C500 Bizhub White Spots

[Oscar57]

Hi,

I'm having a problem when I run Offset stock. I do not have this problem when I run Coated stock. Finch digital opaque a good quality sheet. It seems that paper dust may be the cause. But I'd like to get some opinions. I get low density spots that appear white with the naked eye but with a loop you can see that the spot has color screens in it but at a lower density. I've tryed different toner refresh rates but that hasn't helped. After the spots appear if I run a coated job the spots quickly disappear. Any suggestions would be appreciated!

[nmfaxman]

Try reducing transfer voltage a little bit.
I have seen this in high altitude, low humidity areas.
I call them fireflys.

[Guest]

I would experiment with media type/paper type settings...

[Oscar57]

I tryed increasing transfer voltage and it didn't help. On monday I'll try reducing the transfer voltage a little as you suggested.

[jprecht]

snowflakes

agree with previous post try reducing the charge. i have to wonder if you are using "top shelf" stock if you have to use a loop 2 see this prob. has 2 be a stock/heat/humidity issue. you say it clears up on "coated stock"? how many hits you running on the finch does (snowflakes) appear right away? this box is very forgiving on a wide range of stock 2 my experience. have you experimented with fuser settings? what a FUN problem!!!
let us know what you find!!!
JP

[Oscar57]

It takes 400-500 12x18 single sided sheets for the spots to start showing up. Then it gets worse as the run goes on.

[nmfaxman]

Transfer arcing causes lack of transfer because there is no voltage in the area to pull the toner from the drum.
Stop the paper midway and check the drums.
No charge causes dark spots.
No transfer causes light spots.
Paper dust in a DV unit causes white lines.
Paper dust in a cleaning blade causes dark lines.

Basic physics on how a copier works. KISS it. (Keep It Simple Stupid)
As soon as you think you need a new board, take a break then go back and look at the problem with fresh eyes.

[jprecht]

kiss it

Faxman is probably right if it takes 400-500 shots b4 the degradation begins your currents/insulators r suffering. it's amazing how quik custs "pick up on a prob like this" very interesting you are NOT seeing this on "coated stock", if u turned up your current as u said would have gotten worse sooner. normally u would target your "sep" as the culprit, although i have seen "cleaning issues" in the fusing process acct for "snowflakes" usually bcuz of "lint factors" let us know and happy hunting!!!
jp
let the wkn'd begin happy 4'th to all!!!