21CT55 Screen-Shot Test

[WISCOJIM]

Picture is not working.



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[Electronic M]

Originally Posted by WISCOJIM

Picture is not working.



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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]

[Tomcomm]

[Tomcomm]

Mine Is Blured

[old_tv_nut]

blurred

[WISCOJIM]

Blurred and watermarked.

[kvflyer]

Photobucket.... What a disgrace...

[miniman82]

Originally Posted by kvflyer

killed 2 unobtanium flybacks.... What a disgrace...

Fixed that for you.

[Tomcomm]

I don't get your post. What are you trying to say? "Fixed that for you."

Something about me destroying two flyback transformers? Get A Life!

My 21CT55 blew its original FBT March 21, 2010 due to old age. That's one.

I replaced it with a new RCA CT20 from Mouser which didn't work. Seems it
had no connection to it's CRT HV socket! I fixed it and recoated the entire HV
FBT in silicone. It worked great until the coating failed and arched over to
the HV cage last March. I had other things to do so the 21CT55 just sits there!

I offer no apologies. Tom

[miniman82]

Originally Posted by Tomcomm

I don't get your post. What are you trying to say? "Fixed that for you." Something about me destroying two flyback transformers? Get A Life!

My beef with you is that your ham fisted attempts to 'improve' and hack parts into a historically important chassis are decreasing a finite supply of irreplaceable parts which only seems to end in disaster every time. I've already made my feelings known before this thread was 'cleaned up' by mods in the past, but it seems nothing has changed. You might as well be melting down 15GP22's to turn them into Trinitrons, they objectively have better picture quality so let's get rid of those pesky old CRT's right?

My 21CT55 blew its original FBT March 21, 2010 due to old age. That's one.

Revisionist history!

You melted them down by running them outside their design specifications in an ill fated attempt to make some unverifiable 'improvement' in picture quality. Apparently your definition of quality is no picture at all... You were told, and continue to be told by very knowledgeable people that what you are doing is not only wrong but dangerous, yet you persist. I can only hope I don't come here reading about your obituary one day.

I'm petitioning this thread to be closed, by allowing it to continue this body is condoning your actions. I won't.

[Tomcomm]

This thread started over 7 years ago and has received over 237 replies.
My 21CT55 is inoperative, awaiting repair of it's CT20 FBT horsehair ultra hv
wire, as reported. I'm presently working on my classic car hobby. Checkout
VideoKarma "Things With Motors", "Olds V8 Healey". I'm not easily intimidated.

[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.

[Tom9589]

The absolute maximum spec is just that - the maximum that a device can be subjected to - no safety factor here. The nominal 25KV spec that RCA specified for this TV should have some safety margin associated and 10% is not a bad estimate.

30KV is 20% over the nominal operating voltage of 25KV. Considering the date of manufacture of this TV, there were not many provisions for shielding the repairman or viewer from x-Rays. Consider the safety provisions of later years such as higher lead content of the tube envelopes and even lead shielded HV rectifiers and these are for TVs operating at 25KV.

If you continue to work on this TV or watch it in close proximity running at 30 KV, you may end up like Homer Simpson in post #5 of this stream:

http://www.videokarma.org/showthread.php?t=272531

No emotion here, just common sense.

[Electronic M]

Pretty sure I ran mine without the HV reg for a few seconds....it arced to the HV cage when the HV came up and I shut it down as quickly as I could...

I suppose I could run that test for 5 sec After HV comes up from cold and it would probably not hurt for that brief of a run, but more than that is a risk I'd never take.

Nominal line voltage when these were new was 117V, and much above 120V was rare...the engineers that made this would have advised contacting your utility or adding a stepdown transformer to reduce line voltage if you had 130V at your outlets in 1954....heck this set draws enough current that copper losses in household wiring drop the voltage at the outlet a bit when one of these is running so you would have to have an even more implausibly high line voltage with nothing major plugged in to have 130V with it on.
Also engineers assumed in absolute worst case scenarios for the support life of the set (10-20 years after production) if you blew the fly a new one could be ordered.... that time is passed so we should be running these for longevity rather than the bleeding edge of what the design is capable of.

These sets performed excellent when perfectly adjusted to stock specifications. Going beyond stock in a manner that increases the risk of destroying unobtainable parts on a set that is highly desirable and of which only 40 examples are known is not going to be met with encouragement (and acceptance may be a stretch) from a community dedicated to preservation no matter how hard you try to justify it...

Increasing the HV only really does 3 things: 1.) Increase the brightness, 2.) Reduce width and height of deflection a bit, 3.) Change optimal focus and gun bias setting points. 1 should not be necessary since you are using a brighter later production all glass tube. The other 2 are not necessary either and can be achieved with minor adjustment to the deflection circuits and such.

With some effort you should be able to achieve an identical picture a tad less bright at the correct HV spec... rather than turning it up to 11 to try and somehow brute force better picture out of it, why not instead challenge yourself to dial it in to look right at 25-27KV and maybe reduce your room lighting so it seems just as bright?

Granted with the incorrect flyback and other random modifications maybe there is no sense trying to make it reliable anymore and you have introduced design changes that doom it to failure...If that is the case and you don't mind it dying irreparably by all means run it till it dies. Given you've held on to it this long one would imagine you'd want to see it still around after you check out, but what you do with it is your business.... rubbing what, to everyone else here, is dangerous mis-treatment of a rare piece of history in our faces when we have repeatedly explained this and tried to convince you not to, comes across as trolling at this point.

No emotion is present in this and no insult is meant just my appraisal of the situation.