Help! 7075 with random light copies!

[mrwho]

Could someone please help me here?

I'm trying to find out what's causing a Konica 7075 to output light copies randomly (by "randomly", I mean that, when taking 5 copies, the order could be: good, good, light, good, light; and a light copy can mean "completely light" or just "partially light").

If this wasn't odd enough, the machine only does it when working with A4 paper - if you put the paper on the A4R position, the problem goes away.

I've ruled out everything I could think of: drum ground, charge and transfer corona's and their respective HV boards and door switches.

Any suggestions? Thanks!

[SmellsHot]

does it do this when doing internal prints?

[mrwho]

Yep. And sorry for not posting more, since at the end of the day I think I figured it out, but I was so tired and sick of that machine I went straight home.

The problem probably was that someone had messed with the high voltages before, so they were completely out of target. I did restore the factory adjustments, and the problem almost (almost!) went away.

What does that mean? That most of the tests I did before (namely the transfer corona) need to be done again, since the first time the HV values were wrong.

Thanks for the reply. I'll keep you posted.

Cheers!