Finding shorts in boards

[Tony Duell]

> 
> 
> 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 :-(

10 Ohms is not a short! It might even be the right resistance. Have you 
tried powering it up?

> 
> 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.?)

Most times something shorts (particulalrly a decoupling capacitor) it 
goes dead short (<< 1 ohm). 

-tony