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Since this machine is obsolete, all the replacement parts have been used, so there may be some risk of installing defective parts, but since I've never seen this before I kinda doubt it.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? =^..^=
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Since this machine is obsolete, all the replacement parts have been used, so there may be some risk of installing defective parts, but since I've never seen this before I kinda doubt it.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? =^..^=
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