I made some frequency tests this night.
I don't see any kind of oscillation. I do see some movement on the top part of the sine wave when it clips. There's a little wiggle on the clipped top side. but before clipping the sine is clean 20Hz-20kHz.
The output is fairly linear. I loose about 5-10% amplitude on the high end.
Also there's something strange happening past 22kHz. the sine becomes fuzzy from the top down, and as I sweep slowly the amplitude decreases until flat line, then goes up again and reaches full peak again at 23-24kHz and looks very good at 25kHz (as much as I could test for). Probably can do a bit more to 30kHz.
I don't know what is happening, seems like the signal is inverting when rising again past 22.5kHz.
I decided to crack open two burnt output MJE15032 transistors. I found two types at the store, both in the same box.
Is any of the two a fake? Or at least a decent copy/implementation? I could replace them all for one kind if there's one legit.
I will have to take both boards out again. The right channel to replace the 0.5ohm resistors that I burnt (and used the old ones from the amp), and the left channel I want to replace the driver transistors with 2sd669ac (which I don't think are legit as well)
2sd669 has a gain of 245 and 2sb649 has a gain of 270 (made with cheap dmm function). As I read the original had a lower 170ish or so. They do look nice as a product, not a cheap clone.