hi sorry i dont have a scope yet really wishi did im thinking the other ic has failed due to resistors heating up in the output side of the amp right next to the coils i dont know if the tl494cn ic has anything to do with the output since the amp comes on and stays on so im thiking the other ic has failed its an 8 pin ic next to the lm361n because when u hook up speakers to the amp i can hear a engine noise type thing on the outputs when tested on the bench which i think im hearing the op amp or preamp drivers working and i looked at the traces on the board where the come off that ic with no number on it and the resistors are inline with that ic
Did you ever get around to measuring the DC voltage on all of the pins of the 361?
Black lead on the ground terminal of the 361. Follow the trace away from the IC to find a point where you can easily touch your probe (where there is less of a chance of shorting to adjacent components).
Post a list instead a long line of text. Look up the datasheet if you don't know the pin layout (don't guess).
Pin 1:
Pin 2:
Pin 3:
Pin 4:
Pin 5:
Pin 6:
Pin 7:
Pin .....
It's time to buy a scope. Email me links to any that you're thinking about buying and I'll try to point you in the right direction.
Black lead on the ground terminal of the 361. Follow the trace away from the IC to find a point where you can easily touch your probe (where there is less of a chance of shorting to adjacent components).
Post a list instead a long line of text. Look up the datasheet if you don't know the pin layout (don't guess).
Pin 1:
Pin 2:
Pin 3:
Pin 4:
Pin 5:
Pin 6:
Pin 7:
Pin .....
It's time to buy a scope. Email me links to any that you're thinking about buying and I'll try to point you in the right direction.
Those voltages are close to what I'd expect to see (except for the missing negative signs for several pins).
When you drive a signal into the amp, is there any output?
Does the relay engage after the delay?
If you measure the DC voltage on the speaker terminals (one lead on a positive terminal, one lead on a negative terminal), how much DC is there?
When you drive a signal into the amp, is there any output?
Does the relay engage after the delay?
If you measure the DC voltage on the speaker terminals (one lead on a positive terminal, one lead on a negative terminal), how much DC is there?
hi just wondering if someone might be able to tell me where the op amps are located on this amp they are tl072cp but theres about 10 of them on the board theres 2 cards that stand up in the amp 1 for sub 1 and another for sub 2 theres 2 tlo72's on each board and on the main board theres like 7 or 8 of them wondering which ones i should replace to see if thats the problem with the amp since i have a alot of thoose tlo72's just laying around
You can buy/make a cheap low level (preamp) signal tracer by buying a Radio Shack Mini-Amp (277-1008) and the cables to fit the input.
You can generally check op-amps with a voltmeter. If the voltage on the inputs (inverting and non-inverting inputs, not power supply inputs) match (for each op-amp in the physical package) AND the op-amp has the proper supply voltage, the op-amp is usually OK. If the voltage on the op-amp's inputs don't match and the op-amp is being used only for local signals (virtually all preamp use) and is not part of a larger servo loop, the op-amp is typically defective (or there's a broken connection in the local feedback loop). There's no reason to start changing op-amps for no reason. If you learn how to check them now, you'll save yourself a lot of time in the future.
You can generally check op-amps with a voltmeter. If the voltage on the inputs (inverting and non-inverting inputs, not power supply inputs) match (for each op-amp in the physical package) AND the op-amp has the proper supply voltage, the op-amp is usually OK. If the voltage on the op-amp's inputs don't match and the op-amp is being used only for local signals (virtually all preamp use) and is not part of a larger servo loop, the op-amp is typically defective (or there's a broken connection in the local feedback loop). There's no reason to start changing op-amps for no reason. If you learn how to check them now, you'll save yourself a lot of time in the future.
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