02-21-2017, 11:03 AM
I am relatively new to the electronic restoration and understanding of these old sets, so bear with me here. I can solder, replace parts, caps, controls, use a multimeter, but as far as understanding, processing, and diagnosing electronic issues, I am a novice. I have been reading up on things to check and do when it comes to the electronic restoration of these sets and understand most of it except that I have not found a good description of how to actually check B+ voltage or what this even tells us. I have a vague idea, but no hypothetical light bulb has gone on for me with this. I have 2 very similar sets doing different things and I was going to try and attach these sets as real world applications involving the testing of B+ voltage and what this can tell me in these 2 cases, if anyone has the time to explain.
Case#1. Philco 37-610 - recently cleaned, replaced bad volume pot and all caps including electrolytic, filter bakelite, and paper with correct values, above recommended voltage ratings, and good clean solder connections. The electrolytics used were older unused multisection can types that tested good before installation. After all this and checking tubes as well, the set played with no hum or distortion, however volume level was not as high as it should be, not many stations picked up on the am band (more came in with the short wave band), and after 1/2 hour of playing the volume dropped dramatically, a burning smell started, and after shutting off I noticed that one of my multisection electrolytic caps was physically leaking out the bottom of the chassis.
Case#2. Philco 37-630 with shadow meter - recently acquired from someone who just replaced all the electrolytic, filter, and paper caps, and power cord. Tubes were supposedly checked and tested good. Previous owner said that the set still slightly hums, no stations come in and no static or volume at all, just silence, and that the (metal) 6f6 power tube "overheats". He had mentioned that this made him concerned about the power transformer. Can someone help me to understand how he came to this diagnosis and how an overheating power tube can point to the transformer, or if this guy really has no idea what he is talking about. . .
I want to learn to be exact and knowledgeable about this, not just throw parts at it until it works.
Thanks in advance
Case#1. Philco 37-610 - recently cleaned, replaced bad volume pot and all caps including electrolytic, filter bakelite, and paper with correct values, above recommended voltage ratings, and good clean solder connections. The electrolytics used were older unused multisection can types that tested good before installation. After all this and checking tubes as well, the set played with no hum or distortion, however volume level was not as high as it should be, not many stations picked up on the am band (more came in with the short wave band), and after 1/2 hour of playing the volume dropped dramatically, a burning smell started, and after shutting off I noticed that one of my multisection electrolytic caps was physically leaking out the bottom of the chassis.
Case#2. Philco 37-630 with shadow meter - recently acquired from someone who just replaced all the electrolytic, filter, and paper caps, and power cord. Tubes were supposedly checked and tested good. Previous owner said that the set still slightly hums, no stations come in and no static or volume at all, just silence, and that the (metal) 6f6 power tube "overheats". He had mentioned that this made him concerned about the power transformer. Can someone help me to understand how he came to this diagnosis and how an overheating power tube can point to the transformer, or if this guy really has no idea what he is talking about. . .
I want to learn to be exact and knowledgeable about this, not just throw parts at it until it works.
Thanks in advance
