CL7300 - Cyan problem

[Hyksos]

Our Ricoh CL7300 have a problem since a while, affecting only Cyan and only when printing light background, the cyan get lighter at the top of the sheet, here is an image:


We did replace drum and developer, that did not change a thing!

When we print 100% solid Cyan we don't have the problem, the color is the same from top to bottom, but as soon as we print light color that have cyan in it we get inconsistent color on the top 1/3 of the sheet

Anyone have any idea of the problem?

Thanks for the help

[E Winter]

Try cleaning the four laser protective glasses with a wet cloth (not with that thingy in the front door). If that doesn't help you might need to clean the polygon mirror motor. I've seen that issue a lot with the A3245 MFP series wich is using the same print engine.

[Herrmann]

my bet goes to the polygon mirror, it tends to get dirty at the edges, resulting in inconsistent prints of halftones. If you have really bad luck, the mirrors and glasses inside the laser unit needs cleaning also; if so, you are forced to remove the whole laser assy and open it to gain access to all parts.

[E Winter]

.....it's not that bad to do that on the printer compared to the MFP models based on that engine^^

[Hyksos]

I cleaned the protective glasses, no change

Then I decided to go for the polygon mirror.... man that's a pain to get there, I only opened the top of the laser unit and saw that it was perfectly clean inside, not a single dust, so I guess everything must be clean in there?

I decided to check the print output with a magnifier, the big difference is the size of the dots, there's no missing dot at the top of the page, they are only about half the size of the dot at the bottom ...

Dunno what to think, I should clean inside the laser unit?

[E Winter]

So you haven't cleaned the polygon mirror? It's not unusual that the laser unit looks fine inside but I bet that there is a slight bit of a dirt film on the mirrors edges like hermann said - even that is not always easy to see. IIRC there is no need to open the complete laser unit cause there is a metal cover above the polygon motor housing.

[Hyksos]

What do I need to clean on it? the slot in the middle or only the outside edge?

And why the problem is only with the Cyan? If it was the polygon mirror every color should have the same problem no?

[teebee1234]

You have 2 hexagonal mirrors stacked. Cyan and Yellow lasers utilize the top mirror, Magenta and Black use the bottom one. Yellow may exhibit this condition also, but not as noticeable since it's such a light color to begin with. I've seen the trail edge of the mirror surface get "flat" sheen to it (you'll have to look close like herrmann and jon said). This will cause the laser light to scatter at the end of the scan and give light image. If you're going back in, you might just want to replace the mirror motor.

[XXX]

Our Ricoh CL7300 have a problem since a while, affecting only Cyan and only when printing light background, the cyan get lighter at the top of the sheet, here is an image:


We did replace drum and developer, that did not change a thing!

When we print 100% solid Cyan we don't have the problem, the color is the same from top to bottom, but as soon as we print light color that have cyan in it we get inconsistent color on the top 1/3 of the sheet

Anyone have any idea of the problem?

Thanks for the help

I'm guessing that the image transfer belt is the problem.
If you look closely at the magenta bar and compare it to the cyan bar, you can see some similarities.

Have you tried flipping the image so the black bar prints on the left side?

[Hyksos]

The scan is a bit off, the magenta is not fadding, we did some extensive test and it's always the Cyan that fade, the horizontale position (left or right) does not change anything, the cyan is fading over the top 1/3 of the sheet at any position

I did not check very closely the yellow, I'll do more test with lighter color to see if we can see the same problem in the yellow.

Then I'll go clean the polygon mirror... even if it look clean

Thanks for all the answers.

[XXX]

The scan is a bit off, the magenta is not fadding, we did some extensive test and it's always the Cyan that fade, the horizontale position (left or right) does not change anything, the cyan is fading over the top 1/3 of the sheet at any position

I did not check very closely the yellow, I'll do more test with lighter color to see if we can see the same problem in the yellow.

Then I'll go clean the polygon mirror... even if it look clean

Thanks for all the answers.

Don't waste your time looking at the yellow.
And I'd be very careful about handling a mirror motor with surface coated mirrors.
Has anyone suggested what materials you should use to clean it with?

[Hyksos]

No, do you have any suggestion? I was about to use a micro fiber cloth, used to clean plasma TV without damaging the anti reflecting protection.

[E Winter]

These polygon mirror surface isn't more sensible than a scanner-mirror. I use a simple (new) cloth damped with glass cleaner. I think it's important to clean it wet to avoid scratches and get the dirt off properly. Never had any issues related to a cleaned polygon mirror motor and I've cleaned tons of them over the years (anyone remember the A1224 polygon mirror?^^).

[Hyksos]

Polygon mirror cleaned.... no change at all

Is there a newer firmware version, we are on version 1.10? Maybe there's special fix in newer firmware? I really dunno what to check now :/

[teebee1234]

If you've eliminated the mirror motor and the entire laser path then I would say the next step would be to check the transfer. Do you have another transfer unit you can swap out for testing? Otherwise, check the transfer roller itself.