Pioneer SX-6 Mute Problem

[antiquekid3]

Hey guys,

This SX-6 belonged to my mom back in the 1980s, I presume. We have since replaced it with a new Onkyo just because it was old. Since my parents let me keep it, I have used it for a few "experiments," one of which was driving some LEDs to make a mechanical television about two years ago. As I was experimenting, I had to turn up the volume way up in order to get the high intensity LEDs to light up. I wanted to turn off the LEDs just for a second, so I pressed the mute button. The LEDs went dark, but then...smoke started coming out the top of the amp and the LEDs started getting brighter and brighter until the unit was not muted anymore. I quickly turned it off after seeing (and smelling) the smoke.

It still seems to sound just fine (when using it as a normal amp, and hence I haven't really worried about fixing it until now). It just won't mute anymore. So...most likely, what did I blow? Where should I start to look?

BTW, I am constructing an ST-70 right now and will definitely post some pictures when I am done. However, I have to locate two more A470s since mine were blown when I got the amp.

Thanks!

Kyle