1948 Oldsmobile Radio testing/restoration

Hi again folks,

Pulled my radio out of the pickup over the long weekend and am deciding what to do with it. I’m in a small apartment in Chicago (not much space for storing things like full size auto batteries) and want to start testing it.

Photos here: https://photos.app.goo.gl/6RA1WHk3Mzeaybrj7
Schematics here: https://www.radiomuseum.org/r/united_1_ ... ile_1.html

It looks like it’s in pretty good shape, though I haven’t powered it up. Insides are dusty, but everything is connected, and the speaker look like it’s in good shape. I’m not sure at this point whether I want to just put a modern radio inside the shell, pay hundreds to refurbish/upgrade mine/or just stick with the current radio. I think it’ll depend on whether or not it works as-is. I don’t plan to use it as a daily driver, so I’m not too concerned about limited channels or the chance that AM radio is no long supported. I’m not opposed to just putting a Bluetooth speaker under my seat.

My pickup is converted to a 12v system, but I figure for simplicity, I’ll test the radio and speaker on 6v and then use a reducer when I install it.

——— QUESTION 1 ———
Does anyone have any suggestions for what to use for power while I test it in my apartment? Do I need to buy a 6v auto battery? I was looking at these ... wondering if something like this might work:
- Wildgame Innovations 6-Volt eDRENALINE Tab Style Rechargeable Battery https://www.amazon.com/dp/B004ZWRO30/re ... ZEbC1P4738
- Belker 36W Universal 3V 4.5V 5V 6V 7.5V 9V 12V AC DC Power Adapter Supply for Household Electronics Routers TV Boxes LCD CCTV Cameras - 0.5A 1A 1.5A 2A 2.5A 3A 2500mA Max. https://www.amazon.com/dp/B078LSVVTB/re ... ZEb75J6NK1

——— QUESTION 2 ———
Any tips on cleaning components? Assuming it turns on and can get some audio, I’d love to just
- Clean things up
- Replace things if they really need to be replaced
- Replace the speaker (it’s ~$80)
- Sandblast and paint the shell

A few links I’ve already found in the forums:
- Radio museum link for my radio: https://www.radiomuseum.org/r/united_1_ ... obile.html
- New speaker: https://www.retromanufacturing.com/
- Restoration service: http://www.turnswitch.com/radio1.htm
- New vintage radios: https://customautosoundmfg.com/
- Radio parts: http://www.justradios.com

Old radios are neat, I vote for a restoration if not too much. I wouldn't put new gut in an old radio, I'd rather it go to someone who wants to restore it, and just buy a modern radio if tunes are what you want. It will be cheaper anyway.
I'd look for a solid state voltage converter with an output in the 7.2 - 7.6 volt range and a current capacity of at least a few amps. Tube filaments and inverter buzz coil (if used) will draw more than a modern radio.
Even find a replacement tube would be hard today, but by no means impossible. I'd get on the .net and see if you can find some "radio heads" (radio enthusiast) in Chicago, there have to be some. They could help and would know of sources for needed part if required.

These old radios are not terribly difficult to restore with a good eye, a steady hand and a hobbyist soldering iron. A couple of photos of the inside of this set would have been a lot more helpful than several of the exterior. The burnt deposits on the underneath are a concern, at first glance, as it indicates something may have become hot inside, possibly just a wax capacitor. Take the lid off and post some more photos.
Generally, the main electrolytic filter capacitors will definitely need replacing (they are polarised and higher voltage) and better, modern caps are easy to source. You may as well replace all the paper, lower value, non-electrolytic capacitors also and they are easy to source. Valves often are not the problem unless damaged by faulty filter caps but can be obtained without too much difficulty. The vibrator power supply (if fitted) may be harder to get but not impossible. An AC to 6V DC converter power supply to fire the radio up won't take up too much room in your home.
Keep one hand in your pocket once the power is on if you are testing the radio with a probe.
www.justradios.com are a good source of components and help.

Thanks @corbinder89, I agree. Gutting the old radio would be my absolute last choice. I'm more in the camp that I'd rather keep my current radio even if I can just get it to play some static fuzz so I can have some old tunes on my phone. Sounds goofy, but at least I'd keep the truck with its 'original' parts.

I'm sure Chicago has some local radio heads, so I'll go that route if I end up needing parts.
Thanks!

@chelty110, I've got all three of those, though the extent to which my eye is good is arguable . I've added some more photos that include the inside.

Is it possible the goop was an adhesive to keep it from rattling against the dash it was bolted against? It scraped right off (see the new photos).

I've only ever used a soldering iron for piping and connecting wires, so I'll have to learn to remove old solder and clean electrical components (fingers crossed!).

Thanks for the tips!

Those new photos indicate much more about your radio! I still think the "goop" is most likely wax that has melted from an overheated capacitor. I have seen much worse condition valve radios that have been easily restored. I would definitely replace all the capacitors before you try powering the radio up. Remember the electrolytic caps are polarity dependent, and will not work if you get that wrong, but not the lower value non-electrolytics. Buy axial capacitors (wires at each end) and replace the capacitors one at a time so you don't forget their placement or any direction of polarity. Your radio's schematic will tell you what you need. Check the other side of the chassis (where the valves are) for any caps that may be hiding there too. Resistors are generally more stable so probably won't need replacing but look for any that are obviously burnt out. They have colourbands on them to indicate their resistance and their size normally indicates their voltage but go higher if you're not sure. Replace any of those lightbulbs that are burnt out. Depending on your power supply and aerial, this may be enough to serenade you to your heart's content (and be a satisfying achievement!).

Cool radio. I'm with chelty110 - replace all the caps before you try to power it up or you might blow something harder to replace. I've done some repair on old electronics and it's usually the caps. The rest is usually pretty robust. Check out "Mr. Carlsons Lab" on YouTube. He's a tube radio genius!

Hi folks,

Does anyone know what steps I'll need to take to install my 6v radio into my 12v (converted) pickup? Or will I need to make changes to the radio itself (e.g. increase capacitor/resistor sizes)?

I've got the radio all cleaned up, am about to begin repairing the radio, but I wanted to figure this out first in case there's any changes I need to make to the internal radio components.

Many thanks!
Nic

Install a electronic (solid state) voltage convertor with enough current capacity to handle the "in rush current when the radio is turned on and the tube filaments are cold. You want something that can take an input voltage to 15 and provide an output in the 7.2 to 7.6 volt range. There are plenty for sale on E bay.
I'd guess you need something in the 5-10 amp range to be safe.

Install a electronic (solid state) voltage convertor with enough current capacity to handle the "in rush current when the radio is turned on and the tube filaments are cold. You want something that can take an input voltage to 15 and provide an output in the 7.2 to 7.6 volt range. There are plenty for sale on E bay.
I'd guess you need something in the 5-10 amp range to be safe.

Great, thank you!
Just wanted to be sure I change any necessary internal parts when I dig into it.
Appreciate the info. And apologies - looks like you posted some of this info above already, and I missed it.
Have a nice evening!