Matt, On Buss 1, we do not get output. When we patch any other buss 2-8 to a > channel everything is cool. When we patch buss 1 we get no signal, but > we can hear the level changing as we turn the pot back and forth. We > traced the output (which we are assuming is the bottom of the card) > back to the resistor tied to the 7 pin of the TL074, and we do not get > a voltage there. On all other busses we do. We changed out the chip > and the problem persists. We pulled out that resistor and it's > neighbor and they measure okay.
I'm a little confused by the "we can hear the level changing" bit. The output of buss 1 are pins 21 (signal) and 22 (ground) at the bottom of the card. 1. Does anybody have a scan of the schematic for the buss master card? Yes, and I'll send one to you if you forward you email address to me at [email protected]. Though there might be some subtle changes depending on mfg. date, my guess is that they're all pretty close to one another as far as circuit design is concerned. 2. Does anybody have any idea what to look for? Are you getting + (pin 4) and - (pin 11) power to the TL074? Cheers, -- Don
