Canon ir5000 potential control

**bojans** · 04-09-2010

HI

What about potential control on these machines? Can someone explain is it suppose to be ON or OFF ? I had some problems with background on two machines.Someone was playing with bias and primary corona settings.
I restrung coronas and changed bias settings and solved problem.... Turning ON or OFF potential control doesn't make a difference with copy. I ask this because one machine is ON, second is OFF..

Shall i left it with these settings or change both to ON or OFF.

Thanks

**D_L_P** · 04-09-2010

From what I understand when you turn off potential control it uses standard presets for charge, bias and transfer. I've been told its best to leave it on. In your case PC must only be making miniscule adjustments so the difference is very slight.

The sensor takes several readings of drum potential and then makes adjustments to charge, bias, and transfer. VD, VL and VT. VD- measured without exposure, VL- measured with exposure and VT- Voltage target. Most models the target is -670(?). If its like -600 copies will be light, and -690 will have nice solids. I have been told to adjust DENS-ADJ or EPOTOFST if I am still having copy quality issues.

Now, in the real world those don't always work, so how do you adjust for light copies? Bad ideas are adjusting the height of the corona wire, or set screws on developer bias. Best way is to give it a good cleaning and replace wires. Might be time for a new drum or Dev cyclinder. In my experience a new dev cyclinder has always made big difference.
Some are stubborn and don't want to make a nice solid black though (or even brand new out of the box). It can vary from one model to the next but here are a few things I've found:
Good old NP6650, there were 2 VR's on the HV unit, adjust those and you could get one hell of a solid black.
IR5000 I've had some luck adjusting CCD ->SH-TRGT
IR5570 DENS adj has actually worked some for me.
IR7105 I'll have to look up the exact name, but there was a developer speed adjust (range was like 0-3) that made a HUGE difference for a nice solid black.

Hope this helps.

**bojans** · 04-09-2010

Thanks for exhaustive reply D_L_P

Of course best thing is to clean it well, and I did it.
I had solid black on these two, but problem was when customer wanted to make lighter copies, and set it on control panel they get background and strikes (almost invisible). I had to bring back original settings and adjust the height of the corona, after that i got perfect copy.

Thanks again

**mrfixit51** · 04-09-2010

I agree with D_L_P about leaving potential control on as a default, and I believe the value is set to "0" for on, and "1" for off...

**D_L_P** · 04-09-2010

Adjusting copy quality can be challenging on Canon's. I think setting the corona too close to the drum kinda fries it and might not last as long as it should, but you gotta do what you gotta do to get them going. Any luck adjusting CCD->SH-TRGT?

Another option is adjusting the resolution instead of the light/dark for digital copiers. The default is Text/Photo but I've found "Text" will make things darker while "Photo" will make them lighter. I've had good luck with setting default to Text.

I might have those reversed VD-without exposure, VL-with exposure. Anyway, VD is the one you want to look at and adjust for.

**bojans** · 04-09-2010

I'm going to leave it as it is... until next call. I'm convinced these machines will work without problem. But next time I'll try what you suggested.

Regards