The power supply caps are BAD.
New ones, and replacing the bridge rectifier, along with some coupling caps ISN'T EXPENSIVE.
That's the MINIMAL you can do for the old lady.
As I stated before, I've DONE MANY of those radios, but you can do whatever you want.
New ones, and replacing the bridge rectifier, along with some coupling caps ISN'T EXPENSIVE.
That's the MINIMAL you can do for the old lady.
As I stated before, I've DONE MANY of those radios, but you can do whatever you want.
Small update:
Replaced the selenium rectifier with a silicon bridge and a series resistor. Hum is not gone.
Furthermore, voltage still drops too much. (B+ only 250V now).
Tried with a known good EL84. Hum is not gone either.
Tomorrow I'll try to replace the supply caps and see if that helps.
Replaced the selenium rectifier with a silicon bridge and a series resistor. Hum is not gone.
Furthermore, voltage still drops too much. (B+ only 250V now).
Tried with a known good EL84. Hum is not gone either.
Tomorrow I'll try to replace the supply caps and see if that helps.
Guess what, it's the supply caps.
Piggybacked two caps I had laying around, the hum is now down to tolerable levels. Should've listened to you guys.
Guess what, it's the supply caps.
Piggybacked two caps I had laying around, the hum is now down to tolerable levels. Should've listened to you guys.
Unlike many on the internet, I don't mince words when I know about something.
And I always provide truthful information.
Being in the "service business" for 40+ years, I had many customers to please, and keep my reputation from sinking.
Glad you finally listened.
By the way, there's probably also another smaller capacitor that needs replacing farther up in the set.
Look for it, it may be something around the 4uF value.
Change it.
A last update:
I ended up replacing both supply caps, the rectifier, the last coupling cap, the fuse and power cable.
I also cleaned and lubed the scale and cleaned some pots and contacts.
It now plays very nicely on the strong stations. There is quite a bit of reflection pickup in between the strong stations, so an alignment could help - but I don't have the gear for that, unfortunately.
I ended up replacing both supply caps, the rectifier, the last coupling cap, the fuse and power cable.
I also cleaned and lubed the scale and cleaned some pots and contacts.
It now plays very nicely on the strong stations. There is quite a bit of reflection pickup in between the strong stations, so an alignment could help - but I don't have the gear for that, unfortunately.
Congrats that you worked it out so far 
!
It's always difficult for us (well, at least for me
) to exactly nail down an issue without having the patient before me.
Best regards!
!It's always difficult for us (well, at least for me
) to exactly nail down an issue without having the patient before me.Best regards!