OT laser printer question

[Tony Duell]

> If its the physical letters on the paper, if they are lumpy or if they 
> are smearing if touched then your High Voltage power supply board is 
> starting to fail.

Can you be a little more specific? What is the _real_ cause of the problem?

Intuitively, if the toner smears when touched, I'd assume it wasn't being 
fused properly, and would investigate the fuser and its control system 
first. How does a problem with the HV supply cause this fault?

Getting back to the HV system, I know that in my SX (and I think in 
the CX before it) printer, there's an AC 'ripple' applied to the high 
voltage on the toner reservoir that causes the toner to come on and off 
the drum slightly, and thus improve the evenness of distribution. Maybe 
if that was malfunctioning it would cause this sort of problem.

Alas I only have (my own) schematics and notes for the CX and SX 
engines, nothing later, so I can't really comment.

-tony