Output amplifier in older broadcast console
Posted: Sun Sep 22, 2013 1:11 am
Not sure if I'm posting in correct area, so here goes...
I have a Harris Stereo 80 broadcast console, from the late seventies area, and I'm trying to feel my way around learning about it. I have two amplifier modules (Left Program, Left Monitor) that somehow "smoked" (little whiff of white smoke and only visible sign of damage I see is a burnt resistor coming off a leg of a transistor mounted to a large heat sink). Units have I believe three feeds to them of 45vdc. Without module, I read voltages fine on connectors, but even putting bad module back in and trying to "learn" by testing areas for voltage, I'm finding voltages of 3vdc or less. Even at the feeds from the connector! Is whatever that is bad in the module causing the input voltages to be reduced? And any ideas on how this "jackleg" might try and find the culprit and repair? I do have the schematics and have been studying them all I can, trying to gain some kind of understanding...
If anyone is interested, there is a PDF file easily attained on the net, googling "Harris Stereo 80"...
Thanks so much for any help.
Tim
I have a Harris Stereo 80 broadcast console, from the late seventies area, and I'm trying to feel my way around learning about it. I have two amplifier modules (Left Program, Left Monitor) that somehow "smoked" (little whiff of white smoke and only visible sign of damage I see is a burnt resistor coming off a leg of a transistor mounted to a large heat sink). Units have I believe three feeds to them of 45vdc. Without module, I read voltages fine on connectors, but even putting bad module back in and trying to "learn" by testing areas for voltage, I'm finding voltages of 3vdc or less. Even at the feeds from the connector! Is whatever that is bad in the module causing the input voltages to be reduced? And any ideas on how this "jackleg" might try and find the culprit and repair? I do have the schematics and have been studying them all I can, trying to gain some kind of understanding...
If anyone is interested, there is a PDF file easily attained on the net, googling "Harris Stereo 80"...
Thanks so much for any help.
Tim