Smoke on my power amp

first .... there is nothing wrong to run an amp without speakers or only one channel. but disconnect speaker cables from the amp terminals to prevent  speaker wires   accidental short... most new amps has adequate protection , but vintage ones   do not survive .
so you got 2 possibilities... one is the other ends of speaker cables touched each other . or   just bad luck and amp  got fried with no reason whats so ever . now, can you turn on the amp ?preferably not... for one reason  ...to help a repair man. when he opens the unit and turn it on hopefully  the defective part still smokes  and he can easily determine the problem. but  if you continue to press power button the part eventually would stop smoking and if there is no   easily noticeable burn mark  troubleshooting is more  difficult .

My bad.
https://www.flickr.com/photos/186572523@N06/49415455691/in/dateposted-public/
https://www.flickr.com/photos/186572523@N06/49415663367/in/dateposted-public/

I have not turned it on again since the smoke.
I am trying to find which repair shop to send this amp to.
It looks like there is no place working on Plinius amp in Michigan.
Might try Chicago, or send it to Plinius Repairs in CA.

Again, thanks.

I looked at the photos pretty carefully, and the one thing I see that I’m suspicious about involves two of the output transistors in the right channel, the circuitry for which appears in the left half of the second photo.

At the extreme left of the circuit board you’ll see ten power transistors that are attached to a metal sidewall of the chassis, each of which has three leads (connections) to the circuit board. The lowermost of those transistors is near the bottom left of the photo, and the uppermost of those transistors is near the top left of the photo. Counting from the bottom up, the third and the fourth of those transistors appear to have a grayish blob straddling (and perhaps short-circuiting) the two uppermost of their three connections.

Perhaps a close-up photo of those transistors would provide further insight.

BTW, the two glass fuses in each channel (four total), which are not far from the center of the photo, are "DC rail" fuses, which should provide some degree of protection for the output transistors. But without having a schematic or otherwise being familiar with the details of the design it’s hard to say what "some degree" means.

Good luck. Regards,
-- Al

Agree with almarg you need at schematic to simplify repair it can be done without but you may have to through parts at it that look suspect. If you can find an old school tech in your area that has year of experience trouble shooting you may be able to have it fixed for peanuts. If the 2 or 3 graying transistors or resistors are your problem you could be looking at pocket change in parts. You may laugh but the guy that works on my tube and solid state gear on the side works for the school board fixing media equipment and before that had a television repair business. He began his career in the 60's working at a television station. So finding someone local is possible. I don't think running amp without speaker hook up did it, positive and negative must have crossed, good luck you will get it running again.

Not good :-(

When you say "speaker wire detached", do you mean BOTH the wires were uplugged from the right terminals or only one ?  Is it possible you could have shorted the speaker output ?  Typically, the amps should be protected against speaker shorts but nothing is guaranteed.