Hi everyone. I think this may or may not be my first post here. All the guys at ARF say you guys are great. I'm a bit of a radio novice but I've done about 20 including one model 89 so not a complete idiot, I'm an incomplete one (-:
So far on this one I have found an open speaker transformer and that sort of brought my usual "starting from audio and working my way back method to a halt. If anyone know if I could get away with a temporary sub from another radio please let me know. What I planned if I cant do that is pulling the pair of 42 tubes out and working from there.
Please give me any tips or gotchas I should know about. I'm sure there are gonna be a lot more stuff. This old radio seems incredibly made. Practically have a guitar level power amp. (-: I'll post pics soon. Thanks yall.
Hello Pete, welcome to the Phorum. We're all a little incomplete here but in most cases we seem to put together enough information to have progress. An ARF referral, I didn't think we had that kind of reputation.
So, it looks like you're on the right track with that output transformer (opt). I usually test all the coils and transformers at the start of a restoration in case there's a need to fix ot replace one. You'll want to find a transformer primary with around 10k ohms impedance. If you have one at 7k then it will do in a pinch. All you're looking for at this point is some noise. Keep the volume to a minimum. Any p/p transformer from a chassis with 6F6s will work perfectly. If you check the 42 tube characteristics it says the plate impedance is 7k - 10k. The 6F6 is 10k.
People with 16X experience will chime in shortly with all kinds of stuff to do. Show us some pics and good luck with your restoration.
Thank you RodB
Could someone point me in the direction of a good schematic, layout and parts list? The ones I have found are pretty low resolution.
Thanks.
Hello peteleoni. In the Philco Radio Library you will find schematics for the model 16. You will have to determine which run you have in front of you. It will be listed on the model label affixed inside the cabinet. Hope they are of better quality. Take care, - Gary https://philcoradio.com/library/index.ph...ams-vol-1/
"Don't pity the dead, pity the living, above all, those living without love."
Professor Albus Dumbledore
Gary - Westland Michigan
While that schematic is somewhat better than the one I had Its still not where I can see it well. Chalk it up to me being somewhat of a novice. I would love to buy a clear one if thats available.
Wow! The 8uf filter caps had a "pressure fit" neg connector with the insulator pressing the lug to its case. It looked like stock. I guess 1933 was a terrible year and they were doing with what they had? But this model 16 was a rich man's radio. Anyone know the story here?
Could someone explain to me how the output transformer is wired? I have an open primary and I have aquired a possible replacement which has a 3 wire center tapped primary. Oddy I see only a 2 wire primary on the original and only a 4 wire cable from radio to field coil / output transformer-speaker.
The two end leads of the primary winding goes to the pin 2 of the two 42 tubes (plate pin). The common color code for these wires are brown and blue, red is the center tap which is connected the field coil. Philco has their code for wiring. The secondary are two stiff wires protruding from the lower side of the opt as I remember it. Here's something you'll probably need: https://philcoradio.com/library/index.ph...34-44-144/ As for a better diagram I don't know what you've seen but this one is pretty good: https://philcoradio.com/library/download...%20165.pdf There's not a lot of choices as they all come from the same source.
When my pals were reading comic books
I was down in the basement in my dad's
workshop. Perusing his Sam's Photofoacts
Vol 1-50 admiring the old set and trying to
figure out what all those squiggly meant.
Circa 1966
Now I think I've got it!
Per the Philco service documents, the green and white wires are the 2 legs of the transformer primary. These go to the plates of the 42s. The green/white wire is common to the output transformer center tap and the field coil. This wire connects to the junction of filter choke #85 and 8.0uF cap #88, the output of the rectifier and filter. The final wire, blue, is the output of the field coil and connects to the junction of 2.0uF cap #62B and 7.750 Ohm resistor #77. This is the B+ supply to the rest of the radio.
Ignore the color dots for now; they were not placed there by Philco, and may not accurately represent the modern color coding that Rod describes. Since the colors of the wiring are quite faded, you can do the following:
Ohm between the 2 wires on the right side of your speaker. The reading should be about 1400 Ohm. If so, this is the field coil and the darker wire is the "Blue - White" wire described in the schematic. The other lighter color wire is common to the center tap of the transformer and the field coil.
Ohm between that "common" wire and each of the other 2 wires. You should get readings that are approximately equal (there can be a 50 - 100 ohm difference. These are the "legs" of the output transformer that connect to the plates of the 42s. BTW, I don't think that the resistance value for the output transformer primary stated in the schematic (5300 Ohms) is accurate. That may be the impedance but it is not the resistance.
Hope this helps.
"Do Justly, love Mercy and walk humbly with your God"- Micah 6:8
"Let us begin to do good"- St. Francis
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