There are 4 optos, one each for...
regulation
over-current protection
DC offset protection
mute delay
If the amp isn't in protect, it's not likely that the problem is an opto-coupler, especially if you have r-r oscillation.
Is your signal source grounded to the 12v power supply ground?
Is the 220 ohm resistor within tolerance?
I would expect to see signal on pins 1 and 7 of the op-amps directly behind the RCA jacks.
regulation
over-current protection
DC offset protection
mute delay
If the amp isn't in protect, it's not likely that the problem is an opto-coupler, especially if you have r-r oscillation.
Is your signal source grounded to the 12v power supply ground?
Is the 220 ohm resistor within tolerance?
I would expect to see signal on pins 1 and 7 of the op-amps directly behind the RCA jacks.
signal soure is grounded to the 12 volt supply..
The 220 resistor measures 218 ohms off the board..
1 of the op amps that sit directly behind the RCA jacks i get clean audio on pins 1 and 7
The other opamp tht sits directly behind the RCA jacks i have clean audio on PIN 7 but no audio on pin 1
Pin 1 of that opamp shows 14 volts on it .. i replaced it and same result
The 220 resistor measures 218 ohms off the board..
1 of the op amps that sit directly behind the RCA jacks i get clean audio on pins 1 and 7
The other opamp tht sits directly behind the RCA jacks i have clean audio on PIN 7 but no audio on pin 1
Pin 1 of that opamp shows 14 volts on it .. i replaced it and same result
If you connect a speaker and signal source and operate all switches and controls through their entire range, do you ever get any sound or noise out of the amp?
I don't have a diagram for the amp but either the master/slave or the input level switches could cause no audio (more likely the input level at this point in the circuit).
I don't have a diagram for the amp but either the master/slave or the input level switches could cause no audio (more likely the input level at this point in the circuit).
You don't have to replace switches to determine if they're defective. Move them to a position that you want to use and confirm that you read 0 ohms between the contacts that should be shorted internally in the switch. If you still have concerns or you confirm that the switch is defective in that position but want to continue troubleshooting other problems, solder a bridge between the terminals that should be shorted by the switch but are not due to defective/dirty contacts.
I don't have a diagram that matches to this amp so you will have to follow the signal through the amp to see where it becomes distorted.
Using a multimeter to check drive voltage is not the best method for testing. It's not definitive and typically only for those without a scope. If you have a question about the drive signal, post a scope cap of the drive waveform.
I don't have a diagram that matches to this amp so you will have to follow the signal through the amp to see where it becomes distorted.
Using a multimeter to check drive voltage is not the best method for testing. It's not definitive and typically only for those without a scope. If you have a question about the drive signal, post a scope cap of the drive waveform.
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