Class T issues US Amps PT-800 rev.2

Hello guys

I have an Class T US Amps PT-800 rev.2.
Amp works but pushed a little bit harder and it cuts out audio output.

There is a green diode (in green circle) near the Tripath's chip , it goes off when the amp cuts its output. Power light stays on, no protection.

There are two potentiometers near the chip (in red). They have been messed around by the previous owner. What are these for and how to set them up correctly ?

I do not have the schematics and in owners manual there is nothing about those two potentiometers.

Any help would be greatly appreciated.
 

Attachments

  • 1.jpg
    1.jpg
    185 KB · Views: 100
  • 2.jpg
    2.jpg
    273.5 KB · Views: 97
The pots may be DC offset.

The diode may be the same as LED2 in the following diagram:
http://www.bcae1.com/temp/clarion - dpx1001.2.pdf

Yeah maybe they are DC offset.

LED2 at the provided diagram is for one ohm operation mode. My amp is not capable of driving one ohm loads.

My guess is that this green diode is for the operation of the Tripath chip itself. I draw my conclusion from when there is output it's light up, when the output is being cut off it goes off too.

And without schematics I can't trace and understand how the overcurrent protection works... I know in class D there are precise low ohm resistors but in class T... ?! 😕😕😕

PS:Oh sorry I forgot it's PIC controlled so there is no way i can rework the protection circuit...
 
Last edited:
Okay the datasheet for the TA0103A is going to take hours to read.
But if i'm being right there should resistors as these in my amp too. These are the overcurrent sensing resistors, aren't they ? 😕

But are these integrated in the chip itself or they are board mounted ?
 

Attachments

  • 1.JPG
    1.JPG
    275.2 KB · Views: 90
  • 2.JPG
    2.JPG
    125.7 KB · Views: 91