Quote:
Originally Posted by Harold Deppe
Hi all,
This is my first post to this very interesting site.
I recently started restoration on a CTC-16 with a rebuilt 21FJP22.
The CRT looked very good on the checker and when fired up produced a good picture with excellent gray scale tracking. One night after watching it for about an hour I shut it down and went to bed. Two days later I decided to work on some issues with the convergence board. I was horrified to see the gun assembly hanging limp. During cool down, the contraction of the glass must have caused a weakened neck seal to let go. Up to this point, it was a great tube with only the slightest hint of delamination of the face plate (barely noticeable with high brightness).
Anybody know of a source of 21FJP22's?
Harold
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I've seen this happen on 2 sets, and I'm blaming the blue lateral magnet, but only if that's where the break occurred. Think about it folks, the magnet is held by a brass strap (bad), which is then secured by a steel spring wrapped around the neck, worse!! When that assembly gets moved around on the neck, especially one that's dirty, it causes minute scratches. Enter heating & cooling (expansion & contraction) due to the filaments, and anyone who has cut glass in the past will know what's bound to occur next: a crack. The crack will form in a perfect circle around the neck, and the neck will fall off after loss of vacuum. Symptom on one set was dim & blurry picture. I then saw the ring crack under the BL magnet. I immediately slid the mag forward, cleaned the glass with Windex, and applied a bead of silicone. Fixed. I let the set operate for a few hours, and the getters mopped up whatever air leaked in, and was once again rewarded with a beautiful picture. I know that set was watched for a least 1.5 - 2 years before something else failed, and the set was pitched. Yes, I wish I still had that set, but that was 29 years ago, and nobody wanted roundies back then. The crack did not form at a neck splice, as these were both OEM tubes.