01-06-2022, 08:36 PM
So F should be up to about 150v so overall there's about 35v missing. Would check the AC voltage at pins 1&4 of the 80 tube. Should see 5Vac. Be careful as there's almost a couple of hundred volts DC there too between either pin and the chassis. If you have 5V you may have a weak 80 tube that can't deliver the current needed for the HV in the set.
If you have hi/low sw in hi put it in low if your 5V is below 5V to see if that helps.
If the cap between pins 1&6 is smaller than 2mf that will cause the HV to be low. As a last resort you could add another 2mf in parallel to in = 4mf. That's about as high as you would want to go.
Check resistors in #35, 157 ohm 1545 and 2240. Originally I was thinking the 1000 ohm resistor as it is the filament bias for the 71A. The 157 ohm the filament bias for the 26's. The others are a voltage divider for the hv. With either of these bias resistors off it can cause the tube to draw excessive current and lower the hv line.
As for your choke it's 12.5 Henries @ 80ma 400 ohm pn 3269. The power transformer has a hv winding that is 575vac end to end pn 3271.
GL
If you have hi/low sw in hi put it in low if your 5V is below 5V to see if that helps.
If the cap between pins 1&6 is smaller than 2mf that will cause the HV to be low. As a last resort you could add another 2mf in parallel to in = 4mf. That's about as high as you would want to go.
Check resistors in #35, 157 ohm 1545 and 2240. Originally I was thinking the 1000 ohm resistor as it is the filament bias for the 71A. The 157 ohm the filament bias for the 26's. The others are a voltage divider for the hv. With either of these bias resistors off it can cause the tube to draw excessive current and lower the hv line.
As for your choke it's 12.5 Henries @ 80ma 400 ohm pn 3269. The power transformer has a hv winding that is 575vac end to end pn 3271.
GL
When my pals were reading comic books
I was down in the basement in my dad's
workshop. Perusing his Sam's Photofoacts
Vol 1-50 admiring the old set and trying to
figure out what all those squiggly meant.
Circa 1966
Now I think I've got!
Terry
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