The PHILCO Phorum
40-120 full restoration - Printable Version

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40-120 full restoration - Cody Winters - 08-29-2026

Hello Y'all got a good one for you. I recently picked up a 40-120 off of Ebay for 35$
since i was looking for a small prewar radio i could buy on the cheap and restore.
since i'm also a ham i've built a tube transceiver from scratch but this is my first original
radio restoration. after getting it in the mail i took the chassis out of the cabinet and did a full inspection.
as expected some of the wires have crumbling insulation and the capacitors are in sad shape. the previous owner broke
the cardinal rule by plugging it in and stated that " it buzzes when powered on" so hopefully nothing was damaged. 
i'm planning on fully restoring the radio inside and out, but first things first i'm going to correct the obvious problems with the electronics. 
looking inside i can see ten capacitors and i got the part numbers off of all but one. 
I want Y'all to check behind me and make sure i got all the capacitor part numbers correct for this model of radio. the x2 refers to quantity 
the numbers i got are: 30-2403A, 30-4119 S x2, 30-4572 S, 30-4479 S, 30-4604 D, 30-4519 S x2, 30-4519 D, and lastly a mystery cap that 
states "type 584" and ".05" which i assume is .05 MFD but i want to make sure of that.

RE: 40-120 full restoration - klondike98 - 08-29-2026

Welcome to the Phourm!
Icon_wave

Here's a link to the schematic for your set in our digital library: https://philcoradio.com/library/download/service%20info/yearbooks/1940/split/Part45-Philco%201940%20RMS%20Year%20Book.pdf

The cap part numbers aren't particulary important any more but the cap values are listed in the parts list in the above referenced schematic.

Should be fun.

(I deleted your first two posts as they were duplicates. Your first two actual posts are delayed for moderation and then after that they will appear imediately. Welcome!)

RE: 40-120 full restoration - glyphmon - 08-29-2026

Cody,

Welcome from another relative newbie.

Bob beat me to sharing the schematic.

As I have learned, it is helpful to refer to the schematic part number in discussion on the forum.  I think you have identified most of the parts, but I think you will find it helpful to ask by schematic part number (e.g., Capacitor 29, a 0.04mfd with Philco part number 30-4119), especially for your mystery parts.  The schematic and chassis diagram is also very useful for identification.  Not sure about the "S" or "D" on some of your parts, as Philco doesn't list those as part of their part numbers in the part list so I would imagine they may be interchangeable.

Best wishes,
Roy

RE: 40-120 full restoration - klondike98 - 08-29-2026

I should have also noted that the cap in the actual radio are not always the same part numbers as listed in the schematic parts list. The capacitance and working voltages are usually the same but the part numbers sometimes differ...why, you ask...as our founder Ron liked to say...."only the folks at Philco know the answer to that and they are no longer around to be asked."

RE: 40-120 full restoration - Cody Winters - 08-29-2026

FIrst off, thanks to Klondike98 for dealing with the duplicate posts, i was assuming that something was wrong on my end since my internet is dodgey at times and i'm a hopeless dimwit when it comes to computers. and secondly thanks for the tip on the schematic, i've been studying it at length to make sure everything matches. so far so good. tomorrow i'll take some photographs to show the caps inside the chassis.

RE: 40-120 full restoration - Cody Winters - 08-30-2026

here are the photos i got of a few of the capacitors. 
based on what i'm seeing it looks like it was untouched since new.
but being over 80 years old who knows.

RE: 40-120 full restoration - radiorich - 08-30-2026

Hello Cody,
I really enjoy working on sets that are completely new or perfectly done! I’ve had to repair way too many jerry-rigged radios, TVs, and cars in my life. For example, I have a beautiful GE from the 50s with a bakelite case, but the chassis was a real mess from smoke and rust damage, so I found another radio with a bad cabinet.

I take lots of notes and photos, and even mark wires before replacing parts so I can go back and review them. Over the summer at my folks’ place, I decided to start restoring a TV, and the next time I’ll work on it is in December, so I’m keeping plenty of notes, videos, and photos.

Sincerely Richard

RE: 40-120 full restoration - MrFixr55 - 08-30-2026

Hi Cody,

From the State with Wall Street to the State with "Y'All Street, Welcome to the Phorum!!! We are glad that you are here.

I echo what others have recommended but want to add 3 caveats:

With this type of set, the most damage from powering up without recapping could be blowing out the rectifier. Since the set has no power transformer, there is no power transformer to fry due to shorted filter caps.

The bigger issue is that this is either a "Hot Chassis" set or a "Warm Chassis set, meaning that the "low end" of the heater string and B- are connected to the chassis, either directly or through a cap or cap and resistor. If the set is plugged in in such a manner that this point is at "hot" potential, the chassis becomes dangerous to touch. If this point is connected to the neutral leg of the source of power, it becomes safer WHILE THE POWER SWITCH IS ON. You see, what makes this even more of an issue is that from the dawn of these AC-DC transformer-less sets to the end of the vacuum tube era (and even some transistor sets) is that the manufacturers had the habit of placing the power switch between the AC Line and this Low end og the heater string and B- connection point. This means that one way or another, the chassis can be warm or hot. For example, the plug is inserted with the B- / Low end of the string connecting through the power switch to the "neutral" leg of the power outlet (Neutral is at ground potential). With the switch on, the chassis is at "ground" potential and the danger of shock when touching the chassis is nil. Now, turn the power switch (in the neutral leg) OFF. Even at operating temperatures, the heater string resistance is rather low, say 800 ohms baser on 0.15A heater string and 120V supply). So now, through the heater string, the chassis is hot. This is still enough to wreck the hearts of us old guys in quite a few cases. However, when tubes are cold, their resistance is much less than 800 Ohms, therefore much more current is available, wrecking more hearts. This is usually bad for the person getting shocked. Therefore I always rewire my transformerless sets so that the low end / B- connects directly to the neutral conductor of a polarized power cord and I move the power switch to the hot end of the power line and to the high end of the heater string and to the input of the rectifier. This may cause a slightly higher amount of hum but makes for a safer set.

Finally, having a "peri-WWII set means that you have rubber wire. There are 2 ways of dealing with this. One way is to cut one end of the cable, clean off the rubber and reinsulate either with "spaghetti" (varnished cloth straw-like insulating tubing) or heat shrink tubing. The alternative is to replace the failing wiring with type AWM 22 gauge solid or stranded wire with a minimal rating of 300V.

It's a little cramped in there but these are rather simple sets.

Hope this helps. Good luck. Keep posting! Glyphmon says that he is new, but I think he is on his 4th radio already. I have almost 100 radios, TVs, HiFi sets, etc. but I'm a little sick and, being 71 years old, I have had time to collect this much.