Mtx Amp 100

I recently acquired an MTX AMP 100 subwoofer and it has a loud buzzing sound when powered up. Does anyone know where I could get a schematic and possible trouble-shooting help with this. The circuit board is labeled SUNBOW SP-600.

Any help would be greatly appreciated.
I just got one to fix with the same problem, I need to know the value of Di04, and Di03, I will share infomation as I progress.Thanks

I know this is an old post, but I am dealing with the same power amp myself.

D103 / D104 are Zener diodes P/N 1N4744a which is a 15 volt, 1 watt. They seem to run very hot as my board is roasted in this area. The resistors next door are 1.7K.

Any luck with your unit? Mine had roasted PS caps, power amp is coming up, but only have audio briefly when the power supply drains off. So I am looking in the same area and at the preamp stage.
Follow up question...

I had the same issue. There are 2 things to check for...either a ground loop in the circuit that you are plugging into, or , (my issue), check for swollen capacitors on the board. I replaced my capacitors and it sounded awesome after! Hope this helps

Sorry to dredge up such an old post, but believe it or not this is the only mention I could find of anyone working on this particular board. I appear also to have swollen caps, and my rectifier area is also “roasted” 🤣.

My amp started doing this weird “PANG” noise when turned on and then super rattley when attempting to play sound (it does still somewhat play sound). This is what prompted me to take a look at its guts.

Will I be good just replacing the bad caps or should I replace those resistors and diodes while I’m at it? (This is a question from a weekend soldering iron warrior and by no means a regular!)