I'm stuck and a little help will be greatly appreciated. There is a negative 12vdc bias on the right channel. the diagram above is where the issue lies. With Q715 out of the circuit all voltages and transistor biases are correct. With it in the circuit the 12vdc results on the collector and therefore all the way through to the output transistors. It is not the transistor though as I have swapped left and right channel. All other transistors test good out of circuit and all base/emitter potentials are correct even when the error is showing. Likewise the difference across the two parts of the output resistor (0.47ohms) is correct also. R729 even has the same drop as it's mirror on left channel. (about 75vdc), the diode(s) between the collectors of Q711 and Q715 are good as well. C715 electrolytic is new and tests good. It appears to me that Q715 is passing too much of the collector voltage but the base emitter potential is 0.6vdc as spec'd. BTW the speaker relay circuit works as it should if the logic chip sees the proper 0vdc for both channels. with the -12vdc lurking it of course stays deactivated.
