Avantra 25 Low Density in half page

[tekcontrol]

I've a problem with a Avantra 25, randomly it prints a page with a very low density. Sometimes half (or part) of the page has a normal density and the other half does not. Even the density test shows the same issue, and the problem is coming more often. Any ideas?

Regards:

[tekcontrol]

Thanks for the answer, I'm not sure if the problem is the same with other resolutions, it mostly works 2400. The problem is the same at 50%. The problem seems to be that the points are not complete. It seems that the points are only partially draw.

[VladCanada]

Are you able to make a picture with a good magnificy?
There are a few reasons for that issue, including LaserDriverModule problem.

[tekcontrol]

Here are two sambples of the problem, please notice the labels "ok" and "fail". The left side is a regular image, and the right side shows the problem, all at the same imaged file.

[IMG]/Users/eduardorevuelta/Desktop/•••De Eddy/ ••Clientes/Miguel Salazar/IMG_2484.jpg[/IMG]


[IMG]/Users/eduardorevuelta/Desktop/•••De Eddy/ ••Clientes/Miguel Salazar/IMG_2485.jpg[/IMG]

[tekcontrol]

Sorry, here are the pictures.

[VladCanada]

Bad PWM of the laser diode or bad LD itself...
Laser Driver Module is under my suspiction.
Do you have a pocket X20 microscope?
I woul be curious to see the whole page with 100% black pattern

[tekcontrol]

I print 1200, 2400 and 3600 density tests and all of them are ok. As I mention it does not happens all the time.

I don't have a 20x magnifier, but later I'll try to fin one and take a better picture.

If the error appears in a 100% screen shows it as a very low density print. Reading it with a densitometer it measures a 20% screen.

Other issue that maybe helps to find the error, sometimes it prints as the samples (see the three images it suppose to be a 100% screen)

[VladCanada]

99% laser diode, bad modulation.
I've never seen good fix results without a Field Serviceman on-site and spare SGM in his trunk.

Farshad, the spinner can make a squeaking noise when you turn the mirror in wrong direction.

[VladCanada]

Agree,
That's the easiest way to "sort apples and oranges".
If Avantra works in bad environment, that possible cause of spinner's unstable rotation because of the dust contamination in air-bearings, but the image corruption is pretty visible.

[techno]

i came across similar density issues on avantra 25 many years ago
it was the Velcro strip dangling and moving in front of spin motor