Any experience with Tandberg Amps?

Before you hook it up and turn it on, you may want to bring it to a qualified tech to power it up on a Variac and check/replace any capacitors that may have dried out over time (they last 10-15 years or so). Just my 2 cents worth. Happy Listening on a great find.

Probably just a bad cap in the power supply, but you could have caused more damage on power up (the Variac takes it up gradually, and you can sometimes "reform" older capacitors). Very likely, your circuit protectors did their job, and there is little to worry. Just bring it to a qualified tech (see if you can find schematics online) and have it checked out. Your probably looking at $150 to $200. You will still be way ahead so don't fret.