Mtx ta92001 distorted output.

[Perry Babin]

It definitely shouldn't be shorted across all 3 terminals.

Is that what changed after you lifted D402?

 

[kfx5050]

If R4011 is within tolerance and there are no bad solder connections, you should have audio passing through to pin 3.

Lift D402 and see if anything changes.

D402 is lifted. Still have audio on one side but not the other. If I don't power the amp up no 12v connected. Or remote or ground. I have sound on both side of r4011. .

Im not shore when they got shorted. But they have been getting hot for a well now.

 

[kfx5050]

It's mainly the one on the top. Closest to the heatsink that's showing short and is getting hot when the amp is power up.

 

[kfx5050]

What part number do you have for those two?

 

[Perry Babin]

See attached.

 

[kfx5050]

I will pick some up to tomorrow.

 

[kfx5050]

Where does the middle pin go on the top mosfet ( closest to the heat sink) the pad left with the mosfet

 

[Perry Babin]

The collector of the PZTA56 goes to the negative low-voltage power supply. It's the same supply that feeds the op-amps.

 

[kfx5050]

Is there anything I need to watch out for be for installing the new PZTA56.

 

[Perry Babin]

I'd leave them out for now. Until we get a good signal out of the last op-amp, they can't be used. All they do is drive the optocouplers.

 

[kfx5050]

Ok. I have sound on both side of R4011. But I remove the ne5534 that's close to the heat sink. Does this point to a issue with this op-amp?

 

[Perry Babin]

The non-inverting input shouldn't affect the signal. If it is, the 5534 could be defective.

 

[kfx5050]

I have audio on both side or r4011 with out the ne5534 by the heat sink in. I replace it with a new one. For some reason it's doesn't make it on the other side of r4011 when the ne5534 are in or when there is power and ground connected to the amp.

 

[kfx5050]

Should led400 still be able to light up with r4111 missing and the two transistors and ne5534?

 

[Perry Babin]

When did it stop coming on?

 

[kfx5050]

It didn't. just asking.

 

[kfx5050]

The large resistor that was getting hot that was melting off how many volts are supposed to be flowning to that resistor?

 

[Perry Babin]

I think it has the positive rail voltage across it. It's not quite that simple but that's essentially the voltage across it.

 

[kfx5050]

Is is safe to power the amp on with no opt-couplers install?

 

[Perry Babin]

If the outputs are in the circuit, you have to short terminals 5, 6, 7 together.

Why are you taking them out?