MTX Thunder TA92001

[nonprof]

Hello guys again...

I repairing this amp because it has no sound. Protect and thermal light does not come ON, no rail high voltages( but just around less than +-20V). And I found there's a lit on SMT LED besides 3120 opto couplers. what does this mean?

thank you so much!
-Armand

[Perry Babin]

That LED (LED400) means that the mute delay has ended and the switching circuit for the output drive has been enabled. This is lit normally.

[nonprof]

Originally Posted by Perry Babin

That LED (LED400) means that the mute delay has ended and the switching circuit for the output drive has been enabled. This is lit normally.

any idea why I think it is muted? first IC(3120) on left most heated much. idea please?

[Perry Babin]

It should have much higher rail voltage. Are you sure that the power supply is operating properly?

[nonprof]

Originally Posted by Perry Babin

It should have much higher rail voltage. Are you sure that the power supply is operating properly?

hello!!! rail voltages are +-20v only. PWM readings are these...

Do I have problem on pin 2? May I know what's the source of the protect?

1. 0.08
2. 0.09
3. 3.57
4. 1.037
5. 1.49
6. 3.36
7. 0.009
8. 13.37
9. 0.009
10. 0.004
11. 13.36
12. 13.76
13. 4.9
14. 4.9
15. 4.9
16. 0.005

[Perry Babin]

I would expect pin 2 to be higher.

It likely has a resistor (R106) connected between pin 2 and pin 14. If that's correct, confirm that that resistor is within tolerance and that there are no bad solder connections on it.

Also post the resistance from pin 2 to pin 7 (no power applied).

[nonprof]

Originally Posted by Perry Babin

I would expect pin 2 to be higher.

It likely has a resistor (R106) connected between pin 2 and pin 14. If that's correct, confirm that that resistor is within tolerance and that there are no bad solder connections on it.

Also post the resistance from pin 2 to pin 7 (no power applied).

You got it Perry! defective resistor R106. thank you! It powered now :-)

May I know what is the capacitance value of C410/C411? I burnt it:-(

Thanks again!

[Perry Babin]

I don't have the value for those. MTX will give you the values. I'd guess that they're 0.1uf@50v but confirm. I'm assuming that they're connected to pins 5 and 8 of the opto-couplers.

[nonprof]

Originally Posted by Perry Babin

I don't have the value for those. MTX will give you the values. I'd guess that they're 0.1uf@50v but confirm. I'm assuming that they're connected to pins 5 and 8 of the opto-couplers.

Yes they are connected. Thank you so much! this became a head ache to me, I sold this amp for just $250 but returned by the owner for repair.

[nonprof]

Originally Posted by nonprof

You got it Perry! defective resistor R106. thank you! It powered now :-)

May I know what is the capacitance value of C410/C411? I burnt it:-(

Thanks again!

Hello!

May I know what is the resistor value of R106? And kindly provide me the value of the +- power supply electrolytic capacitors for 8-pins DIP output FET driver?
Maybe other engineer partially replaced this capacitor for isolation purposes but forgot to replace with the original.

thanks!!!