10-11-2017, 08:56 AM
Frank,
I don't think I'd recommend that you take everything apart, unless you just want to for fun. There's too many opportunities to mess up. Of course, it seems like whoever was in there before you did mess up, so you have to find all his mistakes.
I'd recommend a focused troubleshooting approach. The Philco service document and troubleshooting guide is one way to start. It should guide you through some basic procedures. Or, my favorite reference is Marcus and Levy, Elements of Radio Servicing. You can download it in 6 pdf files from here: http://www.antiqueradios.com/archive.shtml Sometimes you can find it on eBay or a used book store.
Probably the first thing to do is to track down the tube pin voltage problems, since you know you have to solve those anyway. Anything that is off by, say, 10% or more, track down the wiring to that pin and make sure it's picking up voltage from the right place and that the components in the path are in spec.
If you have a way to test the tubes, that could possibly save you some steps. Sometimes a bad tube will throw voltages off. I had a Brand Z portable not too different from your 46-350 that worked but sounded bad. Some of the voltages were way off, and I wasted a lot of time trying to track down why. On a whim I replaced the 3Q5 and bingo, it sounded good and the bad voltages were, if not right on, a lot closer.
If you don't get function back after fixing the voltage problems, there are relatively simple tests to go stage-by-stage to isolate the problem area, then you can focus on exactly what is wrong with the problem stage. Start with the output stage, and work backward, using the tests you get from Philco, Marcus and Levy, or you can ask here.
If you have the Philco troubleshooting guide, it divides the schematic into quadrants and includes a simplified component placement and connection diagram for each quadrant. You could use that to make sure Mr. "X" made the right connections with the right value components. This is in the package I got from Chuck Schwark. Be sure to check with the list of production changes, so you can see the changes between the Code 121 that is represented in the diagrams and the Code 125 that you have.
One other thing, you could free up some space and make things more visible in there by restuffing the 4 section electrolytic can and getting those replacement electroytics out of the chassis. Some guys like doing this, some hate it. If it's not your thing, no problem. I like to do it if I can.
And finally, I don't know anything about your frequency generator app, but if you connect anything in the radio to your phone, be sure to isolate it with a .01 uf cap so you don't put any DC high voltage on your smart phone. You might want look into a stand-alone signal generator. There are lots on eBay, some modern, some vintage, for lots different of price points. Some of the recommended stage tests do require that you put an audio frequency or modulated radio frequency onto specific tube pins.
I don't think I'd recommend that you take everything apart, unless you just want to for fun. There's too many opportunities to mess up. Of course, it seems like whoever was in there before you did mess up, so you have to find all his mistakes.
I'd recommend a focused troubleshooting approach. The Philco service document and troubleshooting guide is one way to start. It should guide you through some basic procedures. Or, my favorite reference is Marcus and Levy, Elements of Radio Servicing. You can download it in 6 pdf files from here: http://www.antiqueradios.com/archive.shtml Sometimes you can find it on eBay or a used book store.
Probably the first thing to do is to track down the tube pin voltage problems, since you know you have to solve those anyway. Anything that is off by, say, 10% or more, track down the wiring to that pin and make sure it's picking up voltage from the right place and that the components in the path are in spec.
If you have a way to test the tubes, that could possibly save you some steps. Sometimes a bad tube will throw voltages off. I had a Brand Z portable not too different from your 46-350 that worked but sounded bad. Some of the voltages were way off, and I wasted a lot of time trying to track down why. On a whim I replaced the 3Q5 and bingo, it sounded good and the bad voltages were, if not right on, a lot closer.
If you don't get function back after fixing the voltage problems, there are relatively simple tests to go stage-by-stage to isolate the problem area, then you can focus on exactly what is wrong with the problem stage. Start with the output stage, and work backward, using the tests you get from Philco, Marcus and Levy, or you can ask here.
If you have the Philco troubleshooting guide, it divides the schematic into quadrants and includes a simplified component placement and connection diagram for each quadrant. You could use that to make sure Mr. "X" made the right connections with the right value components. This is in the package I got from Chuck Schwark. Be sure to check with the list of production changes, so you can see the changes between the Code 121 that is represented in the diagrams and the Code 125 that you have.
One other thing, you could free up some space and make things more visible in there by restuffing the 4 section electrolytic can and getting those replacement electroytics out of the chassis. Some guys like doing this, some hate it. If it's not your thing, no problem. I like to do it if I can.
And finally, I don't know anything about your frequency generator app, but if you connect anything in the radio to your phone, be sure to isolate it with a .01 uf cap so you don't put any DC high voltage on your smart phone. You might want look into a stand-alone signal generator. There are lots on eBay, some modern, some vintage, for lots different of price points. Some of the recommended stage tests do require that you put an audio frequency or modulated radio frequency onto specific tube pins.
John Honeycutt
