Van: Mattis Lind via cctalk<mailto:cctalk@classiccmp.org> Verzonden: vrijdag 17 november 2017 11:52 Aan: David Collins<mailto:davidkcolli...@gmail.com>; General Discussion: On-Topic and Off-Topic Posts<mailto:cctalk@classiccmp.org> Onderwerp: Re: Playing with HP2640B
The screen on my HP2640 had degenerated quite far. It was only a spot in the middle, 2 by 4 inch, that still attached the glass to the CRT. I used a thin fish fillet knife to dig through the remaining glue. Before https://scontent-arn2-1.xx.fbcdn.net/v/t1.0-9/23622163_10155696765784985_6518064439030378363_n.jpg?oh=44cbf7f7f00d6e25155c208124e20a38&oe=5AA7349D The result after: https://scontent-arn2-1.xx.fbcdn.net/v/t1.0-9/23621971_10155696757184985_1959733265676657917_n.jpg?oh=36a20689c0fb5a16de7fc4df138a40e0&oe=5A9993B1 Anyhow, I researched the glue a bit. The glue is, as far as I understand, PVAc (PolyVinylAcetate, sometimes also known as PVA). PVAc is not soluble in water. It takes quite high temperature to melt it. However PVAc is soluble in many esters. I bought some Butylacetate. It dissolves sample bits of glue from HP2640 quite well and rapidly. Butylacetate has quite high boiling temperature (about 120 degrees centigrade) and thus does not evaporate that quickly. So my idea is now to test on a 2645 screen or VR201 screen by adding some butylacetate and seal with some thin plastic wrap foil and let it dissolve a bit. Then use the fish fillet knife again and repeat the process. /Mattis Wow! Excellent job Mattis <thumb up> I have seen that HP2640 when it still was in bad shape. The HP2640, that I have, has many tiny spots on the screen. Your “result after” really looks fantastic. What’s not clear to me, after removing the old “protection” sheet, did you apply some new “protection” sheet, or leave the tube “as-is” ? I doubt whether that “protection” sheet would really help much if the tube would implode (for whatever miraculous reason) … Henk
