Finding shorts in boards

From: Jules Richardson <julesrichardsonuk_at_yahoo.co.uk>
Date: Wed Dec 1 07:21:30 2004

I've got a board here with a short between ground and the +5V rail
(actually not quite dead - I'm getting around 10 ohms between the rails)

Any useful tips for finding the fault? It's a large board, multi-layer,
lots of silicon on it unfortunately :-(

Are there any particular components that are likely to fail in this way
that might be found across PSU rails? (decoupling caps, certain ICs,
crystal modules etc.?)

Given a suitably sensitive meter is it sensible to assume I can try and
home in on the short location a little? (I've found readings between
GND/supply on various LS chips of anything between 9.5 and 12 ohms so
far)

I've checked the board for particles of anything that might be causing
the problem, plus I'm halfway through ruling out any of the socketed
ICs. Of course if it's a problem with the multi-layer PCB itself... eek!
(do these ever fail in such a way though? It's a commercial board which
used to be fine)

cheers

Jules
Received on Wed Dec 01 2004 - 07:21:30 GMT