I am trying to understand the failure mode of one of these in a 3A6.
Both cathode tabs are melted and the 47^ screen resistor is smoked.
With great trepidation, I replaced the defective tube after checking
the asssociated 6DJ8s, xistors, and diodes. The replacement held and
the screen resistor stayed cool. However, there is a DC imbalance on
both traces that the controls won't comp. I suspected possible
filament-cathode leakage in the otherwise fresh looking dead tube. No
way to check for that now. I definitely don't want to risk a
presently good 8233/E55L. Any ideas on the probable failure mode?
Thanx in advance; Steve
P.S., Hi Stan, nice to find you again. Great Resource!