11-10-2013, 03:17 PM
This is my first tube radio restore and I've been reading a lot and think I am coming to some sort of vague understanding of what I need to do but I have a few questions.....as well I've attached the two different versions of the schematics for the 48-472 in case it helps someone else out in the future...
1st question:
For starters here's what I know about the condition of the radio....
When turned on the AM comes in ok, a bit of hum, but ok(super loud when the volume is turned up all the way), the FM on the other hand is distorted at a much lower volume and nothing comes in clear. I had another radio so took a 12AU6 out of that one and replaced the 12AW6 in the philco and voila the FM now works, although it's still a much lower volume, a lot of stations now come in cleaner...so of course I'm now thinking about replacing all the tubes becaue I have no way to test them....anyone have any thoughts on that? Anyone have tube tester in Seattle and want to help me out?
2nd question:
In the Photo below, I understand that the obviously large paper looking capacitors are in fact paper capacitors and need replacing. I can add up about 23 of those from the parts list and visually. As well on the parts list they are listed as .01uf, .02uf, .006uf, etc. so my assumption is this type I can readily purchase and the voltage/capacites are identically listed today on a website like "antique electronic supply"? Second part of this question is are the other capacitors in the photo, the ones circled, mica and ceramic? I think obviously the traffic light looking one is a mica one, but the others, like the small brown ones almost look like mini paper capacitors, what about the bulbous brown ones and the strange plasticy tan one on the far right? And based off what I've read I shouldn't try to replace any of those first off? If I attempt to crossreference with the schematic this seems correct but hard to see exactly.
[Image: http://www.johngrace.com/files/external/capacitors.jpg]
3rd question:
So im confused about reading the parts list for ordering capacitors. Some of the Identification codes list "cer." after them so I assume these are ceramic capacitors identified as such. Then the ones listed as .01...type values I'm assuming are paper and I can order those, but what about the ones below...for example the "cathode bypass" a giant silver tube in the underside of the chasis. Other forums list this as electrolytic, should I just replace it? As well the "stabilizing cap" large black tube? And the "filter," large black cardboard tube on top of chassis, does than need replacing and what type of capacitor is that, is it just three stuffed into the tube?
[Image: http://www.johngrace.com/files/external/parts1.jpg]
4th question:
This is where the AM antenna is connected, does any of this have to do with FM or is that just the long white cord on the far right? Also the thing circled is broken. Doesn't seem like it needs to be fixed but there was a piece of black wire which came with the radio should that black wire go from the black wire on the broken piece to one of the antenna type terminals?
[Image: http://www.johngrace.com/files/external/back.jpg]
5th question:
How do I make the radio safer at this point? Some online advice is to add a fuse into the power cord. It's easy to trace where the power cord goes into the radio so I can easily replace it so what kind and how do I add the fuse? As well I've read about isolation transformers. Do you guys build them inside your radio to make it safer?
I guess that's it for now. My main concern is making it safe so I don't electrocute myself or a cat, although at this point I don't think I will be plugging it in anymore until the repairs are made, and also putting an order in for capacitors/tubes so I can get started. One last question anyone have a url for wire I can order in case I need some?
1st question:
For starters here's what I know about the condition of the radio....
When turned on the AM comes in ok, a bit of hum, but ok(super loud when the volume is turned up all the way), the FM on the other hand is distorted at a much lower volume and nothing comes in clear. I had another radio so took a 12AU6 out of that one and replaced the 12AW6 in the philco and voila the FM now works, although it's still a much lower volume, a lot of stations now come in cleaner...so of course I'm now thinking about replacing all the tubes becaue I have no way to test them....anyone have any thoughts on that? Anyone have tube tester in Seattle and want to help me out?
2nd question:
In the Photo below, I understand that the obviously large paper looking capacitors are in fact paper capacitors and need replacing. I can add up about 23 of those from the parts list and visually. As well on the parts list they are listed as .01uf, .02uf, .006uf, etc. so my assumption is this type I can readily purchase and the voltage/capacites are identically listed today on a website like "antique electronic supply"? Second part of this question is are the other capacitors in the photo, the ones circled, mica and ceramic? I think obviously the traffic light looking one is a mica one, but the others, like the small brown ones almost look like mini paper capacitors, what about the bulbous brown ones and the strange plasticy tan one on the far right? And based off what I've read I shouldn't try to replace any of those first off? If I attempt to crossreference with the schematic this seems correct but hard to see exactly.
[Image: http://www.johngrace.com/files/external/capacitors.jpg]
3rd question:
So im confused about reading the parts list for ordering capacitors. Some of the Identification codes list "cer." after them so I assume these are ceramic capacitors identified as such. Then the ones listed as .01...type values I'm assuming are paper and I can order those, but what about the ones below...for example the "cathode bypass" a giant silver tube in the underside of the chasis. Other forums list this as electrolytic, should I just replace it? As well the "stabilizing cap" large black tube? And the "filter," large black cardboard tube on top of chassis, does than need replacing and what type of capacitor is that, is it just three stuffed into the tube?
[Image: http://www.johngrace.com/files/external/parts1.jpg]
4th question:
This is where the AM antenna is connected, does any of this have to do with FM or is that just the long white cord on the far right? Also the thing circled is broken. Doesn't seem like it needs to be fixed but there was a piece of black wire which came with the radio should that black wire go from the black wire on the broken piece to one of the antenna type terminals?
[Image: http://www.johngrace.com/files/external/back.jpg]
5th question:
How do I make the radio safer at this point? Some online advice is to add a fuse into the power cord. It's easy to trace where the power cord goes into the radio so I can easily replace it so what kind and how do I add the fuse? As well I've read about isolation transformers. Do you guys build them inside your radio to make it safer?
I guess that's it for now. My main concern is making it safe so I don't electrocute myself or a cat, although at this point I don't think I will be plugging it in anymore until the repairs are made, and also putting an order in for capacitors/tubes so I can get started. One last question anyone have a url for wire I can order in case I need some?
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