Re: Vcc buss rails being pulled down.

The only reason I didn't suggest this earlier he is that 50 mohms is a
pretty good short and you won't get much heat out of applying power do that.
On Oct 16, 2011 5:23 PM, "Rodger Boots" <rlboots2@gmail.com> wrote:

> 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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>

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Received on Sun Oct 16 18:26:04 2011