How to Replace Resistors in Antique Radios
Everything gets old. Replacing the resistors in an antique radio can make it work a lot better. In some cases, such as a short or open resistor, it can revive an antique radio that is dysfunctional. However, when working with antique equipment, it is important to proceed in a logical and careful manner. Some old styles of resistors, such as dog bone resistors, are no longer being manufactured, and markings on old technology may have different meanings than they do today.
Other People Are Reading
Instructions
-
-
1
Find each replacement resistor and make sure that you know where each resistor goes. Finding old resistors can be difficult, so the modern cylinder type with the colored bands can be substituted. Old resistors did not always use the modern colored band system; often, the value was simply stamped into the resistor. These old marks can be tricky. On antique resistors the letter "M" often means 1,000, not 1 million. This was consistent with "M" for "Milli." Another mark on old resistors that is confusing is the use of "W" for "ohms." A schematic for the specific radio you are working on will provide the best information about resistor values. Antique radio schematics are available on the Internet. If you do not have a schematic, do a thorough exploration of the radio and mark down the value of each resistor.
-
2
Join modern resistors serially or in parallel to obtain the desired resistance. You might not be able to find a 450 ohm resistor, but you can get the equivalent resistance by attaching a 50 ohm and a 400 ohm resistor in series. You may not be able to find a 33 ohm resistor, but you can get the equivalent resistor by attaching three 100 ohm resistors in parallel.
-
-
3
Remove the old resistors from the radio. For each resistor, clamp something like a clip of clamp (as a heat sink to protect the radio) to the terminal that the resistor is attached to. Heat the solder and remove one end of the old resistor physically. Do the same with the other end of the resistor. Clean off the terminals. Physically attach each end of the new resistor in place with the needle nosed pliers. Make sure the heat sink is in place and solder both ends of the new resistor in place.
-
1
Tips & Warnings
Consider adding a fuse to your radio. It could be on the inside so it doesn't show. Antique radios sometimes do have shorts, and a short can lead to something in the circuit getting hot. It is a lot better to blow a fuse than to have the radio burst into flames.
Vacuum tube radios are dangerous. Not only is the 120 AC that comes out of the wall sent to several places on the radio, the plate circuits of the tubes can develop 400 volts or more.
References
Resources
- Photo Credit vintage radio and gramophone image by jovica antoski from Fotolia.com
