Help! Afterglow blew up

[Bluenote]

I have a pair of Afterglow 2A3 power amps I built way back in 2000. Hadn't listened to them for a month or so. Fired them up and noticed a transient his from one side, dropped the needle on an LP and nothing was coming out of the right channel. Looked down to inspect the amps, make sure they had power etc and noticed a strange purplish glow all through the 2A3 tube on the right. Then all of a sudden heard a pop and then smoke started coming out from under the base. Got the power shut off and unplugged. When I turned it over I could not tell what had burned. Any ideas? Do tubes have catastrophic failures and take other stuff out with them??

Thanks for any help.

 

[Paul Birkeland]

Purple glow inside the tube is almost always gas inside the tube that should be there.

Take the tubes from the working amp and try them in the other amp, but by "try" I mean to measure voltages.  The ones that are most important are the A1, A2, A3, and A4 DC voltages.

-PB

 

[Bluenote]

Thanks! The rate limiting step here may be finding the old manual from 15 1/2 years ago, so I know what to check and what the target voltages would be etc. If I can't locate it anywhere is there any chance that a PDF exists?
The glow I had mentioned was very different from anything I had seen before--very intense and bright.

Kyle

 

[Paul Birkeland]

You can just post each voltage on the 4 pin socket.  Even without having the manual, a rough estimate of these values is not too hard to come by.