[Misc] Can I test the high voltages?

[sbtiti]

We are working on a WC 4260 but same issues could be similar on a 4150 or 4250.

I have replaced the drum and the toner but still getting a grey print instead of black. It appears that the drum is not attracting enough toner since a half print test shows more of a grey print on the drum. I have cleaned the LSU window so am assuming that the issue has to do with the high voltage, but I would like to be able to test for that instead of just following the service manual and replacing the HVPS.

I would really appreciate anyone comments or help. Thank you.

[blackcat4866]

Re: Can I test the high voltages?

Not since the analog days. We used to have a device that you would install in place of drum. There was a little sensor that aligned with the primary charge. You would plug it into your VOM, enter the appropriate service mode, then turn the VR on the HVT to get the desired value.

As far as I know noone ever actually used it. After a few years of working on copiers, you develop a sense of how dense the image should be with new developer/charge/primary wire. Once the charge was right, then you can adjust the lamp intensity for a correct density with minimal background.

That all being said, modern MFP's automatically set high voltage, grid voltage, developer bias, transfer, secondary transfer, separation voltage without any technician intervention.

It might be more helpful to do an emergency stop with a print in the machine, and see if there is a good latent developed image. =^..^=

[KenB]

Re: Can I test the high voltages?

I think we had a high voltage probe that would connect to a VOM.

But that was back about 1980 (not kidding), and I really don't remember anyone actually being brave (or perhaps crazy) enough to actualy use it.

[NeoMatrix]

Re: Can I test the high voltages?

Is there an "ecco toner" mode to save on toner?
Can it be changed at the MFD or at the PC software printer properties setting?

[subaro]

Re: Can I test the high voltages?

Is there an "ecco toner" mode to save on toner?
Can it be changed at the MFD or at the PC software printer properties setting?

This is worth checking.
Yes there is. Below is from the user manual. I have been caught by this feature a few times before and started to replace parts only to find it was this simple. Even though i know to check this feature when troubleshooting, it somehow still eludes in the heat of things.

WC 4250
Toner Saver If you are printing draft documents you can reduce the toner (dryink) used by using the Draft Mode feature. The image will be lighter than normal but will be legible and ideal for checking or proof reading a document. To conserve toner, click the Advanced tab and open Image Options. In Draft Mode select On.

In this case,you will want to turn draft mode to OFF

[NeoMatrix]

Re: Can I test the high voltages?

I think we had a high voltage probe that would connect to a VOM.

But that was back about 1980 (not kidding), and I really don't remember anyone actually being brave (or perhaps crazy) enough to actualy use it.

Back in the day we would use a current probe, directly onto the corona wire. You can make a current probe yourself from 10 @ 1Mohm 1watt resistors all in series. I made one an incased it inside a rubber tube filled with fibre-glass resin. A wire at the top of the probe plugged into your volt-meter.

The old old Toshiba's had a special drum voltage measurement tool. In effect it was just a partial cross section of an actual drum with two wires coming off the device where you plugged in your volt-meter. You would put the machine in corona test mode and measure off the voltage. While in test mode you would adjust the trim-pots at the back of the machine as you watched the volt meter. There was no soft switch adjustments through the front panel in those days. From memory...looong ago. I believe the measurement was in millivolts.

[sbtiti]

Re: Can I test the high voltages?

Not since the analog days. We used to have a device that you would install in place of drum. There was a little sensor that aligned with the primary charge. You would plug it into your VOM, enter the appropriate service mode, then turn the VR on the HVT to get the desired value.

As far as I know noone ever actually used it. After a few years of working on copiers, you develop a sense of how dense the image should be with new developer/charge/primary wire. Once the charge was right, then you can adjust the lamp intensity for a correct density with minimal background.

That all being said, modern MFP's automatically set high voltage, grid voltage, developer bias, transfer, secondary transfer, separation voltage without any technician intervention.

It might be more helpful to do an emergency stop with a print in the machine, and see if there is a good latent developed image. =^..^=

Thank you for your response and help. One of the replies I received mentioned that it could be in "toner saver" mode, but I assumed that the Clear-All button would cancel that. I have been all through the menus on this 4260 and have found no such option for Toner-Saver anyway.
I believe I have performed your "emergency stop" by opening the right side door during the print cycle and then checking the density of the toner printed onto the drum: I cannot be sure, but it appears to be too light on the drum also and since I have already replaced the drum, without success, I'm not sure what my next step should be. Any further assistance would be greatly appreciated.