Canon MF-817OC

[jose antonio]

HI,
just finished servicing a canon MF-8170c, and when checking found that when scanning a B&W document the copies come out blank, colored documents come out full magenta,text and other colors come out blue, white backgroud also in magenta.
Print outs are ok, so must be something with the reader scanner.
Anybody had this strange problem?

Any tips appreciated,

Machine had this problem before the service.

[blancomputer]

Re: Canon MF-817OC

HI,
just finished servicing a canon MF-8170c, and when checking found that when scanning a B&W document the copies come out blank, colored documents come out full magenta,text and other colors come out blue, white backgroud also in magenta.
Print outs are ok, so must be something with the reader scanner.
Anybody had this strange problem?

Any tips appreciated,

Machine had this problem before the service.

From what you are describing the main scanner unit is faulty on the printer. Before replacing it check all the connections for the scanner reader unit 1st that connect to the main controller board found sometimes if it not making a correct connection give the above problems. board between the DC controller and the main controller.
let know what other problems the printer had
brett
canon service

[teckat]

Re: Canon MF-817OC

Backtrack your service procedures

did it have that issue before service

[jose antonio]

Re: Canon MF-817OC

From what you are describing the main scanner unit is faulty on the printer. Before replacing it check all the connections for the scanner reader unit 1st that connect to the main controller board found sometimes if it not making a correct connection give the above problems. board between the DC controller and the main controller.
let know what other problems the printer had
brett
canon service

Checked the connections on the scanner reader only, have to check the others on main and DC controller.
Haven't worked on these printers for some time now.

Will let you know tomorrow when I get back to the shop, Thanks!

[jose antonio]

Re: Canon MF-817OC

Backtrack your service procedures

did it have that issue before service

It had this problem before, they used it for printing only and now they want it to scan for making copies.

[jose antonio]

Re: Canon MF-817OC

Checked all connections on scnt and ncu boards under the reader assy,problem stayed the same but machine prints ok.

I'm not sure witch one of these boards could be causing this strange problem; black & white copies come out blank, colored documents come out completely covered in magenta with dark blue text, original text is in B&W.

[teckat]

Re: Canon MF-817OC

Checked all connections on scnt and ncu boards under the reader assy,problem stayed the same but machine prints ok.

I'm not sure witch one of these boards could be causing this strange problem; black & white copies come out blank, colored documents come out completely covered in magenta with dark blue text, original text is in B&W.

The laser/scanner system forms a latent image on the photosensitive drum according to the VIDEO signals sent from the SCNT Board.
This system consists of the laser driver circuit, scanner motor, etc.
They are integrated into the laser/scanner unit and controlled by the DCNT Board.

1) The DCNT Board rotates the four-sided mirror when a print command is sent from the SCNT Board, and then rotates the scanner motor.
2) When the scanner motor starts to rotate, the DCNT Board emits light from the laser forcefully with the LASER CONTROL signal and then starts to control the rotation of the scanner motor.
3) The DCNT Board rotates the motor at a specified speed with the SCANNER MOTOR SPEED CONTROL signal.
4) The DCNT Board sends the VIDEO signals to the laser driver circuit after the rotational speed of the motor reaches its target value.
5) The laser driver PCB emits light from the two laser diodes according to these signals.
6) The two laser beams strike the four-sided mirror rotating at a specified speed through the collimator lens and cylindrical lens.
7) The laser beams reflected off the four-sided mirror focus on the photosensitive drum through the focus lens and reflective mirror located in front of the four-sided mirror.
8) When the four-sided mirror rotates at a constant speed, the laser beam striking the photosensitive drum scans on the drum at a constant speed.
9) When the photosensitive drum rotates and the laser beam scans on the photosensitive drum, at each specified speed, a latent image is formed on the drum.

[jose antonio]

Re: Canon MF-817OC

Looks like it's going to be an expensive fix, replacing one of those boards.

I think I'm going to try swap the reader scanner lamp with the flat cables first, before taking to the boards.

Thanks!