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Here is the latest on the restoration of the 21CT55, CTC2B Oct 7, 2015 All wax caps have been changed out, except those mentioned below.
Well, I powered it up again on the bench, although it still needs a few more caps, 6 in total, 2 are already ordered from MCM. I have sound, vertical, high voltage, and video waveform (on my scope at all three CRT grid connections), and voltages are within range at the CRT socket proving that the set should produce some kind of picture or at least a raster, when I get it hooked up to the CRT. When I first powered it up, there was a buzz and a wisp of smoke somewhere in the audio section. After trying it again, and not being able to locate what got hot, sound came on just fine. I can get plenty of high voltage, although if I push any more than about 22kv, it sometimes arcs and snaps like a firecracker. Not sure where it is arcing. Flyback runs pretty warm, almost hot, after being on for 15 minutes or more in the center part of the flyback. Current being drawn by the horizontal output tube is normal, even a little on the lower side, 185ma, so that shouldn't be the cause of the warm flyback. I also still need a couple more tubes that check bad, a 12BH7, and a 6LN8. None of the tubes or capacitors that are still needed should affect the flyback. Power supply runs right at the rated 400 volts with 115 volt AC line. I want to get the other caps and tubes in there before I figure out how to hook it up to the CRT and still be able to service the chassis. I can either sit in on top, or on top of something right behind the set. I also still need to order a much longer piece of high voltage wire to hook up the set outside of the cabinet. Sams indicates that the high voltage should be at 25kv. I still wonder if that is higher than it needs to be. My biggest concern is that the flyback will be OK. If it goes up in smoke, well, finding one is almost impossible. I still have high hopes for the old 1954 set, as I have lots of time and $$ into it.
Today's update: Oct 08, 2015. Powered it up again, no snapping of HV at 24KV, so may just be moisture or dirt. Found the problem with the buzz and smoke up by the audio section. It was just a pinched wire, which runs upfront by the service adjustments. I don't think any damage was done. Flyback will get quite warm, even though the Horizontal output tube current is within the normal range. However the waveform at the grid of the horizontal output, (the sawtooth waveform) is flattening on the top. Picture attached. I noticed there are adjustments for wave shape, etc in the Sams, so I'm assuming that will take care of it. The waveform may be what is causing the flyback to get warm, mainly in the center of it close to the core of the transformer. The large ring for the high voltage winding remains cool. Yoke, convergence yoke, and magnets are ready to go back into the set. I have the possibility of getting a CRT test jig. An RCA. I'm not sure if I can use it with this set or not, but could also use it on my CTC9, and others. I am encouraged, I'm just taking it a little at a time.
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