11-24-2018, 10:56 AM
Hello Pat,
I am currently restoring a 40-200 and performed everything you did, caps, resistors... Worked well for a day or two and started getting a hum. Caps are all good. It ended up being the phase inverter tube socket. I cleaned the socket using 90% alcohol and welder's tip cleaning brush. Plugged in the tube and bingo, no more hum.
On another radio I restored the problem was a solder joint on a tube pin. I re-soldered it by placing the tube upright, heating the pin and letting the solder get sucked up into the pin.
You may also want to check all of your solder joints. I use a chopstick to poke around under the chassis.
I am currently restoring a 40-200 and performed everything you did, caps, resistors... Worked well for a day or two and started getting a hum. Caps are all good. It ended up being the phase inverter tube socket. I cleaned the socket using 90% alcohol and welder's tip cleaning brush. Plugged in the tube and bingo, no more hum.
On another radio I restored the problem was a solder joint on a tube pin. I re-soldered it by placing the tube upright, heating the pin and letting the solder get sucked up into the pin.
You may also want to check all of your solder joints. I use a chopstick to poke around under the chassis.
Denis R.
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