Hi, anyone had success in repairing a Class D subwoofer amplifier ?

I am working on a Class D module used in Alto's and other brand of sub and active speakers.
It's a Seikaku DM350W+65W.

I have about 2v of 344 khz sinewave when on, no DC at all.
But that jump to 1 Vdc once Off and drop slowly to zero in about 5 minutes.
Sound like a DC offset problem, but i do not understand the couple of feedback loops in this thing.

The power switching amp section is on page 3, but the linear signal line is on the b ottom of page 2.

Any idea ?

 

The low power amplifier is not a class-D amplifier. Your schematics page 2 shows an old TDA7294 class-AB amplifier that produces 65W at low distortion into 8 ohms when the supply is +35V and -35V. I guess it is for a sensitive horn tweeter and the 350W class-D amplifier is for the woofer.

The datasheet for the Driver IC night show how it works. You might not find a replacement IC.

 

Hi, yes the 65w amp is linear and is dedicated to mids or high.
In fact this IC and it's support components are not even installed on this subwoofer version of the board.

The audio drive IC IRS2092 seem to work since i have no DC when powered.
Just about 1v of 344 khz switching AC residual.

It's the DC that is appearing at power off that is bugging me.
I will load the line to see how much power is left at power off..

 

Here is the data sheet for the driver.
The suggested circuit is about the same as the final one of the amp.

Once loaded, i've tried 8 ohms, the DC disapear in 0.5 second.
But there is still a medium snapping noise at power off with a speaker.