problems in mystery amp....

[stompjunkie]

Ive got an old mystery amp. No labeling, no identifing marks...looks like someone made the cab in woodshop....

anyway, it's running three 12ax7's into a pair of 6973 power tubes with a 5y3 rectifier. It did run and sounded fine, but now it just hums really really loudly. The rectifier starts red plating after about 20-30 seconds. I replaced the filter caps with no relief. Any ideas?

Thanks for the help.

[Structo]

Have you tried a different recto tube?

Sounds like it is shorted.

[CaseyJones]

Your fuse should blow if the recto is redplating.

You need to test your 6973s. If one iosn't shorted we'll discuss this further...