Dave, you mentioned the 240RB4 datasheet. Could you please point me to a PDF copy of it?I agree, something doesn't look right. I'll have a think about that one later...
However, datasheets for the 240RB4 CRT indicates that the filament supply (on pins 3 and 4) should read 12V a.c.
However, there could be a problem in reading this supply with a conventional multimeter because the a.c. supply is derived from the EHT supply at a high frequency.
Dave
I have seen that before. It seems strange that Google finds no actual datasheet.Well, not the true datasheet for the 240RB4 - but the manual for rejuvenating the CRT. It identifies the heater voltage and the type of adapter to use.
A 240RB4 CRT specifies a heater voltage of 12.0V and a test base of CR/CA 7.
Looking at the end of the document identifies the CR/CA 7 and what leads/pins corresponds to which electrodes.
I haven't (yet) identified the actual full datasheet.
Dave