[dobulee]

Hi John -- I was asking about using a jumper when checking things on the bench without the yoke connected. You're right, w/ the yoke connected there is no need.

Bill was right on the money with this one.

The 4k Resistor between 375 and 220V is bad - it reads okay at room temp, but reads close to open if you measure soon after power down. How's that for a positive temperature coeffecient. Fun.

The filament went on the original 5U4 -- but I've double checked isolation between the filament windings and all the other taps -- no problems. The open circuit AC voltage across the 5U4 filament is 5.1. Not sure why things went wrong.

Incidentally, I decided to go for the diode route instead of another 5u4 for now. Since the 5u4 drops somewhere around 40Vpeak at full load, I ball-parked some series resistance (220 Ohm 5 W) for each diode in the full wave rectifier. This turned out to be pretty dang close.

With a bunch of parallel 50k 1W resistors bodged in for now where the 4k Power resistor should be, I finally pulled the variac out of storage, and brought the set up slowly. The 370V BUS leveled out at 381, the 200V BUS at 195, and the 125V Bus at 81V. Can't win 'em all. One of the series resistors is high -- I'll get to it later.

At this point, I could hear the vertical output transformer rev-up!

I put the chassis back into the cabinet, and hooked up an aux audio input, -- sound! Not bad for how far off the biasing is due to the 125V BUS. The 6k6 audio output tube has an interesting blue glow....
At this point, there was still no sign of any HV -- I suspect the horizonal output tube, who's getter flash now looks suspiciously oxidized. I'm not having the greatest of luck with ebay'ed tubes!

Back to the bench, and an oscilloscope.

1st capture is 370V Bus Ripple voltage AC coupled at 10V/division. Ripple is about 4Vpp -- I'll take that!

2nd capture is the vertical drive at the grid of vertical sweep output tube. Looks reasonable, stable, and linear!

3rd capture is Tap C of the horizontal oscillator transformer. Gotta admit, i'm not exactly sure what waveshape I should capture here, but the general frequency is about right - about the 15kHz ballpark, although it's not particularly stable.

That's it for now -- all of the about captures are free running oscillators with no video or RF applied.

Is there anything specific I should check out before some new 6BG6 horizonal output tubes arrive?

Any tips, thoughts or comments appreciated

Alex