"N_Cook" wrote in message
...
On 25/10/2015 08:00, DaveC wrote:
On 24 Oct 2015, Ian Field wrote
(in ):

That would be my guess - AFAICR: the laser discharges the static charge
on
the photoconductive film at the points where no toner should be
attracted
to.

I think a failed laser would result in a completely black page, maybe
the
transistor that drives the laser going leaky - but that's in a critical
constant current loop, a leaky transistor would probably destroy the
laser.

Any idea the approx voltage of the corona wire? I could check, but it
would
be nice to know if its 300, 600, 1000?

Thanks.


More like 2,000 to 5,000V. The generator is often a selfcontained unit off
28V or so, with just an on/off control line. Flop a 100M resistor to the
corona wire and insulated lead out to a neon bulb to frame , in the first
instance.

Pretty sure I've seen one at 6kV, most were somewhere around the 5kV mark.

Some older types are pretty sturdy and can give a nasty nip. Unlikely to be
as dangerous as microwave oven innards, but I still wouldn't bother sticking
my fingers in there!