[Frank]

My 37-690 is making the same kind of noise as described in the first post. There must be a common problem with these sets. My set already had the Philco modification done to it. They also replaced the candohm with a new Philco unit that contains only two sections. I went ahead and re-replaced the 300 and 75 ohm resistors that were Micamold resistors with new 5 watt resistors. Still makes that cracking sound.

There is a voltage fluctuation that occurs when this noise happens. I put a lug from my meter on to one of the primary leads of the driver transformer and saw this happen. More tracing needed, I guess....