05-23-2011, 08:32 PM
As Ron sez pay close attention to the HV at the plate and screen grid. If low try a new 84 tube. Also measure the grid bias by connecting the + meter to the cathode and the - to the control grid. Should see around -8v or so. Too low grid bias will cause distortion and cause the 41 to draw excessive plate current. I took a quick look at the schematic and see they added a little negative feedback around the 41. The cathode is tied to the high side of the speaker and receives it's ground though the output transformers secondary. This is done to improve the low frequency response and lower distortion.
Terry
Terry
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 it!
Terry
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