For this discussion, click here:
http://www.music-electronics-forum.com/t12368/the second response has 4 thumbnails and the schematic which I am asking about is the first thumb (Ampeg BA115/BA210)
1. My brother is troubleshooting this amp. The Test Note. Indicates that you inject a 170mV signal into the 0 dB input.
Test Point 1 (TP1), seems to be incorrectly placed. It indicates that he should see 700mVRMS on pin 3 of the TLO-72. However, at that point I am not sure where the gain is coming from? We believe this is a schematic error and TP1 should be post OP-amp (at PIN 1 of the TLO-72). Wouldn't that make more sense? (mind you, we both fool with tube amps regularly and solid state is befuddling to both of us).
2. He has a HP209 (I think) which he says only gives him (at lowest) a 1 volt sine wave. If we need to get a 170mV sine wave, is there any reason you could not build a voltage divider between the output and the amp (simple pot should do, right?)
3. What is the function of D10 and D13 (diodes from the input to the rails)?
Thanks... We are learning solid state by asking questions....
Thanks
Tim