Ron Rich wrote:As MatTech stated--it's most likely NOT a tube ! What he did not state is: running it in "that condition" can lead to very serious problems. Leave it un-plugged till someone with knowledge of that unit can look at it-- Ron Rich
Exactly Ron.
As an experienced bench technician, I can count on one hand how many times a "failed tube" has come across my service bench.
Rarely...
And that's going by literally hundreds of vintage radios, phonos, etc. that have come into the shop for "repairs".
From a 1929 Mifflinburg 5-tube breadboard-style radio, to a 1964 Rca Victor console stereo, tubes in these units have held up well over the decades.
The main causes of failure to vintage products are those pesky old wax-filled capacitors, and to a lesser extent old carbon resistors.
Half the time the resistors have opened up because of the bad capacitors, because the stress (improper voltages changes) on the circuitry from bad caps causes them to carry too much current, and eventually open up.
Even transformers become useless after they've dealt with overloaded current, and short out, drip tar, etc.
While do-it-yourselfers will always exist, there's nothing to match having an experienced tech go over the unit.