SAVIN 4022 background problem

[SPAWN]

Hello everybody out there!!

We have a customer with a Savin 4022, this machine was making background copies on both sides, we replaced the drum unit, the transfer roller, after that the machine was working fine, one month later the customer call for the same problem. I'm getting frustated
'cause I don't know what to do to fix this issue, I can't replaced the same parts, could it be the DC controller or the Bias PCB? does anybody had this problem before?

Any suggestion is welcome, appreciate your time to read my headache.

Respectfully

[rthonpm]

Is the customer using OEM toner? You may also want to check the fuser as well.

[frank.tw]

if i have background problem
i will change the developer first (especially for this series)
then the drum final is the transfer belt

[wyched]

have you checked the transfer roller cleaning blade ??
if you run 1 sided copies, and have background on the back side of page (the side not printed on ) your transfer roller cleaning blade may need replacing.
try cleaning the blade