NAD 3130 Amplifier-same fault 15 years apart!!

[Mark Hennessy]

Yes, I'd spotted them on the schematic. If I recall correctly, they are thermal breakers, so fairly slow to operate relative to how quickly the transistors might pop. Not really sure how effective they would be if the output was shorted while the amp was playing at high level. A more sophisticated amp would use VI limiting on each output transistor, usually instantaneous, but perhaps with a very short time constant built in.

Cheers,

Mark