C451 Bad color when print/copy, but self-test is perfect

[Jim Z]

Hi folks, new to this forum.

Have a Bizhub C451 that suddenly starting printing very poor color when copying or printing from computer.

The black copy/print is fine.

Going into Service Mode and doing test prints, colors print out and look absolutely great.

I've attached a good/bad sample print.

Someone please...kick me in the right direction!

Thanks! Jim in Daytona Beach

[copyman]

Re: C451 Bad color when print/copy, but self-test is perfect

Looks like something going on with Magenta image unit. What do the consumable lifes look like?

[Jim Z]

Re: C451 Bad color when print/copy, but self-test is perfect

Looks like something going on with Magenta image unit. What do the consumable lifes look like?

Consumables seem adequate.
Test print from service menu shows magenta not quite as prevalent as the yellow/cyan/black.
But certainly the colors in test print a lot better than the print sample first shown.

[Synthohol]

Re: C451 Bad color when print/copy, but self-test is perfect

My interpretation of the blurry sample is either a bad CCD or the mirrors are out of whack or dirty.
I don't remember if the 451 has the preview function but if it does just run a preview scan. If it looks like crap the issue is in the optics.

Process of elimination is your friend.

[tsbservice]

Re: C451 Bad color when print/copy, but self-test is perfect

My interpretation of the blurry sample is either a bad CCD or the mirrors are out of whack or dirty.
I don't remember if the 451 has the preview function but if it does just run a preview scan. If it looks like crap the issue is in the optics.

Process of elimination is your friend.

He said also printing from PC is bad so it has to be problem with print engine not the scanner.
Magenta and Yellow IUs may need replacement. IUs life counters may not be exactly accurate sometimes

[Synthohol]

Re: C451 Bad color when print/copy, but self-test is perfect

That's why that's why I suggested process of elimination if you could preview the scan or scan to a folder and it looks blurry your issue is the Optics especially when the machine is trying to calibrate itself and the Optics are screwed up so then print would be screwed up as well

[tsbservice]

Re: C451 Bad color when print/copy, but self-test is perfect

Hmmm, as author had some confusing initial statements I would guess any more. Just curious what's in oil can

[Jim Z]

Re: C451 Bad color when print/copy, but self-test is perfect

Hmmm, as author had some confusing initial statements I would guess any more. Just curious what's in oil can

If I was confusing in my original statements, let me know so I can clarify.

BTW, The scan function (to my email) results in a perfect copy.

Not sure why test prints from service menu would offer vibrant colors whereas copy jobs and print jobs are mostly missing the color.
In my thinking that eliminates toner, drums, belt, high voltage.

My experience with KM is very limited, but if this was an HP machine I'd say it needed a formatter board.

Thanks for all your input!
Jim

[tsbservice]

Re: C451 Bad color when print/copy, but self-test is perfect

Could you print full coverage pages at 30% fill, sepate for CMYK colors and post samples?
See attachment.

[Jim Z]

Re: C451 Bad color when print/copy, but self-test is perfect

Could you print full coverage pages at 30% fill, sepate for CMYK colors and post samples?
See attachment.

Half Tones are attached.
Thanks!

[tsbservice]

Re: C451 Bad color when print/copy, but self-test is perfect

Thanks for attachments. Something really strange happens here. Have to rethink.

[Synthohol]

Re: C451 Bad color when print/copy, but self-test is perfect

if its not mechanical it may be in image processing (PRCB)
its a 451 though, in sept 2017 that model reached end of life.
cant think of a better reason to upgrade. you dont want to marry a corpse do ya?
call a priest to give last rights and move on

[copyman]

Re: C451 Bad color when print/copy, but self-test is perfect

Agree with Syn on this being end of life. It is exactly why I have 2 working C451's trade-in's moving closer to dumpster everyday. I just don't have it in me to throw away perfectly good machines. Comes in handy if friends or family needing a quick 100 color prints for girl scouts, sports, etc. But eventually will need the room and throw them out working or not!

PM me if you end up wanting to keep the beast alive and need anything.

[Synaux]

Re: C451 Bad color when print/copy, but self-test is perfect

if its not mechanical it may be in image processing (PRCB)
its a 451 though, in sept 2017 that model reached end of life.
cant think of a better reason to upgrade. you dont want to marry a corpse do ya?
call a priest to give last rights and move on

I was leaning to the MFPB, but never seen seen such a thing so...

[Jim Z]

FIXED! C451 Bad color when print/copy, but self-test is perfect

I was leaning to the MFPB, but never seen seen such a thing so...

Thanks to all for your input.
I'm intrigued by what I believe are Gen X'rs and younger wanting to dumpster this fine machine.
I'm pushing 70 and have generally been successful with resurrecting 'hopeless' repairs.
I'm known locally as the 'Fix-It Guy', and perform miracles most every day.

Now for the cure:
I was fortunate to have a very skilled KM technician come by.
First thing he found was a Stabilization Failure when trying to do Graduation adjustments.
The half-tone printout only used about 1/4 of the page. See attached for before and after.
Turns out that dirty patch sensors were to blame. I guess these sensors are for Transfer Belt registration.
After a few passes doing Graduation adjustments, the old girl is back to being wonderful.
Thanks again!