In the age of satellite technology, many people assume that fixing an old-fashioned radio is as difficult as fixing their high-tech equipment. In fact, most old radios are tube-based and relatively easy to repair. As with any piece of older equipment, replacement parts can be difficult to find. The receiver is the heart of a radio, and the tubes or capacitors are its veins.
Clean the radio. Dirt, grime and rust may be causing part of the problem. Clean the outside of the radio as well as all the parts on the inside. A dry paper towel is all you will need at first. If the radio has rusted chrome, you may need to re-chrome or replace the pieces. This is an expensive task, and you many restorers choose to live with a little rust rather than replace original pieces.
Plug in the radio. This is called "firing up" the radio as many old radios use tubes that need to heat up before use. Check with a voltage tester that the radio is receiving power. If not, the problem may be in old cords that are frayed cracked. A replacement cord may be the only fix the radio needs. Old power cords are the number one cause of radio failure.
Check the tubes. Radios have either tubes or capacitors. If your radio has tubes, they are likely fine. Tubes are vacuum-sealed and last a long time unless the radio has had a piano dropped on it, or a similar mishap. If the tubes are cracked or broken, replace them.
Identify the capacitors. Old radios have either electrolytic (polarized) or non-electrolytic (non-polarized) capacitors. Electrolytic capacitors are prone to failure, and usually replaced during restoration. Non-electrolytic capacitors made of paper are also unreliable and should be replaced. Capacitors made of ceramic or mica are ideal and should not be replaced unless necessary.
Check if the capacitor needs to be replaced. If the capacitor is ceramic or mica, check with an ohmmeter to see if it works. Melted wax around a capacitor can give it the appearance of being squished or melted, but it may still work. If the ohm reader registers activity, you can leave the capacitor even if it is unattractive.
Fix the switches. If voltage is reaching your radio and all non-working parts have been replaced, check that the switches are doing their jobs. If not, switches can be replaced, or re-aligned to connect with the internal parts.
Find a copy of the manufacturer's schematic to help with how the parts should fit. For a car radio, remove the front plate and check that wiring is correct.