07-22-2021, 12:46 PM
Now that it is daytime and I’m more coherent here are some more things that might be useful:
This was my first Philco experience so the first thing that I dealt with was the Bakelite terminal block. I cleaned out the insides and put two new .01 mf Y2 safety caps from each line to ground. I also connected a new 8’ polarized line cord and fuse inline on the “hot” side (also the on/off switch side). The Philco repair bench has a good article on Bakelite blocks: https://www.philcorepairbench.com/how-to...te-blocks/
For capacitors and resistors I sourced from JustRadios.com. I replaced paper capacitors with a mix of polypropylene and polyester film tubular axial capacitors. I used .5 watt carbon comp resistors except for a few cases where 1 watt were spec’d in the service manual. They can be identified by looking at part number ending in “4340.” There are a couple in the power supply section for voltage dropping and a couple of voltage dividers in the scratch eliminator circuit plus maybe a couple more here and there. I did not replace any mica caps.
When evaluating output transformer replacement I found this article helpful: http://www.radioremembered.org/outimp.htm
I measured the dc resistance of the voice coil at 3.0 ohms. I used the rule of thumb to arrive at impedance of 3.75. I used the Hammond table for their 125D transformer: https://www.hammfg.com/electronics/trans...a-125e.pdf
I settled on lugs 3 and 5 for primary impedance between 7000 and 8800. Lugs 2 and 4 would yield 9000 to 11200. The 6V6 push-pull setup is good for maybe 10000 ohms. I also tried lugs 2 and 4 but really couldn’t tell any audible difference. Would be interested in comments on which way is better.
The power transformer performed per spec once I slowly powered up with variac. It fooled me for a while because the primary wising measured 2.8 to 3 ohms. The schematic indicated primary should be 28 ohms. I guess this is an eeeor on schematic but I have seen this same indication
for other radios incorporating this transformer so it concerned me for a while. Here is an article on power transformers I found useful: https://www.radioremembered.org/xfmr.htm
Other than the 5U4 rectifier the only questionable tube I had was the FM1000. It has a small crack in it but still works. It is not really easy to find but I spotted one on eBay recently and snagged it. Better be nice to your FM1000s.
The M-4 record changer is in good shape. I cleaned, lubed, and adjusted according to service manual. I had to get a needle for the magnetic cartridge. I found an Astatic N501-3s on eBay. It works fine. You might also find a viable replacement at thevoiceofmusic.com. They also will service idler wheels. I’ll probably have mine serviced before too long but it works pretty good even though the rubber looks a little dry.
The Philco service manual has really good alignment instructions and is available in the Philcoradio.com library.
I’ve got some video of this thing operating and will try to post soon.
This was my first Philco experience so the first thing that I dealt with was the Bakelite terminal block. I cleaned out the insides and put two new .01 mf Y2 safety caps from each line to ground. I also connected a new 8’ polarized line cord and fuse inline on the “hot” side (also the on/off switch side). The Philco repair bench has a good article on Bakelite blocks: https://www.philcorepairbench.com/how-to...te-blocks/
For capacitors and resistors I sourced from JustRadios.com. I replaced paper capacitors with a mix of polypropylene and polyester film tubular axial capacitors. I used .5 watt carbon comp resistors except for a few cases where 1 watt were spec’d in the service manual. They can be identified by looking at part number ending in “4340.” There are a couple in the power supply section for voltage dropping and a couple of voltage dividers in the scratch eliminator circuit plus maybe a couple more here and there. I did not replace any mica caps.
When evaluating output transformer replacement I found this article helpful: http://www.radioremembered.org/outimp.htm
I measured the dc resistance of the voice coil at 3.0 ohms. I used the rule of thumb to arrive at impedance of 3.75. I used the Hammond table for their 125D transformer: https://www.hammfg.com/electronics/trans...a-125e.pdf
I settled on lugs 3 and 5 for primary impedance between 7000 and 8800. Lugs 2 and 4 would yield 9000 to 11200. The 6V6 push-pull setup is good for maybe 10000 ohms. I also tried lugs 2 and 4 but really couldn’t tell any audible difference. Would be interested in comments on which way is better.
The power transformer performed per spec once I slowly powered up with variac. It fooled me for a while because the primary wising measured 2.8 to 3 ohms. The schematic indicated primary should be 28 ohms. I guess this is an eeeor on schematic but I have seen this same indication
for other radios incorporating this transformer so it concerned me for a while. Here is an article on power transformers I found useful: https://www.radioremembered.org/xfmr.htm
Other than the 5U4 rectifier the only questionable tube I had was the FM1000. It has a small crack in it but still works. It is not really easy to find but I spotted one on eBay recently and snagged it. Better be nice to your FM1000s.
The M-4 record changer is in good shape. I cleaned, lubed, and adjusted according to service manual. I had to get a needle for the magnetic cartridge. I found an Astatic N501-3s on eBay. It works fine. You might also find a viable replacement at thevoiceofmusic.com. They also will service idler wheels. I’ll probably have mine serviced before too long but it works pretty good even though the rubber looks a little dry.
The Philco service manual has really good alignment instructions and is available in the Philcoradio.com library.
I’ve got some video of this thing operating and will try to post soon.
