National SW-54 Thoughts

[Dubis7]

What's the purpose of the filament shunt resistor?

Mine keeps blowing. It was blown when I first got it. I swapped it originally, had no issues, had no issues still when I finished replacing a whole batch of components today, and then I swapped in a bunch of tubes from a non working parts set I picked up and suddenly my R15, which is listed as the "filament shunt" started blowing. It's also blowing out my dial light. Thankfully I have quite a few spares for both.

I'm taking a break before swapping it back again. My desoldering station needs a part and I had to order it, but my next test is going to be swapping those tubes back and replacing the resistor again. Could a dead tube cause that resistor and the dial light to blow on power up? I could very well have an open filament on one of the tubes.