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907tec
06-27-2012, 02:00 AM
I'm getting a little perplexed by this one, so I'm hoping one of you fine folks has seen this issue before:

16441

Basically, I have a Bizhub C650 (about 1.2 million clicks) with all yellow print out-of-registration. Part of the page is spot-on, the rest of the page gets increasingly further and further out of registration. As you can see from the registration pattern, the yellow is shifted differently across the page. Because of the varying amounts of registration-difference, skew adjustments and color-reg. adjustments are futile. This defect happens on all copies and prints, out of all trays, using all paper sizes, including on internal patterns. Constant P-21 codes, of course.

To make matters more complex, the machine is located on a ship that only comes into port once every 7-10 days. And, on top of that, technicians in other cities are occasionally servicing the machine without noting what service was performed. What I do know, because I have done it myself:

Tried (3) different yellow imaging units
Tried (2) different X'fer Belts
Cleaned all lasers (repeatedly)
Cleaned belt IDC sensors (repeatedly)
Replaced print head (x2, apparently techs in another city tried this again)
Replaced PWB-MFP
Replaced both Memory sticks


I have also tried lots of other crazy things, like putting shims on the yellow imaging unit to raise one side while installed in the machine. Updated all F/W, per the "p-21" tech bulletin. No difference. Before it is asked: yes, I did follow the setup procedures for the printhead (entering LD and skew values, lead/side edge adjust, skew adj. reset, etc.). Have also attempted all the steps in the "p-21" tech bulletin (entering low values for all skews, doing a whole bunch of init-stabs and skew adj. resets, updating f/w, all that).


....and YES, Paul, I do have a manual.

Shadow
06-27-2012, 02:12 AM
have you thought about swapping out the fuser unit?
I know it sounds off, but I have had the same issues with other Konica Minolta machines.
What happens is the belt in the fuser unit slips some and can cause that problem.
it will cause the paper to stall momentarily during the in-feed to the fuser.

lanierboy
06-27-2012, 11:40 AM
have you thought about swapping out the fuser unit?
I know it sounds off, but I have had the same issues with other Konica Minolta machines.
What happens is the belt in the fuser unit slips some and can cause that problem.
it will cause the paper to stall momentarily during the in-feed to the fuser.

I would recommend changing the fuser as i have also had issues on minolta machines where you have a mis-match in the paper speed between the fuser and transfer belt and this causes the shift, the image is ok at first due to it not being in the fuser yet.
also i would change any sensor arms in the timing or loop area as if these are worn it can cause the same thing

B0265
06-27-2012, 12:09 PM
Don't you get any P-22 codes? For me it looks like the problem is mainly in the main scan direction.

Albonline
06-27-2012, 08:01 PM
Don't you get any P-22 codes? For me it looks like the problem is mainly in the main scan direction.

Same here. would suspect the print head or connections to same.

907tec
06-27-2012, 09:47 PM
You guys are correct in that the issue is primarily in the main-scan direction. As I mentioned, the PH has been replaced twice already, as well as the transfer belt. The current transfer belt has 13k and the fusing unit has just under 20k (it had been changed by techs in another city, recently). To be honest, I don't really understand how the fuser could have anything to do with this issue. The shift is in the main scan direction and is only affecting one color. Whenever I have had issues with the loop sensor or fuser, it affected all colors at that point on the page.

The ship won't be back in town till Sunday, so I have been going through the Mgmt/Adj. Lists. I haven't given it a lot of time yet, but I did notice some funny things here:

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Look at the values for the IDC1/2 and Yellow Color Registration. IDC1 is at 0.20v and IDC2 is at 2.82v, with the sensor adjust values maxed out at 255. Also, the yellow registration values are through the roof with a difference of 2631 between front and rear. I am not entirely sure what to gather from this. I am kinda thinking about the good ole shotgun approach, replacing the ITB, IDC1, IDC2, and Yellow Iu at the same time.

Any other ideas before I bite the bullet?

minimerlin
06-27-2012, 11:23 PM
Swop the IDC sensors over to each others positions to see if the readings change...then fit 2 new ones!

Albonline
06-29-2012, 09:07 PM
you say its on a ship? what does the wall power look like? is it spikey?

907tec
06-29-2012, 09:34 PM
Yeah, all the wiring on these ships is horrible. Wall-power is definitely suspect. I had one C550 on a ship last year that got nuked by the flaky power, had to replace DC and AC power supplies on it. This one has been tried with a line-conditioner without any effect, so if the wall power is a problem, it has already damaged a board somewhere.

Chameleon
06-30-2012, 02:12 AM
This is out in left field but those PH units have a temperature control sensor and circuit, which can activate color reg+skew correction when it detects a change in temp. If there isn't away to increase that threshold in service mode or customer mode, maybe you can add some insulation for the sensor.

The only other suggestion I have would be to replace/check all the wiring going from the PH to the PH relay pcb or from the PH relay pcb to the MFP pcb.

tradewynnes2
07-13-2012, 09:29 PM
Try cleaning or replacing the 2 sensors under the fuser. They have to do with fuser speed, color registration and timing. I have seen various problems relating to these sensors.

Shadow
07-13-2012, 10:48 PM
I just took a closer look at the grid pattern and also noticed that the cyan is a little out of registration as well.
I also took a look at the printout and yes the yellow values are way out to lunch for what they should be.
have you tried to set them back to factory?
I think I know the machine that you are working on if you are located in Alaska.
I think I might have worked on it last summer when that ship was docked here in my area.
I would most likely bet that the printer control board took a voltage hit as well as the power supply unit.
another possibility might be in the gear drive for the colour units, the yellow drive might have a damaged or worn tooth.
just beat it with a big stick and keel haul the sob........................

JustManuals
07-13-2012, 10:49 PM
This Parts & Service Manual can now be purchased for $12.77 and downloaded immediately after payment from

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Paul@justmanuals.com

FrankieB
07-19-2012, 04:34 PM
Check the actuator inbetween the Transfer Belt and the fuser, on the frame, it does wear down/breaks and will give you color registration problems, there is a TB on this. if you need the part # let
me know!

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