At 20:36 19-02-02 -0500, you wrote: > > (For those who don't know, the rule-of-thumb for flyback voltage that I > > learned is 1kV/inch of diagonal measurement, e.g., a 12" CRT would have a > > 12,000-volt flyback voltage. And it's stored in a capacitor, so--as Kevin > > noted--it can get you even when the set is turned off and the power is > > disconnected. Which is the point behind the earlier safety warnings about > > working on such equipment. There _is_ a proper, safe way to discharge the > > flyback voltage capacitor, but it does _not_ involve putting your finger >in > > the hole . . . ) > >27kV! Cool. It never got better. My friend never knew about the CRT voltage.
Perhaps he should have read my manual. ;-) Next to the <bold><very large>WARNING</bold></very large> notice about the voltage, I got one of the graphics guys to draw a picture of a technician with his hand still inside the equipment while the rest of him had been reduced to a skeleton with smoke rising from his bones and clothes . . . (I made a similar warning sign for the ca. 5kV HV power supply used to power gas discharge tubes for spectroscopy experiments in class. A bit extreme, perhaps, but it gets the message across.) >After seeing me get lit up he started discharging the tubes, by sticking a >large screwdriver wrapped with a grounding wire into the hole. FWIW, that _is_ essentially the proper way to discharge the flyback voltage capacitor. Hooking the other end of the ground wire to the proper place (rather than, say, to the fly of your trousers) is also important, of course. I usually used a screwdriver with about a 1/8" wide blade and about an 8" shaft, with a jumper cable with alligator clips with one end clamped onto the shaft of the screwdriver and the other end clamped somewhere on the chassis. >This guy isn't dumb, he just likes sparks. I might observe that from a safety standpoint anybody who likes sparks that much _is_ being dumb. I prefer to _avoid_ sparks as often as I can. (Though admittedly that incident in the nuclear lab I described earlier is not the only time I have _unintentionally_ created some memorable ones.) >He works for himself now fixing medical >equipment for hospitals. I won't say where, don't want to knock down the >tourist trade. > >Kevin T. -- Ronn! :)
