Resurrecting this dead horse.
It seems to have an issue with the + rail monitor circuit. It consists of a 49V zener and a few transistors. It won't allow the relay to energize, so I get no output.
I can remove the relay and jumper the via's and the audio is produced on the output. The rails measure +-63V.
Any diagrams floating around on the monitor circuit.
It seems to have an issue with the + rail monitor circuit. It consists of a 49V zener and a few transistors. It won't allow the relay to energize, so I get no output.
I can remove the relay and jumper the via's and the audio is produced on the output. The rails measure +-63V.
Any diagrams floating around on the monitor circuit.
What I came up with for the rail led indication and relay turn on.
An externally hosted image should be here but it was not working when we last tested it.
The 47V zener in the -rail indication circuit was bad, the LED is lit when the rail voltage is to low. In this case the zener was bad causing the circuit to keep the LED on.
I also found Q1 a 7805 defective, this keeps the relay from energizing and you have no output. The rca's feed two resistors that flank the relay, you will see the input waveform on those two parts. It then feeds the N.O. contact of the relay, when the relay is energized the signal passes through.
I need a 7805 to finish this amp, will get that tomorrow and hope it completes this project.
I also found Q1 a 7805 defective, this keeps the relay from energizing and you have no output. The rca's feed two resistors that flank the relay, you will see the input waveform on those two parts. It then feeds the N.O. contact of the relay, when the relay is energized the signal passes through.
I need a 7805 to finish this amp, will get that tomorrow and hope it completes this project.
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