Removing PVA from a CRT - test-drb@ccmp.vtda.org

20 Nov 2018

...

 Date: Mon, 19 Nov 2018 10:41:36 -0800
 From: Alan Perry <aperry at snowmoose.com>
 Subject: Removing PVA from a CRT

 I recently picked up a Rainbow 100. The PVA between the safety glass and
 the CRT on VR201 that came with it has broken down and failed badly.

 I have seen videos and read about removing the safety glass, cleaning out
 the PVA, and reattaching and resealing the safety glass.

 All that I have seen basically sticks the safety glass on at its edges and
 leaves a void where the PVA had been. It seems to me that the PVA was
 providing some implosion protection. Would it work to replace the PVA and
 attach the safety glass to the tube with an optically clear adhesive sheet?
 I have seen that this exists, but have never used it before.

 alan

When we fixed the VR14 at the RICM, we were concerned about the safety
aspects of removing the PVA and just using double-sided tape to hold the
outer glass in place. We bought a thin sheet of Lexan at Home Depot, put
the outer glass on a cookie sheet with the outside surface down, put the
sheet of Lexan on top, and put it in an oven. When the temperature hit 420F
(if I remember correctly) the Lexan softened and conformed to the inside of
the glass. We trimmed the Lexan to size, reassembled the Lexan and glass to
the front of the CRT, and glued the steel mounting band in place. It looks
great, and is probably a lot safer than just leaving the PVA out.

-- 
Michael Thompson