km c450 no color

[chriscctx]

konica minolta c450 is only printing in black, no color. Came on suddenly. All color tests will just print black. All color printing ceased at the same time.

Any ideas?

[jamesmutz]

When you say printing black on the colour test print, do you mean it is only the black portion of the print that is printing or that it is printing the entire test print in black? It could be the transfer pressure/retraction as the black IU is always in contact with the belt but the colours only engage when needed. As a basic step, these machines seem to do strange things occasionally when it comes to colour but a good turn off/on usually fixes them.

[JustManuals]

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[chriscctx]

Just the black prints

It's only printing the black portion of the test. I have several color tests I run some of which are files of my own. When they are ran, only the black areas of the tests are printed - the other areas that are to be in color do not print.

The reason I find this strange is that is was working fine according to the printed copies I saw just hours before.

[bizhub1]

I would check transfer belt assy, see if the color rollers are moving properly

[ddude]

I would check transfer belt assy, see if the color rollers are moving properly

Agree- I think that the transfer belt moves up against the color IUs when a color copy is requested, it would appear that your transfer belt is not contacting the color IUs

[chriscctx]

And that would happen all at once with all three CMY iu's?

[ddude]

Yes, because I believe that the CMYs are working, the belt just isn't contacting them. iirc, the belt is always set for black, but needs to come up to position for any (and all) color copying.

[chriscctx]

replaced the transfer belt - no change

[chriscctx]

p6 p7 p8

I am getting a p6, p7 and p8 error code - which are cmy imaging unit failures but can not find out why

[minimerlin]

I am getting a p6, p7 and p8 error code - which are cmy imaging unit failures but can not find out why

Because the IDC sensors do not see anything on the transfer belt...because it is not getting primary transfer from the IUs!

Take out the belt and make sure that the rollers move correctly when you operate the cam gear.

[kan]

Have you tried half tone test pattern (set to 100) for each of the color in test mode? If you have not, test 8.5 X 11 paper (landscape) and see if the paper is completely blank or you do see some traces of color you are testing. Check for all CMY
Next remove the image unit and look from the top (drum side up) and look for the mag roller through the myler and see if there is any starter brush on the roller.

[chriscctx]

The only thing that prints is black - all color tests produce blank white pages. To recap - the transfer belt has been changed with no difference. I think its safe to safe its not the transfer belt. This situation came on suddenly, it was not a problem that got worse over time. Could it be a bad motor? (Just thinking outside the box). Imaging units appear to be good and have even swapped a few of them out with no difference.

[bizhub1]

Not by a manual now but see if you can turn on the retaction motor in service mode, it sure sounds like the color rollers in the belt are not moving towards drums

[chriscctx]

how do I turn it on from service mode?