HP M775F alignment issues

alexsmith2709 · ‎10-07-2020

Hi,

We have an HP MFP M775F which has alignment/calibration issues. We have had this on and off over the years but was been getting progressively worse and it is now at the point where it will not go back in to alignment no matter what we do.

I have linked to a PDF of the print quality diagnostic pages. You can see that the 3 colours are not in alignment with the black. Sometimes each colour is not in alignment with the others either.

https://we.tl/t-hOpnVIkLlL

What I have tried:

Full Calibration

Reset Calibration

Laser Scanner Glass Cleaning

Cleaning Page

Cold Reset

Changing cartridges (Both OEM and non-OEM types)

Changing ITB

Checking ITB motor for damage

Changing Registration Sensor

Changing Laser Scanner Unit

Is there anything else that could cause this issue?

Thanks

Repairatrooper · ‎10-07-2020

First thing I note is that our samples look extremely light or faded which could be an indication of power problems such as a faulty High Voltage board or simply inadequate power at the location that the pinter is installed at. Are these pages printed feeding long edge first or short edge first? Are you using OEM supplies or 3rd party?

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alexsmith2709 · ‎10-07-2020

Hi Repairatrooper,

Thanks for your reply.

The scans do look light, but the actual printouts are not. The cyan line down the green section of the second page is noticeable though. They are printed long edge first and are coming from tray 4 of the machine.

Now that you mention it, occasionally on a block of colour such as a background, the colour may fade in patches, is this the high voltage board issue?

Could a high voltage board issue cause the alignment issues or would this just be the light/faded print issues? From the repair manual there appears to be 3 boards with high voltage in the name, which one would be the faulty one?

Currently we have 3rd party supplies, but we have the same issues with OEM supplies. I only have an OEM black to hand and dont want to buy more OEM colours if this machine is about to die as they are extremely expensive!

Thanks

Repairatrooper · ‎10-07-2020

Voltage or light print can cause alignment issues as the alignment patches laid onto the transfer belt may not be read properly resulting in misalignment.

If you find the information provided useful or solves your problems, help other users find the solution easier by marking my post as an accepted solution. Clicking "yes" on "was this reply helpful" also increases the chances that this solution will help others.
I am a volunteer, offering my knowledge to support fellow users, I do not work for HP nor speak for HP.

alexsmith2709 · ‎10-07-2020

Do you know which board it is likely to be as there are 3 with high voltage in the name. Off the top of my head I believe these are:

First high voltage power supply

Second high voltage power supply

Image developer high voltage power supply

Or could it be any of these 3?

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