RCA CTC4B "Gainsborough" picked up in San Francisco

[ohohyodafarted]

Chris,

Just goes to show you learn something new every day. I had always wondered about the 3 different CTC4 chassis. I did some investigating and in one of my RCA service bulletins I found a chart defining the 3 different chassis. The 21ct660u and 661u in the two low end Seville and Haviland models, used the early production CTC4 chassis. The 21ct662u Director, used the CTC4A. The 21ct663u Cheltenham and 21ct664u Gainsborough used the CTC4B.

There are a fair number of circuit differences, mostly in the color circuits, between the CTC4 and CTC4a. I don't have a CTC4B RCA schematic so I am not sure where the circuit differences lie in the CTC4B version.

Unfortunately I got my Cheltenham without a chassis. It was just a gutted cabinet. I have a CTC4 and CTC4a chassis to work with but I do not have a "B" version. And what is worse, the CTC4A I have has been canabilized so I am not certain which direction I will proceed. I am leaning toward rebuilding the "A" chassis but that will entail finding a pile of spare parts that are missing. Clearly the CTC4 early version is not correct for a Cheltenham.