Hi BG Piano Man,
That is a nice looking cabinet.
Welcome to the Philco Phorum. Lots of phine phriendly pholks phull of knowledge on all things Philco and other phine antique electronics. (See a pattern here?)
The schematic diagram in the below link is on our website in the "Philco Library" section.
https://philcoradio.com/library/download...8-1949.pdf
The instructions for the record changer, from this website are located here:
https://philcoradio.com/library/download...8-1949.pdf
How you go about this depends on your electronic skills or desire to learn and your desired outcome. Remember as a piano tuner, you are already a skilled craftsman, so don't let the unknown here scare you.
Now what you have here is a monaural radio-phono set that receives the modern AM and FM bands. The amplifier puts out 7 Watts of power to a 10" or more likely 12" "electrodynamic" speaker" (a speaker with an electromagnet instead of a permanent magnet). The amplifier employs "2 6K6 (or possibly 6V6, there is a discrepancy in the schematic) pentodes in "Push-Pull" with negative feedback.
The record changer has 2 tone arms, one for playing 78 RPM records (the standard from the invention of the Victor phonograph till about 1950) and "LP" (33 1/3 RPM) introduced by Columbia (not RCA Victor) early post WWII. This is not as high end as a Fisher or Scott of the era but represents some of the better work of Philco and stands up to anything offered by any manufacturer at the time other than the most expensive top of the line equipment.
In terms of gutting the unit and replacing the original electronics with modern units, this will prove rather controversial. I have seen many table radios that were prized for their styling hollowed out and a Bluetooth speaker substituted for the original electronics, and the original electronics scrapped. I cringe at that. The speaker in this set cannot be connected to just any amplifier, as the "field coil" must be powered by approximately 70 Volts.
I think that you can get the best of both worlds here by mounting a pair of stereo speakers in the cabinet while leaving the originals in place. This can be done several ways, the easiest by having them face the rear at angles to bounce the sound off the wall. One can also modify the 2 cloth covered panels to accept the original speaker (right side) and additional speakers (both sides.) There are many compact amplifiers on the market that can be discretely hidden in the record storage well of the cabinet and be fed by Bluetooth or direct wiring to an MP3 Player, computer, etc.
If you repair the radio, the phono connection can be unplugged, and an MP3 player or Bluetooth signal can be substituted. You would be surprised at how well this piece of 1940's technology can sound with an external input!
In any case I recommend that at the very least, you preserve the entire right side of the unit, including the radio chassis, escutcheon, glass dial and wood face panel.
The act of actually repairing the radio is done in several steps. The first is to inspect the radio for burned components and wiring with deteriorated insulation. Philco and several manufacturers used rubber wiring in the mid to late 1930s to early 1940s. this rubber insulation was known to deteriorate. I believe that the only rubber on this unit may be the power cord, but I may be incorrect. If the wiring is good and there is no evidence of burned components, replace the electrolytic filter "caps" (capacitors, sometimes also referred to as condensers) C102, C103A and B any other electrolytic capacitors. You can tell the electrolytics as they usually have values in excess of 1.0 uF (mfd or "microfarad"), and to replace the 2 caps on the power inlet, C100 and C101, with 0.01 uF "Class Y" safety capacitors. These steps MUST be done before considering powering up the radio. However, it is strongly urged that you replace the above capacitors and all "paper foil" capacitors in the set. These are those "waxy things" with values usually between 0.001 and 0.5uF. Usually, ceramic disc caps and mica caps can, and should be, left undisturbed.
How to replace caps and solder can be learned by the many You tube videos on the subject. The easiest technique is to cut the wires to the cap as close to the cap as possible, clean the ends of the wires that led into these caps and bend them to a tight hook. Thread the leads to the new cap through the hooks just formed, trim off excess lead from the new cap, crimp with pliers and solder. This negates the complex act of having to disturb solder connections at the sockets and switches. It is important to not change the location of wiring and components, especially near the FM tuned circuits.
Next, check all transformers using an ohmmeter or DVM, for opens. Check all resistors. All resistance readings should be within 20% of the values stated on the schematic.
Next, test tubes if a tester is available. At the very least, inspect the tubes for breakage or a milky white "getter" coating in the tube.
Next, carefully power up the set. It is recommended to use a "Variac" or other variable out AC transformer capable of handling at least a 200 watt load. If this is not available, look up "Dim Bulb" tester on the internet. This is merely a series of lamp sockets in parallel with each other, hooked up in series with the radio. Load these sockets with several high wattage incandescent bulbs and tighten them one at a time. If the bulb glows brightly, there is an issue with the work. Increase the voltage to the radio by tightening more bulbs until the radio plays. The voltage to the radio will still be low, the radio may not play. If this test passes (no smoke) then the radio can be plugged in directly. Do monitor the power transformer for excessive heating. The transformer should never get too hot to touch.
Hope this all helps!! take it one step at a time, keep us posted on your progress, and please ask for help when needed. There are no dumb questions and we here atht e Phorum are always happy to help!
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