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From DigiBarn virtual visitor Dirk Niggemann on those mystery spots: I assume you do know what the spots on the 3101 VDU _really_ are and that you are merely teasing the audience... This not being a reliable thing to assume I will mention the fact that it appears a lot of terminals from the 70s to the early 80s, especially those that survived many years of 'garage' storage in a damp environment suffer from two problems: a) delamination of safety glass screen from CRT envelope. I assume the adhesive used was some sort of thermoset polyester or amide type compound which is both hygroscopic and biodegradable. This is very annoying as nearly unfixable unless you enjoy the prospect of wearing full protective gear (kevlar bib and gloves and 360 faceshield minimum) while trying to pull/steam/heatgun the safety glass off the tube, leaving something you should be able to crack with a light tap from a 1/4 pound hammer. Alternatively, you could try acquiring a high vacuum pump (You'll need to enjoy mercury vapour poisoning in your spare time) and some (zirconium?) getter and try actually 'letting down' the tube before you attempt to remove the faceplate. Recommend you try that one with too much spare time and a couple of newer green-screens you really don't care about first. You might want to practice lab glass-blowing first, too. And look up some old patents on pinch-sealing vacuum tubes as well. b) accumulation of mildew/mold in the bonding layer between the CRT and the safety glass front, after a). Unless the mildew is actually beneath a glare screen you will face the same problems as in a). This one even looks like it has a combined case of algae and mildew. Unless (silly theoretical hat on here) you can extract the CRT, coat any exposed metal surfaces with something moisture-repellant, and stick the whole thing in a steamy atmosphere at about 110F until the mildew decides it's eaten all the glue it can. It which point the whole thing might come apart, with about the same level of extreme personal danger as suggested above. Unless of course the faceplate is fused on....at which point you get out the diamond edged glass-cutters and stand _well_ back. Well if really brave you could stick the whole thing in a concentrated NaOH bath in the hope it dissolves the adhesive... In any case, you may have a very fun time fixing this. Rather suggest
you attempt to acquire a CRT of equal spec and vintage and swap it out.
I think the green models (can't remember phosphor description) with mag
deflection were quite standardized by the time, provided it's a Japanese
one.
The Cromemco C-10 and Cromemco parts See Cromemco donor Michael Bett's bio here. |
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