Re: Caps a poppin!

[Charlie Springer <RAM@regnirps.com>]

On Sat, 6 Jan 2007 19:09:22 -0800, Tristan Mumford wrote
(in article <45a06488$0$38170$c30e37c6@lon-reader.news.telstra.net>):

> I patched up an adaptor for an XT powersupply to test it. Still get the
> pretty patterns. Only it's a different pattern now. It's a more complete
> hatching of the screen with the occasional repeated anomaly.
> The RAM expansion still has it's write light on. Not sure if that's a bad
> thing.
> 
> I watched the hatch pattern for a while and noticed it changes a little.
> Every so often one of the irregular blocks disappears.
> My guess is it's either corrupt RAM changing states, or the CPU doing a
> turing machine through the mangled memory map.

Check the bottom (and top) of the board for any evaporated traces. Whatever 
blew up the caps could probably have blown up a trace as well. I find a great 
majority of problems on all types of boards by inspection under a stereo 
microscope. 

I got my first big ARM4 board that duplicates everything that a PC has from 
VLSI when they could not figure out what was wrong with it. Since it was 
free, I took it home. Close inspection showed a bent under pin on a ROM, in a 
socket yet! Fixed it and everything worked great.

-- Charlie Springer