I have had to make several contacts for the Zenith Royal 500 transistor radios, and I’m only on the second radio refurbishing. Most of the problems have been mechanical – worn volume controls, tuning capacitor shorted because the screw for the trimmer capacitor was grounding, and bad battery contacts. The battery contacts have been horribly corroded, to the point where they are disintegrated or fall apart. There was nothing to repair. So I have been replacing them with sheet steel I cut from a tin can lid with scissors.
The first two I made were single thickness, and work okay. The third one I made this morning by folding the sheet in half and flattening it, then bending it to shape and drilling a hole for the screw. The spring is twice as strong but it seems to work okay. Since it is two layers, the battery liquid will go between the layers and quickly corrode it. It will have to be replaced even more often. But these radios were made around 1960 and have lasted more than 50 years, so I don’t think that’s a big problem.
I made this double thickness contact in the wrong order. The right order is the following.
Cut the steel lid a bit wider than the original contact. The excess will be trimmed off later. It should be about 2-5/8 inches long.
Use a hammer and pound the sheet flat on a smooth, flat surface. File off the sharp edges. Then using sandpaper, sand off any paint or varnish.
Measure and fold the sheet in half. Flatten with the hammer.
Make the 90 degree bend farthest from the folded end. Then make the 170 degree bend close to the folded end.
Drill the hole for the screw in the 90 degree end. This hole should be slightly bigger than the 2-56 screw. Check the size and trim excess with the scissors.
Before putting the screw in, put the solid copper wire through the hole and solder it to the contact. After it has cooled, secure it with the 2-56 by 3/16 inch screw and nut.
Repeat as necessary. So far I’ve only had to replace the contacts closest to the bottom probably because the battery juice runs downward.
