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]

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]

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]

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]

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]

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!!!

 

[Perry Babin]

8.66k It's the same as R104.

What is the circuit board designation for the caps?

 

[nonprof]

8.66k It's the same as R104.

What is the circuit board designation for the caps?

Im sorry I forgot the number, it's beside the 4 DIP FET drivers, beside 2 output inductor, the other one I guess 2200uF/35V, do you think they must similar? the other one installed is just 10uF/35V.

I have some DLS schematics, in case somebody ask your help.

 

[Perry Babin]

C408 is 1000uF@35v.

 

[nonprof]

C408 is 1000uF@35v.

Thanks! I replaced the other one.

 

[nonprof]

Hello guys!

I need your idea for this amp. why the fans didn't turn on upon power-up? is there any thermal turn on after reaching specified temp? I notice that after I remove the remote supply the fan turn on for about few seconds? its weird!

kindly help me which component on this amp manipulated these fans. thank you in advance! more power!

 

[Perry Babin]

They are controlled by the signal level as well as by temperature. If you drive the amp to hard clipping, they should spin up. If you heat one of the various thermistors (like the one in the center of the transformer), the fans should switch on.

 

[nonprof]

Thank you Perry!

 

[nonprof]

8.66k It's the same as R104.

What is the circuit board designation for the caps?

how about the R106, didnt found 8.66k. 9.1 and 8.2 are available in the market. And physically R104 reads as 9.1k from the board.

 

[Perry Babin]

8.66k is a standard 1% tolerance resistor.

Use THIS image for the values. View full size (zoom in) to see the best detail.