How not to fix a classic mac (or: fried logic boards)

The other day I picked up a Macintosh 512k with a broken monitor for $5 thinking that it'd be a fun project to hack on (yes, another thing to add to my pile of things to hack on, just what I need :)). The power/sweep board had a couple of obviously dead capacitors and a few cracked solder joints, which I fixed up and lo and behold, the screen came back to life and I did a little dance. There was still a bit of jitter in the picture from time to time, and jiggling one of the connectors revealed another dry joint so I powered it down and prepared to fix the other joint. First point of business, I discharged the CRT. To the main chassis. This, as I have now discovered, is not what you are supposed to do to discharge the CRT unless you want to destroy the logic board. I now have a working monitor but a fried logic board; on powerup, the normally short boot tone is long and drawn out, as if the machine were running at a tiny fraction of its normal speed. Which I suppose is actually what's going on. So I killed _something_ on the main PCB, but I'm not sure what. Anyone out there experienced this failure mode? Any obvious things to check? Well, live and learn. At least it wasn't a 128K mac :). Thanks, Josh