Stefan, This one you will appreciate - please read.
I was looking over the PCB for the printer trying to find the opto
and the triac. I am studying it like crazy - components on one
side, traces on back side trying to figure it out. It's not a dense
board by any means, I am just stupid. Anyway, to figure out what is
what, I would go to mouser and digikey and type in the part numbers
of the various components - didn't help at all.
So, while just staring at the PCB I noticed something interesting in
the legends - the board is divided into two sections -primary and
secondary. There are three, 4 pin DIPs bridging that outline and
one big transformer. After thinking about that for a moment, I
realized that those 3 small ICs are going to be the optos which
isolate the primary from the secondary !
Kinda neat how HP laid out the board like that. I will try to get a
photo of it.
chris
--- In
Homebrew_PCBs@yahoogroups.com, "Stefan Trethan"
<stefan_trethan@g...> wrote:
>
> On Fri, 02 Dec 2005 19:40:20 +0100, lcdpublishing
> <lcdpublishing@y...> wrote:
>
> >
> >
> > BTW, is this isolator needed for the same reason I needed one on
my
> >
> > spindle driver that fried my computer last year?
>
>
> Yea, more or less. it isolated the thermisotor and pot and supply
from
> mains, which isn't all designed to be at that
potential, 'specially the
> thermistor. Often it will be a phototriac which does the firing of
the
> triac the right way without hassle at a zero crossing.
>
> ST
>