Join Date: May 2017
Location: Bossier City, Louisiana
Re: radio repair for dummies??
The electrolytic capacitors usually have dried out and lose their capacitance. If its just a single cap on the board, replacing these is usually easy if you can still read the required capacitance and voltage on the part. Mouser Electronics and Digi-Key will have these piece parts for cheap - shipping will be much more than the value of the parts.
Finding the defective cap on the board is usually easy. As long as we are discussing radios WITHOUT vacuum tubes, these are all low voltage radios with little chance of electrical shock. For the radios without vacuum tubes, it is often possible to detect the bad capacitor simply by placing your finger on the leads of each capacitor on the printed side of the board - the flesh of your finger supplies a little capacitance. The sound out of the speaker will sometimes return temporarily under these conditions while your finger is in place. Note the values on the capacitor, procure it and then carefully remove the old one. Install the new one CAREFULLY noting the polarity on the side of the capacitor. Get this wrong and your new cap will get hot, bulge out and explode like a small firecracker.
The problem is the multi-value capacitors in a metal can within the radio. Those parts are tough to find that still work and have also not already dried out. These radios are scrap value to most of us at that point unless you want to send it to a true professional radio restorer. They might have the parts or are willing to do the more tedious re-design work to find modern alternative parts.
All bets are off for vacuum tube radios. Their voltages can be deadly unless you are skilled at bleeding off stored power in the capacitors that still store energy.
1970 El Camino under Reconstruction - 5.3L LS VORTEC Engine and 4L60E Transmission