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Originally posted by ev607797:
I wouldn't waste too much time with examining the backplane. True, it's possible that a wire wrap connection may have broken, but I've never seen that happen on a 601. Then again, who knows what may have happened in shipping? That was one of the reasons for my last suggestion with reversing the ring voltage vs: 10 volt signaling.

I doubt that it's contacts either. Those card contacts are huge, so there's little likelihood that they aren't at least making partial contact. True, a relay contact could be bad. Since it's a matrix of relays, all it takes is one to mess up everything.

I guess it's best to go ahead and wait for the unit that Sam is sending. I hate to give up since I've never seen one of these things fail, but there is a first time for everything. Maybe that's why it was sold on e-bay!
Yeah, I have to agree. We gave it everything we had... the only other thing I can think of is if there is another home enthusiast with this setup, I could ship them the card and see if it behaves or not. But that's a bit of overkill, I'm Sure Sam's card will do the trick.

Thanks for all the tips everyone! I'll post back after I install Sam's card.