10-01-2023, 04:31 PM
I would think that you would want to connected pin 1 to B- and not chassis ground.
In this configuration B- is 150,000 ohms above chassis ground to lessen the shock
hazard. This could allow some small amount of ac to be present on the tube's
shield. It's such a small amount that when you touch it bleeds off. That ac voltage
could be the cause of your issue. Oh, B- is easily found at the - side of the filter caps.
Or try adding a .2mf at 630v across the 150,000 ohm resistor.
Or just disconnect the connection from pin 1.
Or replace the faulty 12SQ7 maybe.
In this configuration B- is 150,000 ohms above chassis ground to lessen the shock
hazard. This could allow some small amount of ac to be present on the tube's
shield. It's such a small amount that when you touch it bleeds off. That ac voltage
could be the cause of your issue. Oh, B- is easily found at the - side of the filter caps.
Or try adding a .2mf at 630v across the 150,000 ohm resistor.
Or just disconnect the connection from pin 1.
Or replace the faulty 12SQ7 maybe.
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
![[-]](https://philcoradio.com/phorum/images/bootbb/collapse.png "[-]")
