Re: Messed up my Black Widow

A good ESR meter can be used with this method too as it sends 100 kHz through the "test path" it is much more sensitive than a regular DVM.

Verstuurd vanaf mijn iPad

Op 2 jul. 2012 om 05:57 heeft Rodger Boots <rlboots2@gmail.com> het volgende geschreven:

> 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
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Received on Mon Jul 2 02:34:06 2012