Heathkit GR-900 Build Thread!

[jr_tech]

Originally Posted by N2IXK

I have serious doubts about the safety of tubes that have undergone the standard cat removal procedure. The whole purpose of that resin was to effectively form a glass/resin/glass laminated panel, similar to automotive safety glass. Without the resin layer, it is just an unprotected CRT behind a second sheet of non-safety glass (the reinstalled faceplate). At least the older sets actually used a laminated glass safety panel in front of the unprotected CRT. The faceplates on laminated tubes are just tinted or frosted glass, which would only add to the shrapnel from an implosion if not bonded with the resin.

Obviously CRT rebuilders must have had a way to remove and rebond these faceplates properly when rebuilding tubes, as the resin would never have stood up to oven bakeout. Does anyone know how this was done? It isn't addressed in the excellent film made of HawkEye's rebuilding process over on the ETF site. I imagine that it takes some special setup (like vacuum impregnation) to ensure no trapped air bubbles in the resin. Clear 2 part urethane casting resin is available from several suppliers, and would probably be a good substitute for the PVA that was originally used, if a way was available to get a void-free fill.

In this post, I described a process that I have observed:

http://www.videokarma.org/showpost.p...11&postcount=2

jr