RCA CT100/21CT55
Fine Tuning Knob Repair

The fine tuning knob on the 1954 and 1955 TV sets was a very poor design. The throat of the knob is very fragile and tends to crack and break quite easily. As a result I have never seen an example of this knob that hasn't had cracks and pieces of the plastic throat missing. As a result I devised a method of repairing these broken knobs and improving them so that they will never break again under normal usage.

The first step is to remove the broken throat from the knob, as can be seen in this photograph. The knob on the left is the way the knob was when I got it with the obvoiusly broken plastic throat. The knob on the right is how the knob looks after I remove the broken throat. Note: that I leave a shoulder of the original plastic throat so that I can attach the new throat to the knob.

This next photo shows the new aluminum throat that I custom machine in my machine shop. One end of the part has a knotch cut into it to mate with the bakelite shaft on the tuner. The other end of the part has a diameter that fits over the remnant of the plastic shoulder on the knob.

The custom machined aluminum throat is then attached to the plastic throat on the knob using epoxy glue. The aluminum throat is machined for a very close fit so that when the knob is mated to the new aluminum throat, very good alignment is achieved.

Repaired knobs can be purchased in the For Sale section of this web site.