biggs
developer unit didn't come so far, but I think I found something new. I did sensor check---drum surface potential, I got all potential voltage at 500-600v. after that, I run a 100sheets test, when problem happen(more blue),I stop the machine and check the drum surface potential again, cyan potential voltage became 360v. I run the charge potential auto adj, the number get normal(around 500v), run job again, stop and check the drum voltage again, it became 700v. which means cyan drum potential change back and forth frequestly.

I exchange cyan and magenta drum potential sensor and pwb, doesn't help.
any suggestion?
thanks

 

[Biggs]

It would seem the sensor is functioning properly. I may have to do further research and get back to you.

 

[Shawn]

Yeah. Digging deeper and deeper. Hope we can fix it together.thanks

 

[Shawn]

Hi,Biggs
Machine was fixed.its hvps1 damaged. After replacement,working fine.thanks for your help.