09-11-2014, 06:41 PM
well the radio is finished!
thanks for all the help and suggestions, and for bearing with my questions.
i believe that the suggestion about checking rivets and bolts attached to the chassis was the key to eliminating the hum issue.
the reason i say " i believe" is because i basically tore the whole thing down again and built it up better than i had previously.
in the first incarnation, i had left some of the original wiring, figuring that it was fine.
and i still believe it was, however i can be a bit of a perfectionist and just decided to do it right.
all the parts and wiring came out, all the chassis rivets and bolts were tightened if possible (bolts) and given the pro gold treatment.
i think this really helped all the old oxidized metal.
everything looks so much better than the way i had it before, and the hum is all but non existent.
i did make one pretty big boo boo though.
its kind of embarrassing to admit, but when i put the parts back in, i somehow put the 10uF cap in backwards!
i had the chassis on its side, with the speaker hooked up, and was doing the "turn it on and listen to the beautiful music" test. no noise at all from the speaker, but turning the sensitivity trimmer cap produced a few clicks from it.
in an unbelievably lucky twist, my wife came in to the radio room to tell me i'd been in there too long, so i stood up and turned my back on the still "on" radio to tell her that i was almost done.
then...
BOOOOM!!!
big plume of smoke and a shriek from my wife. i turned back around to find capacitor remnants everywhere.
just moments before the cap blew, i had my face pretty close to that chassis.
thank goodness for her checking up on me.
after turning the radio off and unplugging it faster than the flash himself, i peered in to ponder my predicament.
and there was my mistake staring me right in the face.
the arrows on the side of the cap pointing right to the pin on the rectifier tube.
DOH!
again luckily, i had the forethought to order two of them when i made my parts order for this radio.
one new cap soldered in, cardboard fluff blown out, a THOROUGH check for any other mistakes, and the radio came to life like it hadnt in 50+ years.
no hum, and after a few tweaks to the trimmer caps, she was picking up nearly every AM station in town with a 6 foot piece of wire.
i gotta tell ya, the sound had a timbre to it that id not heard before. it was really addictive and made me want to sit and listen to sports radio and pretend it was 1944.
(whatever that was like LOL)
i delivered it to the person who had me restore it, and it worked just as well at his house. thank goodness again.
im really proud of this one, and if i ever come across one again, i will surely grab it up to do one for myself.
i sure learned a lot doing this project, and it was nice to not worry about burning up sensitive PC board traces for once!
i do have some before and after pics on my phone, including the blown cap.
so after i figure out how to get them from my phone in to my email, i will post them here for posterity.
thanks again to a wonderful group of very helpful and knowledgeable people.
you guys rock.
LC
thanks for all the help and suggestions, and for bearing with my questions.
i believe that the suggestion about checking rivets and bolts attached to the chassis was the key to eliminating the hum issue.
the reason i say " i believe" is because i basically tore the whole thing down again and built it up better than i had previously.
in the first incarnation, i had left some of the original wiring, figuring that it was fine.
and i still believe it was, however i can be a bit of a perfectionist and just decided to do it right.
all the parts and wiring came out, all the chassis rivets and bolts were tightened if possible (bolts) and given the pro gold treatment.
i think this really helped all the old oxidized metal.
everything looks so much better than the way i had it before, and the hum is all but non existent.
i did make one pretty big boo boo though.
its kind of embarrassing to admit, but when i put the parts back in, i somehow put the 10uF cap in backwards!
i had the chassis on its side, with the speaker hooked up, and was doing the "turn it on and listen to the beautiful music" test. no noise at all from the speaker, but turning the sensitivity trimmer cap produced a few clicks from it.
in an unbelievably lucky twist, my wife came in to the radio room to tell me i'd been in there too long, so i stood up and turned my back on the still "on" radio to tell her that i was almost done.
then...
BOOOOM!!!
big plume of smoke and a shriek from my wife. i turned back around to find capacitor remnants everywhere.
just moments before the cap blew, i had my face pretty close to that chassis.
thank goodness for her checking up on me.
after turning the radio off and unplugging it faster than the flash himself, i peered in to ponder my predicament.
and there was my mistake staring me right in the face.
the arrows on the side of the cap pointing right to the pin on the rectifier tube.
DOH!
again luckily, i had the forethought to order two of them when i made my parts order for this radio.
one new cap soldered in, cardboard fluff blown out, a THOROUGH check for any other mistakes, and the radio came to life like it hadnt in 50+ years.
no hum, and after a few tweaks to the trimmer caps, she was picking up nearly every AM station in town with a 6 foot piece of wire.
i gotta tell ya, the sound had a timbre to it that id not heard before. it was really addictive and made me want to sit and listen to sports radio and pretend it was 1944.
(whatever that was like LOL)
i delivered it to the person who had me restore it, and it worked just as well at his house. thank goodness again.
im really proud of this one, and if i ever come across one again, i will surely grab it up to do one for myself.
i sure learned a lot doing this project, and it was nice to not worry about burning up sensitive PC board traces for once!
i do have some before and after pics on my phone, including the blown cap.
so after i figure out how to get them from my phone in to my email, i will post them here for posterity.
thanks again to a wonderful group of very helpful and knowledgeable people.
you guys rock.
LC
