[CQ] Black copies/prints (with text) on Canon iR7086

[Tasso]

Greetings,
I have situation with black copies and prints coming out with text.
I have changed all corona wires, after that complete primary assy, cleaned complete developing assy together with the drum unit and potential sensor, checked back side of transfer separation ground wiring, but the copies still come black.
I have the following reading in Service mode>Copier>Display>DPOT:
DPOT-K 0 V; VL1T 70 V; VL1M 2 V; VDT 390 V; VDM 2 V;
VG-K 592 V; VL1M-P 2V; VL1T-P 70V;
VDM-P 2 V; VDT-P 390 V;
BIAS-P -(minus)167, BIAS-C -(minus)167;
LPOWER-P 128; LPOWER-C 128
VDT-S 260V; VDM-S 2V

When I turned off Potential Control (Option>Body>PO-CNT from 1 to 0), the print seems good.



Every help will be appriciated.

[zoraldinho]

Re: Black copies/prints (with text) on Canon iR7086

Capture.jpgWhen duration of operation period continues, the contact status between the static eliminator brush on pickup
assembly and the pickup roller shaft is changed and the contact resistance may increase significantly. Due to this
phenomenon, charge (static electricity) is accumulated on the pickup roller and noise is generated. Then element on
the DC controller PCB erroneously acts and that causes the abnormal black image.

Change the DC controller PCB with the new type one that has better noise resistance (chip capacitor added).

How to see the new DC controller PCB??

Chip capacitor is mounted on the back of the DC Controller PCB as below.Capture.jpg

Old FM2-4355-110 DC controller PCB

New FM2-4355-120 DC controller PCB

[Tasso]

Re: Black copies/prints (with text) on Canon iR7086

Thanks for the reply.
I will check and post the info

[zoraldinho]

Re: Black copies/prints (with text) on Canon iR7086

Thanks for the reply.
I will check and post the info

You are welcome Tasso.Good luck.

[charm5496]

Re: Black copies/prints (with text) on Canon iR7086

When you were cleaning the machine did you check the drum surface for deep scratches or gouges down to the substrate. Primary charge unit for excessive dirt or signs of wires arcing at the ends. Developer unit for bad bearings or damage to the cylinder. Developer bias HVT.
Does it have the same issue from all paper sources? There have been issues where a clutch was bad causing a similar issue when feeding from deck 1 only.

[zoraldinho]

Re: Black copies/prints (with text) on Canon iR7086

I mist your last post (When I turned off Potential Control (Option>Body>PO-CNT from 1 to 0), the print seems good.)Inportant info!

Try with COPIER> FUNCTION> DPC> OFST

[Tasso]

Re: Black copies/prints (with text) on Canon iR7086

The drum surface wass free of scratces, also I've tried with a new Primary unit. Developing unit seem to be OK. I didn't replace Developer Bias HVT. Will check that monday morning. Also, I've checked clutch on the No1 pick up unit.

When you were cleaning the machine did you check the drum surface for deep scratches or gouges down to the substrate. Primary charge unit for excessive dirt or signs of wires arcing at the ends. Developer unit for bad bearings or damage to the cylinder. Developer bias HVT.
Does it have the same issue from all paper sources? There have been issues where a clutch was bad causing a similar issue when feeding from deck 1 only.

[Tasso]

Re: Black copies/prints (with text) on Canon iR7086

I have allready tried that, but without success. The only change is that setting for Potentional sensor was changed to 29 (factory setting was 22)

I mist your last post (When I turned off Potential Control (Option>Body>PO-CNT from 1 to 0), the print seems good.)Inportant info!

Try with COPIER> FUNCTION> DPC> OFST

[charm5496]

Re: Black copies/prints (with text) on Canon iR7086

I am thinking that it is probably your laser assembly this machine writes black. The laser discharges to drum where the image is which is why you are still getting the white text. Do you have blanking around the edges of your pages?

[nivssluck]

Re: Black copies/prints (with text) on Canon iR7086

you can try change the DC board as what ronaldinho suggested.

One of our customers gave us a copy (pdf file) from Canon about this machines, ir7086/7095/7105 with corresponding serial number that has a laser problem. (factory defect as would say)

[Tasso]

Re: Black copies/prints (with text) on Canon iR7086

There is no blanking aroun the paper. But I repeat, when I disable the Potention control, copy/print looks quite OK, so because of that I dont believe that is Laser Assy.

[zoraldinho]

Re: Black copies/prints (with text) on Canon iR7086

There is no blanking aroun the paper. But I repeat, when I disable the Potention control, copy/print looks quite OK, so because of that I dont believe that is Laser Assy.

einstein.jpg

[Rachid.Akli]

Re: Black copies/prints (with text) on Canon iR7086

VL1T = 70V : This is the reference value ofthe drum potential when the laser is "ON"
VL1M = 2V : This is the measured value of the drum potential when the laser is "ON". It shouldn't be much different than VL1T. (between 60V and 80V) and it is not the case.

VDT= 390V : This is the reference value of the drum potential when the laser is "OFF".
VDM= 2V : This is the measured drum potential with Laser "OFF". In normal conditions it is not much different than VDT(390v) and it is not your case.

When you turned the potential control "OFF", the copy is ok.

So, I think that the potential sensor is not well connected ( coinnetors or wirings) or it not working at all.

[Herrmann]

Re: Black copies/prints (with text) on Canon iR7086

When I turned off Potential Control (Option>Body>PO-CNT from 1 to 0), the print seems good

This is the essential predication!

If the Printouts are ok while PC is turned off, you can assume, that the coronas, developing unit and Laser are good. It's the control system which is running wild.
First at all, i would suggest you to change the potential sensor itself against a new one and see, what happens. Attention: the potential sensor and its pcb belongs together, change only as set!

[zoraldinho]

Re: Black copies/prints (with text) on Canon iR7086

Herminator rules.