15GP22 rebuilding update...

[Pete Deksnis]

Here's the latest info in the seven-year-long effort:

http://home.att.net/~pldexnis/input/news.html

[kx250rider]

That's some exciting news! I hope that it works out in the long run. The big stumbling block has been the rusting of the metal flange, causing cracking/leaking of the glass-to-metal seals.

Charles

[sweitzel]

Wow that IS good news! Question, how many "dud" 15GP22's are known in existence?

[John Folsom]

One would expect there are at least as many dud CRTs as there are sets (approx. 127 known sets). Some of these set have known good CRT, but I suspect the majority have duds. And I suspect there are quite a few "loose" duds out there. But of course, it is not known how many of those can be rebuilt. The ones still under vacuum are good candidates, and will be the first ones attempted. The "leakers", those that are full of air, are an unknown proposition. It may turn out that most, or even all, of the leakers cannot be rebuilt. Stay tuned.....

[Sandy G]

I'll prolly never have a CT-100, but this is REALLY good news...We don't realise it now, but these things might be viewed as precious artifacts in 100, 200 years...

[kx250rider]

Originally Posted by sweitzel

Wow that IS good news! Question, how many "dud" 15GP22's are known in existence?

I wouldn't be surprised if it's 2:1 against CT-100s. I've had and sold/traded off at least a dozen dud 15GP22s, and just about every CT-100 owner I know of has at least a couple of spare bad CRTs. Not all of them will be usable though. About half of the ones that I know of which aren't positioned in a TV (are stored on their faces), have phosphor blotches

Charles

[John Folsom]

Charles,

Ummmm phosphor blotches.... that sounds bad! I have a few ugly 15GP22s, but no phosphor blotches.

[kx250rider]

It seems that when the vacuum has failed, and the tube sits neck-up for many years, the phosphor gets dark angular blotches. Now even the one in a CT-100 that I have is doing that, and I was told that the CRT in that one was confirmed non-vacuum as of 1980. That set spent 15+ years in a garage, but has spent the past 15 years since then in an indoor climate. So maybe the phosphor starts taking on humidity or something after a period of time, more so when the tube is on it's face?

Charles

[Pete Deksnis]

Inspected two 15GP22 duds under a strong light and came up with zero blotches... until I used a magnifier and found a sea of mini 'blackheads' that are much tinier than a phosphor dot. Can't say for certain that it isn't contamination during manufacture, but it doesn't quite look like that. The other dud doesn't have the blackheads. However, the thick glass faceplates are full of tiny air bubbles and bits of grit; just focus your magnifier inside the glass to see it. And although I can't quite perfectly focus my magnifier on a good phosphor dot plate (because of the CT-100's safety glass) they do seem to be 'blackheads' free.

[kx250rider]

These blotches are larger; about 1/4" to 1/2" in various geometric shapes. They start as a VERY slightly faded blotch, then grow darker over the years while staying the same size. The ones in the CT-100 aren't pronounced enough to see in a photo, or I'd post... Maybe someone with a worse case could post?

Charles