I own a vintage RCA audio premp (BA-72A). I bought this as a module some time ago and it quit working on me for some reason. So it did work ok for quite a long time but not now. I get nothing out of it. Here are the schematics I have: http://imgur.com/OOuqhNP http://imgur.com/GIsxqAT I'm trying to use this as a "6 foot deep end of the pool" learning experience as I'm studying electronics on my own and I've been trying very hard to understand the basics and stuff: transistors (depletion region... yep got it), caps (capacitance in farads which is work per volt) etc. I'm doing the work, I'm doing the math, and I'm pushing thru and hopefully getting it. But I seem to be completely lost when it comes to this spaghetti circuit?? I thought I could get some helpful guidance from some of you genius folk out there as I know there are very knowledgeable people here and I learn a lot every time I merely lurk over a post. This RCA preamp is apparently a 4 transistor preamp (2 stage input and 2 stage output) which has (in addition) a transformer on the input and the output. I've got a 700ohm resistor on the output transistor output to satisfy load requirements. I'm running the input using my computer soundcard with a 440hz wave or something. The power source (DC) is an actual RCA power supply used with this module and is giving a clean -30v-0v. ---------------------------- So now here's what it's doing: Zero. No output. I've got the input ac audio signal coming in on pin E1 via the transformer (and e2 is ground for that signal). I've got a good -30v dc attached. I've pulled off one leg of a few of the resistors involved in the first stage to test them and they're ok. I've pulled the first transistor and it checks ok with simple multimeter test (inconclusive). Out of the collector of Q1 I get a little of the positive high peaks of the input signal. Now I've "studied" the circuit (as much as I can with my limited knowledge) and I just don't see the input being biased up into the working range of the first transistor (Q1). So I'm guessing that it's only going to deal with the upper audio wave portion in the first transistor??. I've tried modeling the first half stage with falstad's wonderful ciruit designer java applet: (copy and paste/use the below link for the falstad model): http://www.falstad.com/circuit/#$+1...125E-4+0+-1 o+26+64+0+35+40.0+7.8125E-4+1+-1 And I just don't get it. It's apparently not biasing the initial transistor. I guess I'm just not sure what I'm looking at. I mean... why so many connections??? Sorry so long guys, and thanks for any "duh" epiphanies you can give me. Hopefully I'm getting over some hurdles with this stuff with your help!!