Now that the intro is out of the way, its time to dig into the restoration. Almost all radios made from the 1930's and upward used capacitors made of wax, cardboard, and aluminum foil. Prior to the 30's the capacitors were more solid state. Its not unusual for me to find radios from the 20's that still work great. But when the depression hit radio manufactures cut costs. Capacitors were fairly expensive to produce and to cut down on costs they started making them out of bees wax and cardboard. It worked but after sitting around for 60-70 years they tend to dry out and thus leak. About 70% of the radios I get make a loud buzzing sound when warmed up. That's because the capacitors, which are used to regulate the voltage and to filter out feedback for the vacuum tubes are now shot so the radio won't play and instead just buzzes. Its best to replace all of the capacitors anyway.
So the first step is to dismantle the radio. Back in the good ole' days radios were meant to be repaired. Thus they are easy to take apart. The knobs are held on with set screws. The chassis is screwed through the bottom of the cabinet. Once those are removed the entire chassis slides out the back. This radio has a large speaker. Since the cabinet is going to be refinished the speaker needs to be removed too. A plate covers the back of the speaker where the wires connect. Since the wires are now faded to the point where their colors look the same I try to mark and describe their location. I remove the screws holding the speaker wire terminals to the speaker and mark their positions with tape.
Now I remove the entire chassis. As you can see the components are all gigantic considering this is an AM radio ( No FM) and a modern radio would easily fit inside just one of the tubes several times. The chassis weighs well over 30 pounds.
This is a highly sophisticated radio ( for the time it was made) It not only has AM, but shortwave as well. That means it picks up international stations. I am also impressed with some of the unusual engineering that was built into the piece. All the radios I've ever seen use a sort of pulley and cord tuning setup. Simply put, a string is run from a knob to a drum that turns the tuning plates. This radio uses an unusual spring-loaded ball bearing pressed against a roller that is connected to a gear mechanism. In other words its a "direct drive" tuner. Also, if you switch bands a piece of plastic with the band designation pushes past a light bulb that back illuminates it so the user can see what band they are on.
Moving forward, I ran into a problem. On most radios the capacitors themselves are marked so you can read their values. They are usually easy to replace. The way it works is if you had say- a .25 MFD capacitor rated at 200 volts, all that means is that it the capacitance rating is .25 MFD and it will take a max of 200 volts. But you can always just buy whatever replacement you need as long as it is more than 200 volts. I usually buy 600 Volt bulk capacitors. The problem is that NONE of the capacitors are marked. What a pain in the rear. Luckily there are guys online who have taken the time to painstakingly scan old out of print repair manuals and schematics. A lot of these are very detailed. Unfortunately none that I can find are good enough quality to read. So I had to buy some high quality versions from a supplier. It was $6.
But basically if there are no markings on the capacitors, you'll need to identify them via a schematic which will tell you all the values. So the next step will be to translate the schematic to modern day replacements. The good thing is that modern capacitors last forever and they will be hidden under the chassis. You can also buy NOS or new tubes. most believe it or not made in Russia or China. They're not that expensive. With new tubes and capacitors a radio like this would play as good as new. Not bad considering its 75 years old.
