DuMont RA-102 vertical transformer bad?

[Phil Nelson]

Thanks. I did replace the micas under the power chassis, along with resistors in that area.

On this set, the previous owner eliminated the doorknob HV filter cap, possibly because he was using a substitute CRT that had an aquadag coating (the 12JP4 that I'm using has no aquadag). I got a new doorknob from Surplus Sales of Nebraska and installed it as shown in the schematic. I suppose it's possible that the new doorknob is bad; I can pull one from another restored TV and try substituting that, to rule it out.

Meanwhile, I removed the HV transformer and coated the whole thing with thin corona dope, along with the likely connections on the HV line and 1B3GT HV rectifier socket. This seems to have quieted any corona noise.

If subbing the doorknob has no effect, I'll look into the horizontal circuits as suggested by username1.

Regards,

Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html