Haunted Amp

[Menticol]

Hello!!

It's a dumb and offtopic question, but I can't figure out the answer. I'm trying to repair a very old and small Alpine 3531 car audio amplifier, before throwing it definetly to the trash bin.

In te middle of the night, when I realized the amp was totaled (Corroded PCB, broken tracks beyond repair), I removed the speakers, with the power supply and signal still connected.

What the hell!!! music was coming out of the board! I could not point the component causing it, I guess it was a group of capacitors. I have heard AC hum before, but AC-DC - Highway to Hell Hum is the strangest thing I ever heard!

What do you think guys?

 

[Roff]

Hello!!

It's a dumb and offtopic question, but I can't figure out the answer. I'm trying to repair a very old and small Alpine 3531 car audio amplifier, before throwing it definetly to the trash bin.

In te middle of the night, when I realized the amp was totaled (Corroded PCB, broken tracks beyond repair), I removed the speakers, with the power supply and signal still connected.

What the hell!!! music was coming out of the board! I could not point the component causing it, I guess it was a group of capacitors. I have heard AC hum before, but AC-DC - Highway to Hell Hum is the strangest thing I ever heard!

What do you think guys?

Disc capacitors will sometimes vibrate in response to the voltage across them. I have seen it in multivibrators. I suppose it could happen in an audio amp as well.

 

[Mikebits]

Were there transformers at the output?

 

[Leftyretro]

I'm sure it was a haunted amp and it's a good thing that you trashed it