BH350 drum life spam

[brianho80]

hey experts,

i encounters that drums for bh350 cannot last for 100k according to the service manual. when come to 60k, drum start with a bit scratch line at the edge which caused by developer magnectic roller Ds Collar. Most of the time, drum get scratched start from Collar then follow by hook at transfer roller.

i'm using Ds collar with bearing which introduce by parts supplier that it is a enhancement of original. I did try with 2 Bh350, the unit with Bearing caused drum surface scractched more easily than the original.

does anyone has this kind of problem?

[Hansoon]

Re: BH350 drum life spam

The modified collars reduce the scratching of the drum dramatically. However, when the mag roller seals are damaged and/or the white plastic guides of the transfer roller are worn a new drum will scratch easily again in spite of the modified collars.

Hans

[brianho80]

Re: BH350 drum life spam

Well, That means every time we replace new drum, we need to check mag roller seal and transfer roller guide condition right....

what i normally did after replace drum is replace the guide at transfer unit (compatible one) because original always come with a set with the roller.

Will the side door caused the drum scratched?

[Hansoon]

Re: BH350 drum life spam

Following parts touch the drum and can cause scratches:

- Mag roller collars
- Mag roller seals
- Transfer roller guides
- Transfer roller collars

There is nothing in the side door coming into contact with the drum or even coming near it under normal conditions except the transfer roller.

Hans

[CraigW]

Re: BH350 drum life spam

Our 350s do pretty well....the low count 200s are another story.

On the 350s we do transfer roller each PM.

We install white bearing collars into all new 200 series developing units when they come in new. (why they are not factory done....? I have no clue)

[brianho80]

Re: BH350 drum life spam

Hi Hans & CraigW, thanks for the advise.

at least i confident in the white bearing collars now. However, most machines i will throw away the transfer roller collars, i don find it useful beside holding the drum.

what do u think?

[CraigW]

Re: BH350 drum life spam

However, most machines i will throw away the transfer roller collars, i don find it useful beside holding the drum.

what do u think?

Not sure what you mean by "transfer roller collars"

[Darren King]

Re: BH350 drum life spam

Following parts touch the drum and can cause scratches:

- Mag roller collars
- Mag roller seals
- Transfer roller guides
- Transfer roller collars

There is nothing in the side door coming into contact with the drum or even coming near it under normal conditions except the transfer roller.

Hans

The dev spacer rollers don't actually touch the conductive surface of the drum, and therefore can't scratch it. The ring produced on the rear end of the drum is, in my experience, caused by the transfer roller, which does touch the conductive surface of the drum. However the dev spacer rollers do wear and cause damage to the seals, which causes dev and toner dumping.
Darren

[Hansoon]

Re: BH350 drum life spam



This line is being caused by the transfer roller guide which rides on the drum. This guide keeps the transfer roller guide plate in a distance to the drum.



Line on drum matches guide.



The thin line besides the broad one is being caused by the roller or "collar" from the transfer roller. (Picture in the middle) This roller keeps the distance transfer roller to the drum surface constant.

Here is a text I wrote for one of my previous posts about the issue:

A) The drum is fixed and steady in its position by the two metal pins molded in the plastic side covers who in turn are fixed to the developer unit base.

B) The nubs on the transferroller bushings ride on the drum surface and are there to keep the distance of the spring loaded movable guide of the transferroller constant to the fixed drum.

C) The thin sharp edged collars sitting beside the transferroller bushings ride on the drum surface and are there to keep the distance of the spring loaded movable transferroller itself constant to the fixed drum.

D) The collars sitting on the end of the mag roller ride on the drum surface and are there to keep the distance of the spring loaded movable mag roller constant to the fixed drum.

H) Between the surface of the fixed drum and the surface of the spring loaded movable mag roller are two mylar seals (or guides). The seals are fixed to the base of the developing unit in the cavity under the mag roller. The seals are than led from under over the surface of the mag roller and are attached to the doctor blade with another adhesive piece of seal.

I) The distance drum surface to the mag roller surface is critical not only for the copy quality but also for providing enough space for both seals.
The distance drum surface to the mag roller is determined only by the size of the collars at both mag roller shafts. This distance decreases, especially that of the rear collar, because of excessive wear (probably caused by abrasive toner/developer particles). At a certain point the collar(s) are weared down so much that the gap between the drum and mag roller is not sufficient to keep the seal from being touched by the turning drum. When the drum surface grabs the seal it will be ripped off in the direction the drum turns, in this case downwards.

Hans

[Darren King]

Re: BH350 drum life spam

This line is being caused by the transfer roller guide which rides on the drum. This guide keeps the transfer roller guide plate in a distance to the drum.



Line on drum matches guide.



The thin line besides the broad one is being caused by the roller or "collar" from the transfer roller. (Picture in the middle) This roller keeps the distance transfer roller to the drum surface constant.

Hans

Exactly

[fixthecopier]

Re: BH350 drum life spam

Hans, you are the go to guy on dv collars. Have you ever dreamed about them at night.

[brianho80]

Re: BH350 drum life spam

Hans, are you involve when they design this model?

anyway thanks for the brief advise,