hey guys.
i have a short somewhere comes and goes as it pleases
i kept blowing the fuse for the ignition switch in the engine bay so
what i did was i fused one just so i can locate the short somewhere.
but the jokey thing about it is that sometimes it starts and sometimes
it doesn't.

it started out of no where, car was running fine all month and one day
at the mechanic shop we pulled it in to fix the master brake cylinder
and once we fixed it we went to start it and we blew the fuse.  so we
replaced it fine and it worked for a bit and than it kept blowing so we
fused it and it worked fine again for a while and than it shorted
again, but this time when it shorted it blew the black/wire ignition
wire on the ignition lock off of the solder.  we re-soldered it back
and it worked fine for a bit and now when it shorts the wire gets hot
and it comes off the solder on the ignition lock.

can someone inform me some instructions on what can be causing the
short?? i'm thinking the ignition relay, but i have no idea where the
igition relay is.  or is there any other relay that i should be looking
at as well.

its an 89 240sx coupe 5spd, canadian version.   meaning there isn't a
clutch bypass, i can start the car in gear and without the clutch being
depressed.

thanks in advanced, any help would be appriciated.
thanks.