FWIW, the cheapest way to get such a CRT is to buy a cheap portable TV -- even a new one -- and raid the CRT from it. The old method for this is 'tighten until the CRT implodes, then back off quarter of a turn' :-). [Note : If you don't realise this is a joke, then you shouldn't be attempting a CRT replacement, OK!!!] Unless there's a bleeder resistor in the EHT supply -- and AFAIK there isn't in the M4, so there probably isn't in the M12 either -- the CRT can hold a charge for a lot longer than 'overnight'. The charge is not generally enough to be lethal, but it's a nasty shock, and it may cause you to drop the CRT. I alwayse discharge a CRT with my EHT probe before handling it. Don't discharge it by shorting the anode connector to the chassis -- not even to the CRT earth (the spring contact onto the outer aquadag coating). The resulting spike can take out chips all over the machine. You have been warned! -tony

They do. But how fast "naturally" is depends on a lot of factors, everything from how dirty the tube's outer surface is to what the atmosphere is like. Some of these things you can't do much about. But some you can - for example, if you keep it in a humid environment, it will discharge faster. (Whether it will be fast enough for "overnight" to be safe, I don't know - my idea of "high voltage" generally starts somewhere around thirty or forty volts.) /~\ The ASCII der Mouse \ / Ribbon Campaign X Against HTML mouse(a)rodents.montreal.qc.ca / \ Email! 7D C8 61 52 5D E7 2D 39 4E F1 31 3E E8 B3 27 4B

THAT I'd like to see. Cheers -- Adrian/Witchy Owner & Webmaster, Binary Dinosaurs www.binarydinosaurs.co.uk - possibly the UK's biggest online computer museum www.snakebiteandblack.co.uk - ex-monthly gothic shenanigans :o(

Actually that depends....... If the tube is PERFECTLY clean, and the water is distilled, and NO contaminants have entered from any source then the answer is a resounding NO! Of course it is practically impossible to achieve these conditions..... I (when MUCH younger) did a simple test. Put two electrodes into a container of distilled water. Measure the current flow..... Under the best of cirsumstances I was able to get about 3 minutes of negligable current flow. Then it would rise rapidly until if popped a breaker, blew a fuse, generated smoke (burning wires), or exploded ( Do NOT drop a pinch of salt into the water while running this experiment.......) If fact if you are at all sane, do not attempt this experiment at all!!!!!!!!

Haven't you just described a kettle? :) w

heh heh!! us? sane? ----- Original Message ----- From: "David V. Corbin" <dvcorbin(a)optonline.net> To: "'General Discussion: On-Topic and Off-Topic Posts'" <cctalk(a)classiccmp.org> Sent: Thursday, March 04, 2004 5:26 PM Subject: RE: TRS-80 Model 12 crt substitution container NOT

I can confirm that glass is very good insulator too. Mere dirt even greasy smear even a incomplete air-seal (HV cup) is enough for HV to escape with a (SNAP!, crackling or hissssing). Even a tight pinhole in rubber/silicon/plastic insulations that can hold back water didn't stop HV's dramatic exit. That one I had one, had to find it with HV probe waving around each HV cup (three in a set for projector and that particular set has secondary HV hat loosely placed over each HV cup and kept in place by wedge force) till I see some deflection it apart and finally found the burn spot on the metal HV clip that matched a microsopic pinhole in the rubber cup. Oh, as other have said about the "power" of the HV it is very powerful enough to "eat" through if insulations has flaws in it. I see this often in flyback transformers & botched HV splitter installions. One time I seen "tufts" of impossibly fine magnet wires for HV stuck out of crack encircling flyback's round body where flyback transformer housing split open with a BANG according to owner whom heard the noise. For this reason, manufacture of HV stuff had to be super clean and quality stuff, HV resistors, caps, diodes, very carefully manufacturing steps, vacuum vessel to "boil" potted units prior to curing. That's the reason for not filling potting stuff to the brim. It's below the rim of housings about 1cm depth. Deduced from my reasonings. 33 to 35KV is "asolute" max for consumer stuff including projectors. Anybody care to raise reason behind this HV "wall"? Not just for x-ray reasons. I use is I think 180 Ohm 20W sandbar resistor for both HV and main filter caps as discharger. Much gentler on stuff and sanity. Cheers, Wizard