Electrolytic capacitors dry out over time and cause hum. There are a series of radios called "Little Nipper". You should also have a model number which may start with 9XS or 9TX. Schematics are available here on nostalgiaair.
Norm
: We recently found a Little Nipper Radio that was purchased in 1940. I'm trying to get it to work, but it just hums. When we tune near a station, you can hear a distorted signal coming through at a low level. I have been unable to find a similar model to this one on the net. Perhaps someone here can help. It has a brown plastic cabinet and ivory knobs. The glass on the tuner is lit from behind. It has 5 tubes. Any info would be appreciated.
Ed.
: Ed.
I think that must be the one. The label inside says it was built by RCA Canada. It was purchased in Toronto in 1940 as a present to my mother-in-law on her 16th birthday. Thank you for your reply and for the schematic. Tom.
Ed.