04-18-2013, 08:24 AM
First, let me introduce myself...
My name is Jeff. I run a website called Vintage Volts (http://www.vintagevolts.com) where I report on, reminisce, and generally discuss vintage electronic devices of all types.
While I usually focus on electronic devices which existed during my lifespan, I have found myself intrigued by a much older radio model, a Philco 19.
It was mainly my wife's desire to have an old "cathedral style" radio in the house because our house was built in the early 1930's. She is adding period items to our current decor.
We picked up this Model 19 at a flea market for $45. It looked nearly complete and the body was in very good shape. A small section of laminate is lifted, but can easily be glued back down and looking good as new. We were even able to scrape off some (duct tape?) residue along the back edge of the radio. It looked like someone had taped a cover on the back at one time and used strong tape to do so. The tape residue was very dry and could easily be scraped away using the edge of a credit card.
After a bit of cleaning and wood treatment, the finish is astounding for it's age. A previous owner must have intended to replace the speaker cloth eventually, but opted to cut out a section of cardboard from a restaurant picture menu and fill the cloth space with that instead. We had just replaced that cardboard with replica cloth.
What this leaves us with is getting the radio chassis running. Throwing caution to the wind, I checked to see if everything was where it needed to be (tubes, etc.) and I fired it up. I got lights, I got static from a dirty volume knob, but I got no signal, just a minor hum. Oh... and I saw a 44 tube that wasn't quite glowing as much as the other 44 tube. So, I decided to check the tubes.
The 44 that was glowing good had a broken top connector. It pulled right off, leaving a thin wire coming from the glass tube. Nothing appeared wrong with the other 44 tube. As I pulled each tube out of their sockets to clean/inspect them, I noticed the 75 tube glass was "twisting" slightly in its base. I've worked with tube TVs a LONG time ago and realized that a tube is NOT supposed to do that. The rest of the tubes appeared to be in good condition.
After ordering a used 75 and two NOS 44 tubes. I replaced the bad ones and fired it up again. The "activity" of the radio seemed different. I heard more of a hiss and hum, instead of just a hum as before, but could not receive any stations. Now it was time to break out the multimeter.
Let me point out that I have a trade school degree in electronics, but I don't practice in the field. However, I am more than comfortable, if not experienced, with repairing electronic devices such as these radios.
I first checked the filament voltages. On all tubes but the 80, I got 6.6v. The 80 only had 5.5v. That made no sense until I looked at the schematic and seeing that the 80 gets a different filament feed from the transformer. That makes sense to me as to why the filament voltages are different, but it doesn't make sense to me as to why they designed it that way. Why not feed all filaments from the same source?
Then, using a repair reference I found online, I checked the P-K voltages on the tubes. Most of them should be in the 230-260VDC range, but mine were all over the place, ranging from 160-270VDC. At this moment, I'm typing these results from memory as I'm not at my workbench to double-check the values and to which tubes those values belong. All I know at the moment is that there is something wrong with the radio.
My first assumption is that the transformer is bad. Which will be an issue for me because I'm not finding any good (affordable) resources for authentic replacements. The transformer is not leaking any material, but I believe it's not running to specifications because of what I noticed on the filament voltage for the 80.
BTW, the two electrolytics that would have been mounted between the transformer and tuning dial have been replaced with more modern versions, which are mounted in the rats nest with all of the other under chassis components. When I say "more modern", I mean in the 1970's or something. Those electrolytics just have that kind of appearance and manufacturing finish to them.
Assuming (and hoping) that this radio still has a chance to live again, I'm stuck on what I should do next. Should I trace the problems, fixing them as I go, or should I just consider completely dismantling the chassis and rebuilding it stage by stage, replacing defective parts as needed?
I'm thinking it'll be best (albeit more arduous) to dismantle the chassis. The hardest part will be keeping track of where everything goes, even if I take plenty of pictures beforehand. However, the chassis looks "unclean." Stripping it down would give me the opportunity to clean and polish it to look brand new again. I'll just need to commit to the time that level of restoration will take.
Thanks for reading, and any advice will be appreciated!
Jeff
My name is Jeff. I run a website called Vintage Volts (http://www.vintagevolts.com) where I report on, reminisce, and generally discuss vintage electronic devices of all types.
While I usually focus on electronic devices which existed during my lifespan, I have found myself intrigued by a much older radio model, a Philco 19.
It was mainly my wife's desire to have an old "cathedral style" radio in the house because our house was built in the early 1930's. She is adding period items to our current decor.
We picked up this Model 19 at a flea market for $45. It looked nearly complete and the body was in very good shape. A small section of laminate is lifted, but can easily be glued back down and looking good as new. We were even able to scrape off some (duct tape?) residue along the back edge of the radio. It looked like someone had taped a cover on the back at one time and used strong tape to do so. The tape residue was very dry and could easily be scraped away using the edge of a credit card.
After a bit of cleaning and wood treatment, the finish is astounding for it's age. A previous owner must have intended to replace the speaker cloth eventually, but opted to cut out a section of cardboard from a restaurant picture menu and fill the cloth space with that instead. We had just replaced that cardboard with replica cloth.
What this leaves us with is getting the radio chassis running. Throwing caution to the wind, I checked to see if everything was where it needed to be (tubes, etc.) and I fired it up. I got lights, I got static from a dirty volume knob, but I got no signal, just a minor hum. Oh... and I saw a 44 tube that wasn't quite glowing as much as the other 44 tube. So, I decided to check the tubes.
The 44 that was glowing good had a broken top connector. It pulled right off, leaving a thin wire coming from the glass tube. Nothing appeared wrong with the other 44 tube. As I pulled each tube out of their sockets to clean/inspect them, I noticed the 75 tube glass was "twisting" slightly in its base. I've worked with tube TVs a LONG time ago and realized that a tube is NOT supposed to do that. The rest of the tubes appeared to be in good condition.
After ordering a used 75 and two NOS 44 tubes. I replaced the bad ones and fired it up again. The "activity" of the radio seemed different. I heard more of a hiss and hum, instead of just a hum as before, but could not receive any stations. Now it was time to break out the multimeter.
Let me point out that I have a trade school degree in electronics, but I don't practice in the field. However, I am more than comfortable, if not experienced, with repairing electronic devices such as these radios.
I first checked the filament voltages. On all tubes but the 80, I got 6.6v. The 80 only had 5.5v. That made no sense until I looked at the schematic and seeing that the 80 gets a different filament feed from the transformer. That makes sense to me as to why the filament voltages are different, but it doesn't make sense to me as to why they designed it that way. Why not feed all filaments from the same source?
Then, using a repair reference I found online, I checked the P-K voltages on the tubes. Most of them should be in the 230-260VDC range, but mine were all over the place, ranging from 160-270VDC. At this moment, I'm typing these results from memory as I'm not at my workbench to double-check the values and to which tubes those values belong. All I know at the moment is that there is something wrong with the radio.
My first assumption is that the transformer is bad. Which will be an issue for me because I'm not finding any good (affordable) resources for authentic replacements. The transformer is not leaking any material, but I believe it's not running to specifications because of what I noticed on the filament voltage for the 80.
BTW, the two electrolytics that would have been mounted between the transformer and tuning dial have been replaced with more modern versions, which are mounted in the rats nest with all of the other under chassis components. When I say "more modern", I mean in the 1970's or something. Those electrolytics just have that kind of appearance and manufacturing finish to them.
Assuming (and hoping) that this radio still has a chance to live again, I'm stuck on what I should do next. Should I trace the problems, fixing them as I go, or should I just consider completely dismantling the chassis and rebuilding it stage by stage, replacing defective parts as needed?
I'm thinking it'll be best (albeit more arduous) to dismantle the chassis. The hardest part will be keeping track of where everything goes, even if I take plenty of pictures beforehand. However, the chassis looks "unclean." Stripping it down would give me the opportunity to clean and polish it to look brand new again. I'll just need to commit to the time that level of restoration will take.
Thanks for reading, and any advice will be appreciated!
Jeff
