Yesterday, 06:55 PM
Sorry I haven't been responding but my neighbor that I was caring for ended up in the hospital with complications from COVID and metastatic cancer that rapidly spread to her liver. She passed last week at home under hospice care very peacefully with friends, including me, at her side, 2 hours after the priest gave her last rights. God's work must truly be our own.
The 14BT2 couldn't be from 1936, as the tubes for the set were not released until 1938. These tubes were developed by Sylvania and these should be the longer skinnier version. BTW, looks like an adaptor in the 1A7 socket, I guess for a 1R5. Does the grid cap go to the side of the adaptor? 1A7s should be found easily on ePay. I believe that the 14BT2 was vintage 1940. Had an "RCA" Jack for a phono input. Bottom Line is if you fixed a 14BT2, you can fix the Philco, because other than the pushbuttons and the weaker 1A5 as opposed to the stronger 1Q5 output tube used by the RCA, the circuits are rather similar. If you paid $30 for yours way back when, they haven't increased in value. I bought mine for $35 on ePay back in 2013.
Re the Philco, it is rare to see resistors burned unless something shorts. In this case, looking at the pic, one end goes to chassis. If the other end goes to a junction with the grid resistor for the output and a wire that should be B-, then this is definitely the "bias" resistor and all B Current goes through it. If the wire is not at that junction, just add it. that is 1 less wire that you need to figure out. A- is chassis ground. Those 2 red wires going to the switch are A+ and B+. Your mission, figure out which is which. Trace the wires to the switch and see where the wire "on the other side" of the DPST switch goes. B+ goes to a junction between the output transformer B+ Lead, Pin 4 of the 1A5 and one of the leads of C16. A+ goes to Pin 2 of all the tubes. I may be repeating from my previous post, sorry. (Look up in redundant in the dictionary, it says see "redundant")
Don't worry that the wires to the push buttons are cut, the rotary switch selects manual tuning broadcast, pushbutton broadcast or police / shortwave.
Pull the tubes and ohm each between Pins 2 and 7. these are the filament pins and there should be a rather low resistance.
Check part # 16, a 2 section electrolytic. better yet, just cut it out and replace it. It is likely shorted. This can be common for 'lytics. While rare for paper tubular condensers to short in battery sets as opposed to the House current sets where these get hot, it is not impossible. The culprit here would be C32, a 0.0005 uF Cap. However, this is from the 1A5 Output tube plate to ground, and the transformer primary impedance is 25K Ohm for that tube (I believe). DC resistance could be lower. Best to just clip out and replace the caps. Ohm the Output xformer to make sure it is not toast.
The 14BT2 couldn't be from 1936, as the tubes for the set were not released until 1938. These tubes were developed by Sylvania and these should be the longer skinnier version. BTW, looks like an adaptor in the 1A7 socket, I guess for a 1R5. Does the grid cap go to the side of the adaptor? 1A7s should be found easily on ePay. I believe that the 14BT2 was vintage 1940. Had an "RCA" Jack for a phono input. Bottom Line is if you fixed a 14BT2, you can fix the Philco, because other than the pushbuttons and the weaker 1A5 as opposed to the stronger 1Q5 output tube used by the RCA, the circuits are rather similar. If you paid $30 for yours way back when, they haven't increased in value. I bought mine for $35 on ePay back in 2013.
Re the Philco, it is rare to see resistors burned unless something shorts. In this case, looking at the pic, one end goes to chassis. If the other end goes to a junction with the grid resistor for the output and a wire that should be B-, then this is definitely the "bias" resistor and all B Current goes through it. If the wire is not at that junction, just add it. that is 1 less wire that you need to figure out. A- is chassis ground. Those 2 red wires going to the switch are A+ and B+. Your mission, figure out which is which. Trace the wires to the switch and see where the wire "on the other side" of the DPST switch goes. B+ goes to a junction between the output transformer B+ Lead, Pin 4 of the 1A5 and one of the leads of C16. A+ goes to Pin 2 of all the tubes. I may be repeating from my previous post, sorry. (Look up in redundant in the dictionary, it says see "redundant")
Don't worry that the wires to the push buttons are cut, the rotary switch selects manual tuning broadcast, pushbutton broadcast or police / shortwave.
Pull the tubes and ohm each between Pins 2 and 7. these are the filament pins and there should be a rather low resistance.
Check part # 16, a 2 section electrolytic. better yet, just cut it out and replace it. It is likely shorted. This can be common for 'lytics. While rare for paper tubular condensers to short in battery sets as opposed to the House current sets where these get hot, it is not impossible. The culprit here would be C32, a 0.0005 uF Cap. However, this is from the 1A5 Output tube plate to ground, and the transformer primary impedance is 25K Ohm for that tube (I believe). DC resistance could be lower. Best to just clip out and replace the caps. Ohm the Output xformer to make sure it is not toast.
"Do Justly, love Mercy and walk humbly with your God"- Micah 6:8
Best Regards,
MrFixr55
