So, our sample TZ hasn't had a working clock for years and years. I've ordered a new board from rottendog, but decided to play with the old one in the meantime. It's interesting, because every single opto doesn't work. They're all getting power (around 13.5 volts), but darned if each and every one is unresponsive. They don't register as open in the switch test. I'm just curious what could be causing it. Looking at the schematic, they all seem to be pretty seperately wired. The board isn't even that fried, as the techs that came before me helpfully put in diodes to control the heat. Ideas, anyone?

Correct answer: Some idiot wired the switch column wire into the ground. I think the molex pin fell out, and they stuck it into the wrong end of the plug. Works quite nice now. But thanks for your help!