C250i No yellow on rear side of page

[B0265]

We are struggling with a C250i and I'm hoping someone have any suggestion.
There is only yellow toner on about 6 cm in the front side fading from front to rear. Also you can no see the steps on the gradation prints like you can se on C,M and K.
The plack prints are a bit grainy but I don't know if this is related to the Y problem.
So far we have replaced Y drum, Y developing unit, transfer belt, high voltage board, PH unit, base board, and EXCB.
The total counter is 48000, OEM toner and the machine is clean inside.

[Cantechman]

Re: C250i No yellow on rear side of page

C250i No yellow on rear side of page


We are struggling with a C250i and I'm hoping someone have any suggestion.
There is only yellow toner on about 6 cm in the front side fading from front to rear. Also you can no see the steps on the gradation prints like you can se on C,M and K.
The plack prints are a bit grainy but I don't know if this is related to the Y problem.
So far we have replaced Y drum, Y developing unit, transfer belt, high voltage board, PH unit, base board, and EXCB.
The total counter is 48000, OEM toner and the machine is clean inside.

Have you tested the toner supply motor for yellow?

[Synthohol]

Re: C250i No yellow on rear side of page

was the laser glass cleaned with the wand?
did this happen before or after some type of service?

[B0265]

Re: C250i No yellow on rear side of page

was the laser glass cleaned with the wand?
did this happen before or after some type of service?

We have replaced the PH unit twice (two different units).

[B0265]

Re: C250i No yellow on rear side of page

Have you tested the toner supply motor for yellow?

No but the problem remains right after replacing the developing unit, did first test with a unit from another C250i then with a new unit.
The TCR value is a around 7 so I think the toner supply works.

[allan]

Re: C250i No yellow on rear side of page

Did you convert a K unit drum or developer to Y? The mag roller is not camming up to the drum on the one side.
If you use anything but correct DV or DR there are some mods to be done.

Or something is seriously obstructing the laser path.

[tsbservice]

Re: C250i No yellow on rear side of page

I would Remove DV unit and check mag brush. If there is even brush then I would stop machine midcopy solid yellow pattern and check the drum etc. You need to isolate the problem a bit I think.

[copier tech]

Re: C250i No yellow on rear side of page

We are struggling with a C250i and I'm hoping someone have any suggestion.
There is only yellow toner on about 6 cm in the front side fading from front to rear. Also you can no see the steps on the gradation prints like you can se on C,M and K.
The plack prints are a bit grainy but I don't know if this is related to the Y problem.
So far we have replaced Y drum, Y developing unit, transfer belt, high voltage board, PH unit, base board, and EXCB.
The total counter is 48000, OEM toner and the machine is clean inside.

Is the yellow drum & DV unit racked into contact with each other correctly? Looks like they not racked in evenly, check the rear locking arm etc.

[B0265]

Re: C250i No yellow on rear side of page

Did you convert a K unit drum or developer to Y? The mag roller is not camming up to the drum on the one side.
If you use anything but correct DV or DR there are some mods to be done.

Or something is seriously obstructing the laser path.

No converted units, the problem started with the factory installed units and we have only used OEM parts during the trouble shooting.
It looks like something might obstruct the laser path but I can't see what that might be.
Since we have tried with two other PH units it's not in the unit or on the slit glass.

[B0265]

Re: C250i No yellow on rear side of page

I would Remove DV unit and check mag brush. If there is even brush then I would stop machine midcopy solid yellow pattern and check the drum etc. You need to isolate the problem a bit I think.

The coating on the developing roller looks fine, it's even all over the surface.
I have never stopped the machine during printing and tried to pull out a color drum when the 1st transfer roller is in the down position, can this be done without any damage?

[B0265]

Re: C250i No yellow on rear side of page

Is the yellow drum & DV unit racked into contact with each other correctly? Looks like they not racked in evenly, check the rear locking arm etc.

It's difficult to see if the drum and dev units are in contact in the rear side but the dev unit release arm looks fine as far as we can see.

[tsbservice]

Re: C250i No yellow on rear side of page

The coating on the developing roller looks fine, it's even all over the surface.
I have never stopped the machine during printing and tried to pull out a color drum when the 1st transfer roller is in the down position, can this be done without any damage?

Yes drum can be pulled.

[Gift]

Re: C250i No yellow on rear side of page

Haven't read the whole story here but did you try and interrupt the print process (open cover during printing) and check the image on the drum/itb surface?

[B0265]

Re: C250i No yellow on rear side of page

Haven't read the whole story here but did you try and interrupt the print process (open cover during printing) and check the image on the drum/itb surface?

Not me personally but P8 & P21 is shown all the time so I'm pretty sure the yellow image is missing on the transfer belt.

[allan]

Re: C250i No yellow on rear side of page

Could also be a broke part on the TBU that press the primary transfer roller down. So hope stopping the machine and pulling the drum could help a bunch.
You did mention changing the TBU.

Under service mode try to adj the primary transfer current to both extents and see if it will do more or less than that 6cm. Its not to far fetched to be a HV current leakage.