asked Jan 24, 2001 at 2:11pm
Unknown Printer

QMS Magicolor 2 - blank pages

I've got a broken QMS Magicolor 2 color laser (Hitachi SL-1 engine).

It doesn't give any error messages, but all pages come out blank. Has anyone
experienced this problem with this engine?

Stopping the printer while it's printing shows that no image is ever formed
on the OPC belt. A small plastic box providing the electrical connections
to the belt contains a component (HV zener diode?) connecting the metallised
belt (also wired to HV PSU board) to the grid between the belt and the
corona wire (no other connections to this grid).

If I short this component out, the machine covers the whole page with toner,
so the image transfer from belt to drum to paper is working. Removing this
component gives blank pages again. Replacing it with a stack of zeners to
about 100V results in around 10\% toner coverage over the whole page with an
extremely faint image just visible.

Perhaps the HV to this component (and the belt) is too low? Any ideas about
possible failed components on the HV board? Other HV is working since toner
transfer to drum and paper is fine, and faint ozone smell is present.

The unidentified component has a normal diode I-V characteristic tested up
to a couple of volts. It's in a square plastic case with a '+' marked on the
wrong leg for a normal diode (correct for a reverse biased zener).

Any suggestions for what the problem may be? Many thanks for your help!