Rivera Era Concert Amp Question

[bluedogmike]

Greetings All,

First post...
Well I acquired a 80's Concert amp and it was working ok. When I was checking it out. I noticed that the 6L6 tubes were somewhat loose in their sockets, so I pulled them, and like a hurried fool, put one back in the wrong orientation. Well, I have never done this before, and thought it was basically impossible being a keyed socket, but it happened. So when I turned on the amp, and turned off the standby, it smoked. Oops.

So, I saw that I had fried one of the 470 ohm screen resistors. I replaced it as well as the other screen resistor on the 2nd 6l6 tube socket.

Well, now the amp immediately blows fuses when turning off the standby.

My best guess is that the output transformer is damaged, but that's a highly uneducated guess...

Any help would be great, and thanks for allowing me to join the forum.

Mike D

[Don]

Hi Mike. Welcome to the forum. Did the amp still blow the fuse if you turned it on without any tubes in it? If you haven't done that already, I wouldn't do it now. The amp should be properly diagnosed before it's powered up again to prevent further damage.

[phantomman]

My best guess is that the output transformer is damaged, but that's a highly uneducated guess...

Another possibility is that one or both of the power tubes are toast.

[bluedogmike]

Thanks for the suggestions. I did pull all the tubes and it still was blowing the fuse when I switched it off standby.

After I removed the lead to the OT connected to the standby switch it still blew a fuse. So I removed the second wire on the switch which feeds the power supply filter choke and it stopped blowing the fuse.

I pulled the choke and it is shorted from the leads to the case, so looks like I MAY have found the culprit... As it feeds the screen resistors which is what burnt out initially.

Sound reasonable?

Thanks,
Mike D