Savin 3528C (aficio 3235 B178) heavy background on black while printing

[Desert Rat]

It started out as a barber pole type bands, these are diagnal bands. It also gave a set
dev station message. I went through this on this unit with the cyan, then it was the
yellow. So I replace all the dev drive clutches, the cyan and yellow dev stations,
because of a low mix condition caused by the clutches. That went fine for about
a week.
Now when they print 20 or more pages, from the doc server,the black starts
producing heavy bands, even when doing just one color. I made 35 copies on black and they all came out fine. Ran more from the doc server then
I looked at the black drum unit and the charger roller was covered with toner.
So I cleaned it off.
A friend suggested that it was a hdd problem so I reformatted. That was no good.
I unplugged the hdd and made copy that was no good. I made only cyan copy
and it still had black back ground.
the drum count is 100K +. I know it is time to replace it. I also tried a different Blk dv
station. Accidently reset the drum instead of the developer. Now it does this
banding background on everything copied or from the doc server.
I intend to replace the drum.
It is also not adding black toner or at least it does not know that it is. I can hear
the air pump. But am not sure about the assembly above the black developer unit.
I am not sure of where to step next on this machine.
What else will I need to do or not do?
This customer has two of these machines.

Thanks

DR

[tcs04]

Sounds related to RTB attached

[Desert Rat]

TCS4
Thank you for the tech letter, I have that one. That is how the problem started out. As mentioned
I replaced all the dev clutches in this unit. And the yellow developer station. That problem went away
and the machine ran fine for a week.
Now it is over toning on the black, even when I choose a single color. Example; I ran cyan only and still
have the black back ground. The charge roller for the black drum is not cleaning off and is coated with
toner as is the drum.
I did a toner refresh on the black. Now it is trying to add toner to the black unit and it either is not
or does not know it has. I don't have the option of trying a different black developer unit or drum
yet. I am still in the scratching my head phase and reading the theroy guide for a clue.
First I will have to get know good drum and developer units.
This customer bought these at an auction and there was not any service documentation.

Thanks for your input

DR

[tcs04]

Could be it's gradually dumped the dev and is replacing it with toner? I've seen this before and they do run fine for a while until the dev level drops. This would throw the TD off, possibly add MORE toner and give the background, especially if there is no dev to hold the toner onto the mag roller. I suspect you either have a duff clutch (again!?) or something is causing it to stick on mechanically. I assume there's an active low trigger for the clutch, if this is always low (faulty PCB?) it would lock the clutch on.

[nick40]

TCS4
Thank you for the tech letter, I have that one. That is how the problem started out. As mentioned
I replaced all the dev clutches in this unit. And the yellow developer station. That problem went away
and the machine ran fine for a week.
Now it is over toning on the black, even when I choose a single color. Example; I ran cyan only and still
have the black back ground. The charge roller for the black drum is not cleaning off and is coated with
toner as is the drum.
I did a toner refresh on the black. Now it is trying to add toner to the black unit and it either is not
or does not know it has. I don't have the option of trying a different black developer unit or drum
yet. I am still in the scratching my head phase and reading the theroy guide for a clue.
First I will have to get know good drum and developer units.
This customer bought these at an auction and there was not any service documentation.

Thanks for your input

DR

I think your black PCU might be bad. I had a few go bad on me were the charge roller would be coated with toner and it would put a background on my pages. I always replaced both developer and PCU at the same time.

[Desert Rat]

Nick,
I have picked up a used drum and dev to use as a test to see if I can strike a nerve. I am not
real familar with this model. So I do not know what it does when it wears out a drum.
I have seen what happens when the dev clutches go out. And I know sooner or later the
drums will wear out. This customer got this from an auction or something. There was not any service
history on this unit to refer to. How often do the clutches over the developer units
for the toner pump wear out? Someone told me they have replaced 3 or 4 this year. But
I have no idea how many of these machines he services.

Thanks for your advice. I will replace the drum today.

DR

[nick40]

I serviced a fleet of 125 of this machines for about 2 years until they upgraded. During that time I replaced many clutches but I did not find a pattern. The symptom was always the same customer would call for diagonal bands and I would have to change the developer unit and clutch.
As far as the pcu, when they are worn out you will begin to see a coat of toner on the charge roller. Sometimes just a line and in some cases the whole length of the roller. At that point I think you can try just replacing the PCU and them run some solid copies to de tone the developer. I never tried it but if you got the time and want to same some $$ it might be worth it.
During those 2 years I never had any toner pumps go bad but from what I heard from the other tech it is very time consuming to replace one.

[Desert Rat]

Nick,
Good post. That sounds like what I have been going through. I have a new oem drum and dev
unit to install in one of these machines.
The other machine is just keeps trying to add toner. It was working fine and then someone broke
the nozzle in the center of the black toner hopper. I replace the hopper and now all it want to do is
add toner to the black developer unit. My thought was the black toner pump on top of the
developer station ran out of toner and damaged itself when the line ran dry of toner.
What do you think? Sound likely?
Or does it just need another developer station?

Thanks for the great post

DR

[Desert Rat]

Ok, this problem is driving me nuts.
I put the new oem drum and developer in, according to the book, resetting the pcu and dev turn off, replace, turn on.
The message was developer black not set correctly. Thinking this was a bad connector. I pulled the black dev
connector out and fitted it to the station & inspected it with a magnifying glass. No damage, no loose connectors.
No damaged wires. Everything looked ok, but still the dev not set message. Just for grins and giggles, after 3.0 hrs
of fun, I reset the dv unit and installed the old dv unit. Message went away and the copies came out fine.
I suppose it is possible that I got a bad TD sensor on the new unit. But this still seems a bit of a mystery to me.
The drum unit fixed the heavy background.
So just to make my day more interesting, this guy from the back sez the other machine just like this one does not
print everything in color. I will make a new post for this. I think this is an IT problem?

Any comments on what happen here would be appreciated...

Thanks

DR

[Desert Rat]

That other Savin 3528C that was always asking for toner. I ended up replacing the toner hopper
for a broken nozzle and the black toner supply unit with clutch. The part above the developer
station. The book has you tear down more than needed. This was a royal pain in the ass!!
I checked the line for lumps, none found. I used the output programs to check the different
functions. Example turn on the dev drive motor, then the toner supply clutch, then the toner
air pump. Open shute under toner supply unit and toner should come out. And at a pretty good
rate too. When I did this for the yellow it came out pretty quick but nothing for the black.
After changing the pump the problem went away and it made pretty good copy, all things
considered.

Thank you everyone for your help

DR