I figured since the last half dozen or so radios I've purchased have been Philcos, I should sign up here! I just picked up this Philco 39-40 from an estate sale. Was the end of the sale, and everything was half price- it was marked $50, and I got it for $25. Didn't have the space for it, but I fell in the love with the design- really nice veneer on this radio, and there was the fact that if I didn't pick it up, it would probably end up going to the dump. Figuring since it's a late 30's model, and looked relatively complete, I thought it would be easy to get going even for someone with limited skills/knowledge like me!
Couple things I noticed: I assumed the volume control would have a power switch built in, but found that there's a hole under the overhang above the speaker with a toggle switch in it. I thought someone added it, but the hole is very clean and the wiring doesn't look hacked. Is that likely to be original? Kind of a clever way to hide a switch.
I also noticed nothing's been touched under the chassis, but... lots of rubber wires everywhere, in varying condition. Most of them seem ok (it was stored inside), but what worries me are the ones from the power transformer which are cracking. I've never dealt with power transformers before, and it's a bit intimidating... so many wires. So, am not really sure how to tackle that. I figure if I leave it the way it is, my house is likely to burn down...
One of the 42's has a rattle when you move it... replace it? Also the rectifier tube has a dark/burnt looking spot in the glass near the base, didn't look quite right to me- replace that too?
I've already ordered reproduction pushbuttons for it. The photos were before I cleaned the cabinet- it really is in nice shape, and the grille cloth looks almost new.
I believe toggle switch is original on that model. For rubber coated wire it is best to replace all of it, changing one wire at a time so you won't get confused.
as far as the transformer leads I have put shrink tube as sleeves on the wire and just carefully shoved it into the bell housing to fix crumbly wire. rattle tube i would look for replacement, dark burn't spot on rectifier is "getter flash" Where they burned off any excess oxygen in the tube during manufacturing process, don't worry about that.
(This post was last modified: 04-09-2017, 10:19 AM by simplex1040.)
I had a 39-25 power transformer with bad wires. Took it out of the chassis, took off the clam shells, stripped the rubber wire insulation and cover it with heat shrink tubing of the correct colors. Often just squeezing the wire with pliers will crumble the bad rubber. After reassembly check continuity and for shorts.
Charles (simplex1040) is right, the toggle on-off switch is original to this set.
Heed the warnings from simplex1040 and Bob (klondike98). Replace the insulation on all of the wires coming out of the power transformer. The best way to do this is to unsolder each lead from where it connects inside the radio, taking careful notes as you go. Once you have the transformer removed, remove the bells (covers or "clam shells") as Bob said. Then after you have the bells off, use a pair of needle nose pliers to remove the old insulation from one wire and one wire only. Now slide some heat shrink tubing over that wire, pushing it as far into the paper insulation of the transformer as you can. This is the safest way to handle replacing transformer wiring insulation. Anything less runs a serious risk of shorting out the transformer. There is still a risk if you do this work, but it is much safer than just leaving it alone. Use a lighter or heat gun to shrink the tubing.
Now repeat this process for each of the remaining transformer leads (wires).
You really should use color coded heat shrink tubing, available from Mouser Electronics among others, so you will know which wire is which. You can use the same colors as the originals (as closely as possible), or do as I do and use the standard RMA/EIA color codes instead (green for filament leads, red for high voltage secondary (rectifier plates), orange or other contrasting color (a compromise for red with yellow tracer) for high voltage center tap, yellow for rectifier filament leads, black for 115 volt AC primary).
If you do not do this - and, yes, it is a fair amount of work - you run the risk of your transformer shorting out.
Don't condemn that rattling 42 tube quite yet. Check if you can see what is rattling and if it is visible inside the glass envelope.
If you don't actually see a piece of metal or glass inside, its probably a loose piece of cement inside the bakelite base. Sometimes a lump of the cement that fastens the base to the glass envelope breaks loose and rattles around when you shake the tube, in which case it is harmless and nothing to worry about.
As Simplex mentioned, a dark spot inside the glass just above the base is normal on later production replacement tubes. The original tubes had the silvery mirror getter flash, while later tubes have the dark deposit. If the dark spot turns milky white, then you have something to worry about, as air has entered the tube and there is no more vacuum.
Thanks for all the responses! I guess what I thought would be a simple 'few new capacitors and hope it works' is really going to be a bit more... involved.
Ron, you mention that there is still a risk even if I disassemble the transformer covers and replace the rubber coating... would that be if the wiring underneath the paper has already shorted? And amateur question; to check for shorts, am I basically just checking to make sure there is no continuity between windings, and checking the ohms for each winding to make sure they're close to the schematic?
I guess regardless, I should probably check each winding first to make sure I'm not dealing with a bad transformer before I do all this work.
David, thanks for the link to the schematic. It seems very well labeled, and I notice the transformer colors are labeled as well- that will make it easier. Perhaps an uninformed question: each winding has two wires, one for each end, eg. 2 whites for the primary... is there a difference between either of them? Hypothetically, if I connected the one which is on the other side of the power switch, and switched it with the one connected to the other side of the line... would that matter?
I could not see anything moving around inside that 42 tube, so it might be ok. I did manage to break off one of the tube caps while cleaning the others... oops. I think I can re-solder that, maybe.
In the meantime I've been trying to polish the metal dial surround- it's better, not perfect. Just been using metal polish. What I find very cool is that the presets have stickers on them for local stations, eg. WICC, WOR, etc, many of which are still around.
For the primary wires, it does not matter which side is connected to the switch.
Not too far under the paper the wires connect to the small magnet wire of the transformer.
the only real issue I have had is with the insulation Before under the paper as they are kind of "free" under the bells.
Ron is just making you wary that with any old electronic there is always the risk that something is shorted or could be.
I would not let that worry you. If the transformer does not look burned or melty, it is prob ok. I would not worry about testing it for shorts. I never do unless it looks burnt or melted.
Figured I'd update this... yes, everything in the radio looks great other than the wiring. I noticed the dial string slipped off, so, this may be why it stopped getting use.
But... now that it's spring, I've found an excuse to put off the many hours of re-wiring ahead of me and instead focus on 2 cabinet projects. Already posted about the 38-8 I'm refinishing (I need to stop getting consoles...) in the cabinet section. So I'll revisit this when bad weather hits.
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