First case of developer burn in nearly a decade.

[blackcat4866]

Back when I worked on Canon's we called it developer burn. Essentially, the developer spacers would wear or break (which they did a lot), then the drum would get close enough to the mag roller and arc. On the Canon's that meant pits in the ASi drum.

Now to today. It's an e Studio 355, and I think I can re-construct the course of events:

First call 4 days ago: Noise. Tech "adjusts dev unit"

Second call: Bars of developer crossfeed. Replace drum and dev-kit.

Third call: Bars of developer crossfeed. Replace drum, again.

Fourth call: Bars of developer crossfeed. This one's me. The drum is clearly pitted at the machine rear, and the developer is piled up on the upper developer seal. What I think happened is that the developing roller started to wobble some, just due to normal wear and tear. When it wobbles the ribbed surface grazes the doctor blade making a really annoying cyclic sound. Rather than figuring out why the roller wobbles, tech #1 widens the doctor blade gap (significantly). Now the mag brush is nearly twice as high at the rear, same affect as moving the mag roller closer.

Naturally, I don't have my feeler gauges (actually I can't remember the last time I used them), so I used a similarly highly precise method of adjusting the doctor blade: I turned the screw a 1/4 turn, then made some copies. When it got too close the noise returned. When I got fairly close to the correct adjustment the arcing stopped, drum ground bars gone, and jitters crossfeed now gone. The drum is still trashed, and I'd really like to see a new developing unit in there.

Fifth call: Parts Available. Replace drum, again. The used replacement developing unit is worse that the first, so I stick with the first one now back in adjustment.

... and that's how an eS355 got three drums in three consecutive days, all because of a noise. =^..^=

[Luther]

It happened a lot on konicaminolta di350 series the rear spacer would wear and cause the same thing...how many copies on the effected machine?

[blackcat4866]

It's a refurb. 345K before the refurbish, 80K after, for a total of 425k. I've noticed that almost every 355/455 series machine makes this noise. Most techs assume it's the fuser, but if you touch the developing unit while it's cycling you can feel the vibration.

The customer tells me the new drums lasted almost an hour before being developer burned. I guess it's time to locate my feeler gauges. =^..^=

[ss12]

The rear spacer on the dev unit used to cause this issue as well

[Hansoon]

tech #1 widens the doctor blade gap (significantly). Now the mag brush is nearly twice as high at the rear, same affect

Pardon me please, you call that a "Tech"??

Hans

[allan]

You call that guy a tweaker. I always check the doctor gap of good machines with 80gsm paper like some ricoh machies would be 7 sheets of paper for a proper gap.