"robb" wrote in message
...

"Tom2000" wrote in message
...
On Tue, 6 Nov 2007 07:34:53 -0500, "robb"
wrote:



there was no obvious visual evidence of any smoked parts that
i
could see , only the middle busman fuse was blown after the
short

and that seemed to be related to power going to the L298

thanks for all the help,
robb


Tough problem with all the ICs soldered in.

Chances are that the 32 volt supply is only used for the L298s,
as you
suggest. It also appears that you can unsolder these without
damaging
any other parts on the board. (Even if you have to cut them
out,
they're still available and easy to replace.)

If your short doesn't disappear after pulling the 298s, try
unsoldering any of the caps near those chips.

Leave unsoldering any ICs as your very last resort.

I'm now bowing out of this discussion and leaving it to the
experts.


Thanks Tom,
i really appreciate any comments and help

i unsoldered one of the L298 and it has no shorts so now the next
then i will do a trace of the 5V lines until i can learn
something usefull about the interconnections.

i hate working blind and re-tracing things when i could just look
on a schemat.

so thank you ,
robb



While normally a very bad idea, a trick I've used with success once or twice
was to bypass the fuse and feed a few volts with reasonably high current
capability into the thing while feeling what gets hot. This needs to be used
with great care though, you can burn traces off the board or in some cases
do further damage, but if 32V got put into the 5V rail, you've got little to
lose in trying.