21CT55 Screen-Shot Test

[Tomcomm]

HV-cage-rebuilt by Tom Schnerk, on Flickr

[Tomcomm]

b!00000119 by Tom Schnerk, on Flickr

[Electronic M]

With your second CTC-20 flyback, make sure NOT to run it above 25KV. 25KV is what it was designed to run at, and RCA tended to run their flybacks at the top end of what they could survive...Pushing it beyond that is asking for failure.

[Tom9589]

Tom, why did you apply silicone to the first CTC20 FBT?

[Tomcomm]

The HV rectifier plate socket on the transformer top was open circuited. Should have measured around 600 ohms to the horizontal driver plate. Since the FBT was obviously never soldered in I elected to attempt a repair rather than send
it back to Mouser. This entailed removing the plastic coil covering and resoldering the very fine "horse hair" wire from the coil ending to the rectifier socket. It then measured 630 ohms which was about right. I decided to recover the coil with Permatex Ultra Blue instrument grade silicone sealer to protect the very fine coil wire. This fix worked fine for all of my "Performance Enhancement" experiments for the last 8 years as well documented in this VideoKarma thread.

[Tomcomm]

Point of interest: What does an unmodified 21CT55's CRT anode voltage run with cutoff screen and the HV regulator pulled, with 130V AC Line input? Anyone?

Seems this worse case scenario must have been envisioned by RCA engineers before they got it released to production. What sort of catastrophic failure of non-tube replaceable parts would they tolerate? The CRT and FBT for sure are major items of concern and must be specified with at least 10% safety factor.

My 21FBP22A CRT is spec'd at 27000 volts max. My 21FBP22A CRT is set to run at 30000 volts with 120v AC or 11 percent over max spec for demonstrable maximum picture quality. I accept this risk vs performance tradeoff.

[Electronic M]

Most makers assumed that a set would not be running for a long time in failure mode...just because you can run an engine for a couple of minutes with no oil or coolant in it without it burning up doesn't mean it won't if driven in that state for a prolonged period.

You've already seen the original and 1 replacement burn up. Shouldn't that tell you to dial it back a bit? Even 3-4KV (lets say a tech had a HV probe that was 1-2KV off and set it for 26-27KV) less than you've been running it at will have only very minor effect on brightness, sweep and general image quality and will be at least reasonably close to factory specifications. Even before the X-ray alarmists many makers in their service literature stressed proper HV adjustment. New flybacks don't grow on trees; why not cherish what may be the last one you can find?

[Tomcomm]

[Tomcomm]

[freakaftr8]

I'm getting warnings on bandwidth limits. I dont use PB anymore and wont let me login. Lol

[Tomcomm]

Copy of 39 by Tom Schnerk, on Flickr

[Tomcomm]

[WISCOJIM]

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[Electronic M]

Originally Posted by WISCOJIM

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On my smartphone I don't get the bluring and water mark*. They either don't do that with smartphones or they only water mark photos going to IP address associated with current and former customers of Photobucket.

* Noticed this effect with photos in old threads I posted....the computer I posted them with gets the water mark and others don't...some other members photos get watermarked on my upload PC too.

If I had time and motivation I'd make my own photo hosting server, delete every picture on my Photobucket and Flickr so they could not make any money off it and be done with the whole mess.

[Tomcomm]

Mine Is Blured