Odd transformer with 6X4 tube mounted on top.. smoking more than my uncle Frank

[freqazoidiac]

howdee doodee folkies.. this is my first post here..great resource herea t DIY!

I bought a Bell and howell reel to reel a while back for $5.00 at a thrift shop as I noticed it had tubes and Input, Output and contained speakers .
I thought immediately that it would be a nice sound for running one of my
guitars or keys through.

The first thing i did was check the quality of the audio when recording to tape in case I wanted to use this for tape effects. Nothing special or unique, and rather muddy.
Running my guitar through it, and using the 1/4" output to hook up
to my 15" keyboard amp..that's a different story. HUGE sound, a little noisy
and TONS of grit..well that's if I turn the main volume up to saturate..degenerates the tone very nicely for a distressor effect and psychedelic fuzz tones.
When it's toned down, it's just very smooth and nice, kind of a jazz tone.
It has two little lights on the front that light up when maxed..kind of like
one of those Tube Magic eyes (but not as cool)

so onto ripping this apart to lighten the chassis up.
Reaching into it and the main weight was from the HUGE transformer like motor that drove the tape mechanism. Lot's came out of this beast, 75% for tape drive.

There are 2 awesome 12ax7 Telefunkens (one wrapped in metal), 2 bell and howells and a 6X4.

This 6X4 is perched on top of a heavy but small transformer that is at the start of the Power supply chain followed by an old switch type fuse.
This Tube/transfomer integration is one i am very curious about..I have never seen
this..what exactly does this do? Does the tube act as a voltage regulator?
and.. it has begun smoking, alot.. burning inside. I have read that a bad cap on the board will cause this..what do you all think? This problem has rendered my audio fun null at the moment!

SO that's my problem and if someone can help me , that would be fab

[SY]

The tube is being used as a rectifier. This looks like an early attempt at a wall-wart!

Indeed, if the supply feeds filter caps and one or more of them have gone to Paradise, it could cause smoking. It's likely that the transformer's insulation has also started to fail; a lot of these veterans were insulated with fancy wax paper, and if that's started to burn, you've got a time bomb even if you fix the rest. If the internal winding wire insulation is starting to char, then double that warning.

If it were me, I'd just build a supply with new components (that's probably a $50 deal), and put the old one on display. Otherwise, you're facing a potentially serious safety issue.