Bringing new life to an old tube radio

I recently purchased a 1950 Arvin AM/FM tube type radio from an antique store. the radio wasn't in too bad condition for its age and after testing it before i bought it, the radio sounded great and everything worked on it (except the FM side, but thats for a later instructable). so i splurged a whole $25 for it and brought it home. the next thing that I decided to do was make this radio have a more updated presentable look rather than the old vanilla color it had, so i went and got some Krylon spay paint because they are known for having good plastic material related paint.

materials i used to do this:
1 roll of masking tape
some newspaper
1 can of Krylon fusion hammered finish (dark grey in color)
1 can of Krylon metallic finish spray paint (bronze w/ metal flakes color)
some toothpaste for polishing
toilet paper for polishing

Step 1 Removing the chassis

I removed the chassis which was held on underneath by 4 screws, and also the knobs on the front which just pop off with a screwdriver. there appears to have been some updating done to the chassis some time in the past too. it has a polarized power cord, a newer looking speaker, and tuning dial string which these things i know weren't original to the radio. im not sure if the tubes are original or not, they look really clean and light up well. the chassis has no rust or for that matter dust anywhere on it. the underside is all original caps and resisters and fabric wiring. the antenna on the back works great still.

Comments

[Phil B]

I expect you will replace the paper capacitors one day and will likely vacuum dust from the blades of the tuner. Some things you wrote hint that you are probably aware of those things, even though you did not mention them.

[florlayamp]

yes, although the caps appear fine, i know that they probably dont have their original values anymore so i really do need to change them out.

[Phil B]

I once bought an old Zenith Transoceanic multi-band radio. It worked fine the first time I turned it on. Then I had to replace a capacitor that failed. It worked again. Then another capacitor failed, and so it went until I had replaced all of the paper capacitors. As concerns values, I remember reading that the values of even new capacitors can be off as much as 100 percent.

[dcastor]

Yes, the old paper/wax capacitors do not stand up well to the heat produced in a tube radio. You are lucky they lasted this long.

As for how far off they can be when replacing, it depends on where they are used...for the large electrolytic capacitors (looks like you have one, vertical round can mounted near the middle of the back) Phil B is correct, they can be replaced with capacitors as high as 100% higher than the originals (but not lower). I try to find ones that are as close as possible to the originals because it makes it easier to identify on schematics if anyone else is working on this radio in the future.

The paper capacitors are a different story and should be replaced with capacitors within 20% of the original value (again higher than the original value, not lower). This is because the original caps were not manufactured as precise as modern ones...the margin of error was far from what it is now.

Be careful on voltage ratings...these old radios will have 180 volts DC in some places, so I don't buy anything rated for less than 400V so I can use it anywhere in the radio. A modern cap with the same farad rating is likely not going to be designed to handle this kind of voltage.

[florlayamp]

thanks for the info! that will help out alot in the future when i start really digging into this thing.

[ZoDo]

Great job.

[Sparker94]

You did a awesome job! Jobs that look that good people pay good money for here in Vegas.

[knife141]

Cracks are easy to fix on these old plastic radios. I've had good luck using super glue. First, glue the crack shut. Then build up layers of super glue in the crack. When the crack has been overfilled slightly, sand it flush with the cabinet with 400 grit sandpaper. Apply paint and the crack disappears. Also, I've found it much easier to simply pop out the plastic lens that covers the dial than taping it off. Plus, while the lens is out, it is easy to polish out any scratches.

[knife141]

Oops! just re-read and saw that you did remove the dial lens.

[florlayamp]

actually, i didnt remove the lens, i just removed the dial and the dial background which were attached to the chassis. the lens was riveted to the plastic and i didnt want to break it off so i taped it.