12UP4 condition

[cluelessgame]

Originally Posted by EdKozk2

I was able to get the brightness control to vary the crt's brightness. I disconnected the existing crt filament leads from pins 1 and 12. I then taped them off. Then connected a 6.3 volt ac @ 600ma transformer to the filament pins. The existing brightness wire on crt pin 11 is unsoldered, then connected to pin 1 or 12. This was an easy to be able to vary the brightness on a most likely broken internal cathode connection. Thanks again jr_tech. The filament transformer output leads can not be grounded, it should float. I tried this with a 6 volt battery, a 6 volt dc wall wart and even a 7.2 volt dc wall wart. All of the filament sources worked. The higher voltage produced a brighter picture of course.
Ed

does this mean you're turning the filament into the cathode itself?
I may have to try this with the 21ZP4 in my Admiral. I think it has the same issue