Re: Vcc buss rails being pulled down.

I used to do something similar, you cool the board (or part of it) with co2
or freeze mist, enough to frost the parts over a little bit, apply power and
see what defrosts first .
On Oct 16, 2011 5:18 PM, "Chris Brooks" <armis@pcdochouston.com> wrote:

> Short of breaking out a milliohm meter, when I worked for a printer
> manufacturer and we had boards that had hidden shorts, we would use a sheet
> of temperature sensitive liquid crystal ( I think you can get sets of these
> from Edmund scientific still). Set the board on the bench, lay the sheet of
> liquid crystal over it, and connect the board to a variable dc supply.
> Slowly bring the voltage up. And the heat near the problem area will make
> the sheet change color. Was a pretty ingenious method my boss taught me.
>
> On Oct 16, 2011, at 4:38 PM, litterbox99@mchsi.com wrote:
>
> > I'm working on a Slot machine MPU, with
> > similar 74xxx components like our arcade
> > games.
> >
> > The Vcc buss is being pulled down to about 50mv.
> > The LM340T5 runs very warm, so were keeping the
> > power on time very low.
> >
> >
> > Besides removing the IC's one at a time (and
> > of course their not socketed ) is there a way
> > to ID which component is at fault ?
> >
> > We've removed the IC's that are socketed, and
> > checked for warm or hot components.
> >
> >
> > Todd
> >
> >
> >
> >
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Received on Sun Oct 16 18:23:14 2011