MP 4000 gray background---

[blazebusiness]

All of us are accustomed to the MP4000/5000 buildup on the developer cylinder by now and the adjustments in the Tech bulletins to minimize fogging/gray background. But this time I have an issue that's a bit different...............

Customer had perfect clean copies with nice bold blacks and according to them,in an instant they had dark gray background. You can see the image being copied ok thru the background. It's like it went from normal toner concentration to overtoned but again----in the blink of an eye. PCU drum is very new and developer was changed maybe 17K ago when the PM160 kit was installed. Back of PCU and developer are clean - and interior of machine and contacts are clean also. Made some skyshots after installing an empty toner to try and tone it down and got an SC350 code. Drum main charge looks clean.

My next step will be to replace and initialize the ID sensor and maybe replace the xfer belt assy. Also thinking about purchasing and installing one of those ground straps NA Trading offers.....Any thoughts/advice appreciated.

[slimslob]

Might be a faulty contact to the charge roller. Also check drum shaft continuity to ground and development unit ground.

[imihm]

All of us are accustomed to the MP4000/5000 buildup on the developer cylinder by now and the adjustments in the Tech bulletins to minimize fogging/gray background. But this time I have an issue that's a bit different...............

Customer had perfect clean copies with nice bold blacks and according to them,in an instant they had dark gray background. You can see the image being copied ok thru the background. It's like it went from normal toner concentration to overtoned but again----in the blink of an eye. PCU drum is very new and developer was changed maybe 17K ago when the PM160 kit was installed. Back of PCU and developer are clean - and interior of machine and contacts are clean also. Made some skyshots after installing an empty toner to try and tone it down and got an SC350 code. Drum main charge looks clean.

My next step will be to replace and initialize the ID sensor and maybe replace the xfer belt assy. Also thinking about purchasing and installing one of those ground straps NA Trading offers.....Any thoughts/advice appreciated.

Hi there...
Check for correct bias...
Thanks..

[nadimtopsecret]

You can clean your Laser Unit properly. If it don't solve then replace the Developer.

[blazebusiness]

Might be a faulty contact to the charge roller. Also check drum shaft continuity to ground and development unit ground.

Slimslob, you are always ready to reply and help-------Thank you. And thanks also to everyone else for responding. Question to Slimslob----------at what points do you connect your multimeter/how do you measure the drum shaft continuity---It is my understanding that the drum shaft bearing is the issue when there is a grounding problem. So I guess we have to take off the back cover of the copier and measure from the bearing to ground or is it from the shaft to the bearing? If you could expound on exactly how you measure the ground continuity.....much appreciated.

And, on a different note----signed on to the TSRC and found this tech bulletin which sounds like it could be the issue the customer is having due to improper position of xport belt assy lever.It certainly would explain the sudden occurrence of the problem. I will attatch it just in case it helps others later.Poor copy quality - SC350 MP4000_5000 TSB.pdf

[slimslob]

at what points do you connect your multimeter/how do you measure the drum shaft continuity---It is my understanding that the drum shaft bearing is the issue when there is a grounding problem. So I guess we have to take off the back cover of the copier and measure from the bearing to ground or is it from the shaft to the bearing? Poor copy quality - SC350 MP4000_5000 TSB.pdf

Measure from the drum shaft to ground or to the outer race of the bearing. The bearing is supposed to be conductive but will eventually lose it conductivity. If you look at the parts catalog Drive section 2, item 18 is the ground contact for the outer race of the drum shaft bearing. It could be loose or not making contact to the race.

[Oze]

Whenever I go to one of these for CQ issues I always check the charge voltages before doing any work to see if it's moved away from the default 1500.
I remember that if you install the PCDU and you miss one of the setting steps you'll get a backgrounding issue.
I usually fit the pcdu and do all the process setting steps and run off at least 50 copies to see if the backgrounding is gone but skip a step and it usually returns.

[blazebusiness]

Whenever I go to one of these for CQ issues I always check the charge voltages before doing any work to see if it's moved away from the default 1500.
I remember that if you install the PCDU and you miss one of the setting steps you'll get a backgrounding issue.
I usually fit the pcdu and do all the process setting steps and run off at least 50 copies to see if the backgrounding is gone but skip a step and it usually returns.

Checked all the values including charge in service mode and they seemed ok with the exception of the ID sensor readings. Reinitialized the ID sensor after cleaning the sensor. When you say if you miss one of the steps......do you mean perhaps performing the the 2801 and forgetting to do the 2805 adustment?

[NeoMatrix]

Had one of these (4000/4500) years ago with a simliar over tone problem.

Hang on I'm scratching around in the grey matter database. <add smoke here>

After Numerous low k developer replacements .We blocked the toner supply off , run about 15 or 20 sky shots to restore the TD level, and intialised the Td. As a last desparate resort we had it on manual toner supply at Xgms per copy. Adjusted the dev bias to compensate. And of coarse update to the latest firmware at that time.

We could get the TD level to behave to the next PM,only just.

[blazebusiness]

Gonna go out to that machine this week and install the SP 8200A kit which I picked up for a song,replace the ID sensor(overkill-I know) and run all the SP's. And install the NA trading ground strap and start making the customer use the NA trading toner which , as far as I've read , has glowing feedback and not one complaint. This customer will be my tester for those products. We'll see if it helps to keep background issues away.

I guess this is a good time as any to expound on the differences between the SP8200 PCDU and the MP 4000 PCDU as I've come across misleading info in other posts.These units are not "ready to go"....

When you get a SP8200 PCDU you need to replace the front gray cover with the MP 4000 cover. Don't throw away the SP 8200 cover as it has a full new developer/starter powder inside which you can use to setup the dv unit. Remove the PCDU new unit detect assy from the back(brown plastic thingy next to developer drive) and remove some funny metal latching pieces on the top of the PCDU by removing 2 eclips and pulling out the metal pins and you are done.