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Hi, Would anyone have a schematic for an RCA Victor model 3-X-521? It's a small table radio supposedly from 1951. Serial no. is U 124327. It works, but hums fairly loudly. I see one burned resistor but I cannot make out the color code. When I know the value, I'll replace this bad resitor and hope the hum stops. Is it likely to be the fix? Would appreciate any & all help. Mark
You probably need power supply capacitors. Look for capacitors inside the radio with values around 8uF to 20uF. You'll probably find two or three; Replace them with polypropylene 250v caps and the hum will probably go away. I found a schematic that may be for your radio on Rider volume 14. It has 35Z5, 50L6, 12SA7, 12SK7 and 12SQ7 tubes. That was a very common tube set for RCA radios. I have a couple of chassis like those myself. One of mine was just like yours when I got it - Working but with a lot of hum. I replaced the power supply caps and it was much quieter.