bizhub 350 copy problem

[goldencup]

Hi, I would like ask if you have encounter this problem on bizhub 350.
I did replace a different developing unit (3 units from a good machine). At first copy operation, the image is good then after maybe 60 copies the image started to get dirty. I think there is something in the machine that is causing this... any idea? Any adjustment that I should do or something that I should check? Thank you very much

[goldencup]

Re: bizhub 350 copy problem

...by the way when I look at the drum, it looks like there is no problem and still in good condition, also checked, cleaned and change the charging assembly.

[Benjamin1976]

Re: bizhub 350 copy problem

I would check your contacts for the drum unit, In one of your samples I can see an image of the charge grid. I would try a different drum unit if the drum contacts look good.

[Hansoon]

Re: bizhub 350 copy problem

I agree, something with the contacts perhaps.

How about the discharge lamps? What bothers me is the pattern however.

Next time you post samples please indicate the feeding direction with an arrow.

Hans

[WildbillC]

Re: bizhub 350 copy problem

You say you replaced the dev unit. Did you also replace the drum, because it looks like drum ground issue to me.
I think everyone agrees its some kind of contact issue.

[fixthecopier]

Re: bizhub 350 copy problem

We just had one spraying toner and making poor quality copies. Background was dirty. Found the erase lamp not working.

[pepper38_cnd]

Re: bizhub 350 copy problem

Since each time you change the dev unit , the copies were good until about 60 copies and then it got worse from there? Is it possible the your customer got the wrong toner into the machine? If you put a dev unit back into the working machine you took it out of does the problem follow? Note swapping dev units on this series usually results in a code unless both machines are relatively new drum and dev.

[goldencup]

Re: bizhub 350 copy problem

regarding toner issue all are originals, I did clean and even change the grid and charging assembly. Also I've check the contact inside the drum and also replaced the drum. What puzzles me is that if I test the problematic developing on the GOOD machine, the problem is still there. By the way I test the good developing unit on the problematic machine and wait for the problem occur. When the copy problem appear, I return the developing unit back on the GOOD machine, now the copy is not good too. I did it on two more good developing unit, same thing happen (I think something in the problematic machine makes the drum unit like overcharge maybe or whatever???) Anyone have encounter this? What do you think is causing these problem? [attached are my new sample copy] Thank you

F12 600dpi..jpgconfig 600dpi..jpg

[pepper38_cnd]

Re: bizhub 350 copy problem

You just answered the question, if you put a good working developer assy in the machine and it is destroyed and no longer works in any machine then you have a toner problem ( it doesn't matter if you have verified that the now installed toner is OEM ) there is definitely the wrong toner in the toner hopper! That is the only thing that would move back to the previously working machine from the non working machine.

[goldencup]

Re: bizhub 350 copy problem

thanks for the reply. As I continue my observations here, I try to separate the developing unit: The Upper Part (with Drum,Blade,Charging) and The Lower Part (with Developer). I put the Lower Part (the one with copy problem) on the Upper Part of the GOOD unit and test it. the Lower Part is OK! therefore I have no problem with the toner. Same with the other two unit that was also affected. I now test the Upper Part (the one with copy problem) on the Lower Part of the GOOD unit and test it, now the copy problem appear as seen on the previous attached images. Which now I focus my attention on the Upper Part. I test the charging and the drum also one by one and now found out that the problem is the drum (though it has no damage and really in good condition if you look at the drum physically).By the way, these are all performed on a GOOD working machine. Given that the drum is the problem and can easily be replaced, the problem is that if i put it back on the problematic machine , it might damage the drum again . Something in the machine is still damaging the drum. I was hoping some of our friends here might have encountered this and solved this mysterious problem.
Thank you very much for all help and suggestions

[Hansoon]

Re: bizhub 350 copy problem

Just some thoughts:

The tiny white dots inside the black pattern are very symmetrical. Do they correspondent with the drum separator claws? If yes, than there are two things coming to mind: A) Stray light shining on the drum (not likely cause its too even spreaded from front to rear) or somehow a charge coming from the transfer roller on the drum. The latter could mean a defective HV unit. Did you check those drum discharge lamps by the way? Are they going on AND off?

Hans

[Hansoon]

Re: bizhub 350 copy problem

Just some thoughts:

The tiny white dots inside the black pattern are very symmetrical. Do they correspondent with the drum separator claws? If yes, than there are two things coming to mind: A) Stray light shining on the drum (not likely cause its too even spreaded from front to rear) or somehow a charge coming from the transfer roller on the drum. The latter could mean a defective HV unit. Did you check those drum discharge lamps by the way? Are they going on AND off?

Hans

[goldencup]

Re: bizhub 350 copy problem

Just some thoughts:

The tiny white dots inside the black pattern are very symmetrical. Do they correspondent with the drum separator claws? If yes, than there are two things coming to mind: A) Stray light shining on the drum (not likely cause its too even spreaded from front to rear) or somehow a charge coming from the transfer roller on the drum. The latter could mean a defective HV unit. Did you check those drum discharge lamps by the way? Are they going on AND off?

Hans

hi sir hans, yes they do correspond with the claw, I was also thinking of some kind of light but I have no idea where it could be coming from. How can I see the discharge lamp going on and off I removed the back cover but all I can see is the glow of the heater lamp

[Hansoon]

Re: bizhub 350 copy problem

Are you able to swap the HV unit? (PM Page 9 position 3, behind the image unit)

Hans

[pepper38_cnd]

Re: bizhub 350 copy problem

Ok I was confused, I thought originally that you were just changing the Developer unit. Now I realize you were swapping the entire Image unit which consists of both the drum assy and the developer assy. You have narrowed the problem down to the drum assy. Can you see physical damage to the drums that have been tried in that machine? Did this problem just occur, or did it start after some sort of servicing?

Since you say the copy starts out good and then deteriorate after about 60 copies. I would not think it is not a contact problem. The light striking the drum, sounds possible but the problem occurs when the machine is running and the drum is turning not after the drum has been sitting still. I guess you could verify if it is actually the drum by taking the DRUM Only ( not the Drum Assy ) out of a non working unit and placing it in a working unit, and testing. If the problem follows then something is destroying the drum.

Is it possible that each drum cleaning section is being compacted with toner ( possibly the recycle tube on the toner hopper is plugged ) ?