Re: Vcc buss rails being pulled down.

Remove the regulator.

Power the board's 5V rail directly from a current limited power supply.
Before connecting the power supply, set it for 5V, then turn down the
current limit to zero. Connect the board and crank up the current until
it's at 2 or 3 amps. All that current will go through the shorted element
and you should have no problems finding it.

Do you have a cheap small compass? Current flowing through traces generates
a magnetic field.

On the off chance that you have a small (TO-92) analog Hall sensor lying
around, you could use it as a current tracer.

William Boucher
http://www.biltronix.com

----- Original Message -----
From: <litterbox99@mchsi.com>
To: <vectorlist@vectorlist.org>
Sent: Sunday, October 16, 2011 7:01 PM
Subject: Re: VECTOR: Vcc buss rails being pulled down.

>I have an $85 thermal gun w/laser and we checked
> the IC's b4 the reg got too hot (140f) and the IC's
> were all nominal @ 70.0f +/- 1.0f.
>
> ----- Original Message -----
> From: "William Boucher" <wboucher6@cogeco.ca>
> To: vectorlist@vectorlist.org
> Sent: Sunday, October 16, 2011 4:33:49 PM GMT -06:00 Central America
> Subject: Re: VECTOR: Vcc buss rails being pulled down.
>
>
> Usually the shorted component gets warm, at least significantly warmer
> than
> the others (not counting the shorted regulator). You can use one of those
> handheld gun type infrared temperature measurement tools to see which chip
> is taking all of the current and heating up. It only takes an increase of
> couple of degrees to find it.
>
>
>
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Received on Mon Oct 17 07:51:02 2011