e Studio 2500C strange image quality issue

[blackcat4866]

Ok, I've got a pretty strange one today:
If I do 100 B&W monochrome prints or copies they look normal/fine. If I do more than ... let's say five color images, the black portion will fade mostly to blank. CMY are fine. My 11% LGR pattern and 15% LGR pattern produce the effect every time on the fifth and sixth page. It looks like loss of primary transfer or developer agitation. There is a shadow of an image and a few speckles of black, but just a faint outline.

Since this machine is obsolete, all the replacement parts have been used, so there may be some risk of installing defective parts, but since I've never seen this before I kinda doubt it. It's had drum unit, developing unit, primary transfer belt unit. I've investigated all these units closely, and the only real fault I found was some toner buildup on the black mag roller and the facing roller. It's very common and scuffs off nicely with the green scrubbie.

To me, the only things that really make sense are developing drive and HVT (primary transfer loss black only). I watched the developer drive from the rear and it continues to drive, even when the image quality fault appears. Maybe there's some problem with the drive coupler skipping ... but it makes no noise. Between each page the developer drive stops for a second, then reverses for an 1/8 turn, perhaps disengaging the coupler? The thing that makes the most sense is the HVT. There is more power draw on the HVT when all four colors are engaged, maybe causing it to partially shut down?

Has anyone seen anything like this? =^..^=

[clint@clintsimonsen.com]

Ok, I've got a pretty strange one today:
If I do 100 B&W monochrome prints or copies they look normal/fine. If I do more than ... let's say five color images, the black portion will fade mostly to blank. CMY are fine. My 11% LGR pattern and 15% LGR pattern produce the effect every time on the fifth and sixth page. It looks like loss of primary transfer or developer agitation. There is a shadow of an image and a few speckles of black, but just a faint outline.

Since this machine is obsolete, all the replacement parts have been used, so there may be some risk of installing defective parts, but since I've never seen this before I kinda doubt it. It's had drum unit, developing unit, primary transfer belt unit. I've investigated all these units closely, and the only real fault I found was some toner buildup on the black mag roller and the facing roller. It's very common and scuffs off nicely with the green scrubbie.

To me, the only things that really make sense are developing drive and HVT (primary transfer loss black only). I watched the developer drive from the rear and it continues to drive, even when the image quality fault appears. Maybe there's some problem with the drive coupler skipping ... but it makes no noise. Between each page the developer drive stops for a second, then reverses for an 1/8 turn, perhaps disengaging the coupler? The thing that makes the most sense is the HVT. There is more power draw on the HVT when all four colors are engaged, maybe causing it to partially shut down?

Has anyone seen anything like this? =^..^=

Check the development drive Assembly, either a lost tooth as when its driving the colour is operating differently to when just black

Sent from my F8331 using Tapatalk

[Vincent128]

weird...

does sound like a HVT issue, perhaps there is a capacitor on the HVT that is pooing out or one of the flybacks is failing.

[Blizzoo]

That's a bit strange. I'm thinking in case you have a faulty/broken 1st transfer case terminal 6LJ03220000 rear or 6LJ03319000 front that holds the 1st K transfer roller it may not spring back the roller correctly when pressure it's applied to the belt for color printing? I might be wrong but seen those case terminals crack and cause weird transfer problems. Once you are into the TBU also check if the K 1st transfer roller isn't deformed at the ends. As for the Dev Drive I believe there are some one-way gears there which may need a close look.

Any CA00's CE40's?

[blackcat4866]

That's a bit strange. I'm thinking in case you have a faulty/broken 1st transfer case terminal 6LJ03220000 rear or 6LJ03319000 front that holds the 1st K transfer roller it may not spring back the roller correctly when pressure it's applied to the belt for color printing? I might be wrong but seen those case terminals crack and cause weird transfer problems. Once you are into the TBU also check if the K 1st transfer roller isn't deformed at the ends. As for the Dev Drive I believe there are some one-way gears there which may need a close look.

Any CA00's CE40's?

Yup: CE40's. And the primary transfer terminals are OK (I've seen that before too). I even swapped them with cyan to see if anything would change.

The one-way gear 94T usually will pull registration jams E011 every time. The one-way gear 26T usually pulls a second transfer shift error CEC0. Both of these are in the registration assembly.

I agree with your reasoning. I wish that was the case. =^..^=