Re: Messed up my Black Widow

I don't think all the modal voltages in the world are going to help if
power is shorter to ground.

What works great (used to do it at work), but requires a damn good
ohmmeter, is to find the most shorted point by measuring for it.

I had a HP 34401 meter at my station. You lock it into the lowest ohm
range and set it for 6-digit readings. Then enable min-max mode. Pick a
starting point on the board. Meter will beep because you found a low
reading. You then just walk your leads around looking for a lower
reading. The last point that beeped is where the short is.

But the frost-it-up method can be faster (I had a CO2 spayer available).

I wonder if when he pushed the chips back in if a socket lead didn't just
bend over on THE BACK SIDE of the board.
On Jul 1, 2012 10:24 PM, "Christopher X. Candreva" <chris@westnet.com>
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
> WestNet Internet Services of Westchester
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Received on Sun Jul 1 23:57:37 2012