01-25-2009, 11:40 AM
Last time I changed out a selenium I did just what you did but I used 100 ohm 5 watt instead of 50 ohms. If the capacitance of the filter cap replacements you used were larger than the originals, you might have to go higher on the resistance value to keep the B+ under control. I personally wouldn't want to see anything above 130 volts plate voltage on the 35C5, or whatever you have in your set. I'd also replace that 22 ohm "fuse" with a new one. They tend to become unreliable because of decades of heat.
Bring the set up slowly with the variac and monitorthe B+. If it is too high, add more resistance, and of course vise versa.
As an aside, I have a Philco 50-620 on the bench now with the same problem. The B+ also feeds the filament string I'm going to be a lot more careful since this design feeds the delicate 1.4 volt filaments. With new filter caps, and the higher mains voltage we commonly now see, these sets need to be tamed down. Even with the tube rectifier versions of portables, the filaments are usually way over stressed.
Bring the set up slowly with the variac and monitorthe B+. If it is too high, add more resistance, and of course vise versa.
As an aside, I have a Philco 50-620 on the bench now with the same problem. The B+ also feeds the filament string I'm going to be a lot more careful since this design feeds the delicate 1.4 volt filaments. With new filter caps, and the higher mains voltage we commonly now see, these sets need to be tamed down. Even with the tube rectifier versions of portables, the filaments are usually way over stressed.
