Re: Messed up my Black Widow

I think that because the board has what appears to be a direct short, we won't see any potential difference at any of the nodes. But as Rodger pointed out, whatever part is responsible for shorting out the board, has a good chance that it's getting hotter than all the rest, and it should show up either with a non contact thermal infrared thermometer, or using the method he described. You could probably use a video camera in "night vision" mode to view the infra red signature, but there might not be enough dynamic range to tell the difference between the shorted part running hot vs. the other parts. It's just something you'd have to try. At least the non contact thermal infrared thermometers are a commodity, and can be had for short money.

Joel

On Jul 1, 2012, at 11:24 PM, Christopher X. Candreva wrote:

> On Sun, 1 Jul 2012, Joel Rosenzweig wrote:
>
>> You could have an integrated circuit that has failed, causing the short.
>> I've had failures with the TL082's (for example) that took the whole board
>> down due to an internal short. These are very tricky to find. I don't know
>> how to effectively troubleshoot that without removing parts one at a time
>> (or at least lifting the Vcc leg).
>
> I wonder if it would be possible to do a nodal analysis ?
>
> For those who didn't take (or forgot) circuits 101, this involes simply
> measuring the voltages at various points in the circuit (called nodes, hence
> the name). I remember years ago fixing a WG color vector monitor, because
> Atari printed nodal voltages on the schematics (probably exactly for this
> purpose). With the help of people on this list I was able to determine where
> my boards voltages differed from the schematic, and what was the likely
> failure based on this.
>
> So the first quesion would be, do the Black Widow (Gravitar) schematics have
> nodal voltages on them anywhere that would be usefull ?
>
>
> ==========================================================
> Chris Candreva -- chris@westnet.com -- (914) 948-3162
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Received on Sun Jul 1 23:47:37 2012