Questions regarding broken CRT lead

[Skywaffle]

What a heartbreaking experience. I will try to clean up the area and see if I can expose any of the wire. It appears that there is a bit of oxidation at the base of all the leads.. But only the one managed to break (or maybe burned up; the glass stub you speak of that can be ground down is chipped.)

Going into the project, I initially never had much hope with the initial condition of the CRT. But things were really looking positive after the rejuvenation. It was a joy to watch for the brief time I could.

[Jeffhs]

Originally Posted by Skywaffle

What a heartbreaking experience. I will try to clean up the area and see if I can expose any of the wire. It appears that there is a bit of oxidation at the base of all the leads.. But only the one managed to break (or maybe burned up; the glass stub you speak of that can be ground down is chipped.)

Going into the project, I initially never had much hope with the initial condition of the CRT. But things were really looking positive after the rejuvenation. It was a joy to watch for the brief time I could.

I agree with Electronic M's assessment of your situation. I hate to say this, but unless you can find some way to expose enough of the broken lead to solder to it (not likely, given how short it is), and the very real possibility of ruining the tube if anything goes wrong while you are working on it, your CRT is junk and must be replaced. I would try to find a good used CRT from a junked set. In this age of flat-screen TVs, it may not be easy to find a replacement for any size CRT, as these tubes are becoming very scarce and are all but impossible to find new--needless to say, no one makes CRTs anymore. I am not familiar with the CTC20 chassis, so I don't know if it uses a round or a rectangular CRT.

Further, if you rejuvenated the tube with a CRT tester, bear in mind that any improvement you may notice won't last long, so it is probably just as well that you will have to replace the tube. Rejuvenation is usually done only to restore a CRT to usable condition (albeit dim) until the tube can be replaced; it is not meant to be a permanent fix. The tube will eventually dim again, at which point it must be replaced. CRT brighteners were often used in the 1950s-'60s to extend the usable life of dimming tubes, but again, this was only a stopgap measure and usually resulted in a dim CRT again within months; the only solution in this case was either to replace the tube or the TV.

[Crist Rigott]

See reply #218.
http://www.videokarma.org/showthread...master&page=15

[Skywaffle]

This tube is a round 21fjp22. The TV had a brightener on it when I had acquired it, but would not produce much of any kind of image initially. On the tester none of the guns would show any readings until the rejuvenation was performed. The difference afterwards resulted in a picture that was very impressive in a lit room (compared to an extremely dark unfocused looking picture in a dark room). I suppose I had hoped maybe this would be a fairly long term fix.

Originally Posted by Jeffhs

I agree with Electronic M's assessment of your situation. I hate to say this, but unless you can find some way to expose enough of the broken lead to solder to it (not likely, given how short it is), and the very real possibility of ruining the tube if anything goes wrong while you are working on it, your CRT is junk and must be replaced. I would try to find a good used CRT from a junked set. In this age of flat-screen TVs, it may not be easy to find a replacement for any size CRT, as these tubes are becoming very scarce and are all but impossible to find new--needless to say, no one makes CRTs anymore. I am not familiar with the CTC20 chassis, so I don't know if it uses a round or a rectangular CRT.

Further, if you rejuvenated the tube with a CRT tester, bear in mind that any improvement you may notice won't last long, so it is probably just as well that you will have to replace the tube. Rejuvenation is usually done only to restore a CRT to usable condition (albeit dim) until the tube can be replaced; it is not meant to be a permanent fix. The tube will eventually dim again, at which point it must be replaced. CRT brighteners were often used in the 1950s-'60s to extend the usable life of dimming tubes, but again, this was only a stopgap measure and usually resulted in a dim CRT again within months; the only solution in this case was either to replace the tube or the TV.

[Electronic M]

Originally Posted by Skywaffle

This tube is a round 21fjp22. The TV had a brightener on it when I had acquired it, but would not produce much of any kind of image initially. On the tester none of the guns would show any readings until the rejuvenation was performed. The difference afterwards resulted in a picture that was very impressive in a lit room (compared to an extremely dark unfocused looking picture in a dark room). I suppose I had hoped maybe this would be a fairly long term fix.

BTW if a CRT has not been used for a few years the cathode will act as a getter and that will coat the emissive surface in crud that blocks emission....we call it the CRT falling asleep. When a CRT is asleep a rejuve is a dangerous way to wake it up (you can burn off the emissive surface along with the crud covering it). The best way to wake up a CRT is to let it sit on the tester in emission mode for as much as an hour ( check for improvement every 15 min) if it doesn't Improve or barely improves increase the.heater voltage to 1.4x it's designed value and repeat the process, THEN if there's still no life or much less than a usable value you can try a rejuve.

Rejuvination is risky use all safer measures first.

[old_coot88]

Originally Posted by Electronic M

Rejuvination is risky use all safer measures first.

Agree 110%. Rejuv only after all other measures (including CRT brightener) have failed. Learn't that the hard way many moons ago.