All right, I've done a more thorough inspection of both logic boards, and there doesn't seem to be any visual evidence of capacitor leakage... though I know there's no foolproof way to tell a bad cap other than to remove it and throw it in a tester.

I did some very light cleaning with rubbing alcohol and a sponge-tip brush, and cleaned all the contacts and re-seated the ROM and the RAM SIMMS in both machines. Made no difference whatsoever. The batteries in both machines are dead, and I do need to get replacements for those. As stated before, one machine has sound but the display is "pinstriped" with missing columns of pixels, and the other machine displays properly but has no sound. I have tried both logic boards with each display assembly, and the problem is definitely with the logic board.

None of the graphics glitch guides really list a problem quite like this one, so I took a picture. Sorry about the low quality; the only camera handy was the webcam built into my laptop:



I can live with the one computer not having sound, but this screen issue really makes it difficult to even use the other.

Once again:

Computer 1: Mac SE/30 with 40MB hard drive, 8 MB RAM (8x 1MB SIMMS), System 7.5; sound works, display is pinstriped

Computer 2: Mac SE/30 with 160MB hard drive (dead), unknown RAM (4x 1MB(?) SIMMS); sound does NOT work, display works

Both have dead batteries, and neither have evidence of capacitor leakage.