I have interesting one today, got a basic Rockford fosgate with 45vdc on the speaker terminals. All the power supply FETs and audio FETs check out good. What I have found so far is there is little to no voltage on the P channel fets. Lm337 has little to no voltage.
I replaced the lm336 voltage regulator. I found no issues the in the driver circuits, could this be a drive signal issue? I know modulation is the tl494 for powersupply but does it modular for the audio too
I replaced the lm336 voltage regulator. I found no issues the in the driver circuits, could this be a drive signal issue? I know modulation is the tl494 for powersupply but does it modular for the audio too
DCV on RCA jack shields?
DCV on the positive and negative PS terminals of the various op-amps?
If you briefly touch a dummy load across the speaker terminals, does the 45v drain off or does that cause the amp to draw excessive current?
DCV on the positive and negative PS terminals of the various op-amps?
If you briefly touch a dummy load across the speaker terminals, does the 45v drain off or does that cause the amp to draw excessive current?
If I put a 2ohm load on terminal it draws current, rca shields to negative terminal have 0.7vdc and negative terminal to rca signal 8vdc
Shorted negative rectifier?
Shorted negative rail cap?
I'm assuming you mean -8v on pin 4 and 14v on pin 8 of the TL072.
Shorted negative rail cap?
I'm assuming you mean -8v on pin 4 and 14v on pin 8 of the TL072.
I will pull all the rail caps and lift the legs on the 1620r, I already checked the rectifier and rail caps near it along with replacing the lm337 voltage regulator
A short would be obvious in the circuit. An open negative rectifier is another possibility and lifting the terminals may be a good option.
Confirm that the negative speaker terminal reads 0 ohms to the primary ground.
Confirm that the negative speaker terminal reads 0 ohms to the primary ground.
Sorry for the delay Perry had to walk away after the element burned out of my hot air solder gun.
So it was the negative rectifier. I not sure why I was thinking the negative rectifier was beside the positive voltage regulator. Anyway I pulled the legs on it and it tested fine but when deadened it from the back I could see through the pin holes and thought that was odd. Turns out the center leg either broken off at top of the eyelet and solder joint broke. Once pressed the leg further down in the eyelet and resoldered it all voltages were back.
So it was the negative rectifier. I not sure why I was thinking the negative rectifier was beside the positive voltage regulator. Anyway I pulled the legs on it and it tested fine but when deadened it from the back I could see through the pin holes and thought that was odd. Turns out the center leg either broken off at top of the eyelet and solder joint broke. Once pressed the leg further down in the eyelet and resoldered it all voltages were back.
