Here you go; there are some good notes buried on the 9835 page: http://www.hpmuseum.net/display_item.php?hw=150 Best, Sean On Fri, Sep 19, 2014 at 9:56 AM, Sean Caron <scaron at umich.edu> wrote:

On 09/19/2014 01:51 PM, Tony Duell wrote: I've heard it suggested that the protective faceplate be reattached using foam tape around the edges to space it a small distance from the CRT face. While not the original design, it at least affords some protection should the CRT envelope fail. According to a couple of patents, a special epoxy resin was used as a binder, but I'm not entirely certain. Dow TV720 is sometimes cited. --Chuck

On 09/20/2014 03:12 PM, Tony Duell wrote: I'm sure that it's certainly not a shatter guard. However, if you looked at US televisions made before about 1956, you'd see that the plain faceplate CRT had a sheet of plate glass installed in front of it. Some of these got as large as 21", but my family had a 7" 1950 Philco that had that sheet of glass also. --Chuck

On 09/21/2014 01:51 PM, Tony Duell wrote: I think we could be in violent agreement. I was responding to the thought that two sheets of separated glass (i.e. a crt faceplate and the outer guard) would not be shatterproof. Bonded together, yes. No perspex faceplates here, but plain old window glass in the early 1950s. Some later sets used it, but keeping the stuff scratch-free was a problem. --Chuck

A few more points. Every CRT manufacuter that I have seen a databook for says htat you must not attempt to remove the outer faceplate. OK, they wanted to sell new CRTs, and they are covering their backsides if something goes wrong, but... That layer is not there for decoration AFAIK all post-war TV sets in the UK have had some kind of implosion protection. Either a 'direct vision' tube with the double faceplate and tension band or (on older sets) a seprate laminanted glass implosion screen/ Given that many of siad sets were made and sold at a time when safety issuees were not taken so eriously (metal-cased devices with no earth wire were common, etc, I feel that the risks of using an unprotected CRT must be major. Given that it appears the adhesive bwetwene the 2 layers of the CRT faceplate is part of the protection (as in 'laminated glass). I wonder if a CERT showing 'fungus' (for want of a better term) is actually unsafe. The adhesive has decayed, will it hold the layers together if the CRT implodes? -tony

In my misspent youth, my folks lived in a small village that had a town dump for garbage disposal. It was not uncommon to see TVs discarded there, and I not too infrequently stood back as far as I could throw and threw rocks to make the CRTs shatter. (This would have been back in the '70s, most likely the early '70s.) It's likely that some of them had had all the vacuum leak out, but at least some of them hadn't (shiny getter patches are a telltale), and the image some writings I have seen paint of an imploding CRT being much like an antipersonnel grenade loaded with glass shards for shrapnel is, at the very least, not universal. As far as I could tell, none of the resulting shards of glass came anywhere close to moving fast enough to reach me, and I wasn't a strong enough thrower to be all _that_ far away. Not that this should be taken as reason to be careless. I wouldn't've wanted to be within a few feet of one, and it's entirely possible that, while that image I mentioned above is not universal, it's not universally false either. And, as tony pointed out, manufacturers consistently spent money on implosion shields in a significantly less safety-conscious time, so there almost certainly _are_ real risks. As for how common it is, well, I've never had a CRT implode on me in any other setting, but I haven't worked on CRT-using devices enough for that to mean all that much. (I _used_ such devices, in the form of terminals, through most of the '80s, but very rarely opened the cases up enough for implosion to be a significant risk.) /~\ The ASCII Mouse \ / Ribbon Campaign X Against HTML mouse at rodents-montreal.org / \ Email! 7D C8 61 52 5D E7 2D 39 4E F1 31 3E E8 B3 27 4B