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Old 11-27-2016, 03:08 PM
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etype2 etype2 is offline
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Join Date: Mar 2010
Location: Valley of the Sun, formerly Silicon Valley, formerly Packer Land.
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Quote:
Originally Posted by Kamakiri View Post
I managed to pick up some pretty complete Thordarson Meissner, Miller, Stancor, and Workman parts catalogs recently, so we might as well put them to use

If you have a set that needs a part and you need a part number, post it here and I'll do my best to look it up. Model numbers, chassis numbers, and OEM part numbers help out quite a bit in finding the correct applications.

If you have a part but don't know what it fits, I'll do my best to ID it.

Most of my catalog listings end around 1963 or so, but I'll do my best....
Your comments, suggestions much appreciated.

Mike Doyle is helping me restore my RCA 21CT55. Some of you may know him.

The RCA Part number is 78987. It is described in the parts list as the 43.5 MHZ link transformer L2. The parts list does not describe it as also being one of the 41.25 MHZ traps but it states that on the schematic and also in the alignment instructions. It is in fact, both the link and the trap.

Mike found a problem with the first stage of the I.F. strip. The 1rst I.F. grid transformer (T106) does not tune properly. There are 2 cores in it, one for the top and one for the bottom part of the transformer. The one on the top does not tune. He suspects that the powdered iron core is sitting in the bottom of the coil and has become separated from the screw that is normally attached to it and positions it in the coil core. This will be a very delicate piece of surgery. The transformer will have to be removed from the set, disassembled and examined. There are 2 possible scenarios here. Scenario one is that he can successfully repair the coil and scenario two is that he cannot. We will not know until we "go" there. If we cannot then we will have to build a circuit that will take its place using newer materials possibly from a newer chassis. Theoretically, this stage could be mostly eliminated since there are traps of the same frequency in the last stage of I.F. to do the job.The purpose of the 41.25 MHZ trap is to trap out the adjacent channel sideband and since I will be using a modulator to view images it makes this issue a lot less critical. But we really want to do this right and fix the transformer if we can. It is hard to say when this actually happened. It could have happened on its way across the country while in the truck or it could have been that way for many years and picture quality was unknowingly sacrificed. Either way, we are very happy to have found this problem. Now we have to figure out how to deal with it.

We are reaching out to this community. Your opinions, is this doable, or dose anyone have a replacement?

Thank you in advance.
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