General > General Technical Chat
How dangerous or lethal is HV in CRT devices?
jonovid:
trivia 4 u
I would play with old valve TV chassis as a kid, would get blue corona discharge off the CRT HT make pinwheel spin.
I can not say how much ozone I generatord. but never got zapped because i'm still here ;D
its unknown the level of x rays coming off the output valve .
but many power valves of that time did emit x rays from the gaps in the sides of the plates.
to make a corona discharge generator from an old TV one had to strip the TV cases of all non non essential electronics.
cut out all un-used electronics from the chassis
however this made the HT power supply voltage rise as valve TV cases did not have HT voltage regulation but relied on load & a resistor network.
did blow up a 300v electrolytic capacitor by hooking it up by mistake to 400v coming off the rectifier valve.
-discharge of smoke & spraying electrolyte across the room. :palm:
Jester:
Back in the 70’s in high school electronics class we had a term where we fixed TV’s instead of conventional lab work. The brightest kid in the class was super skinny and was nicknamed Chucky because he was the opposite of Charles Atlas. The bully antagonist was Horowitz, big and as stupid as they come would have married his sister if given the choice. Horowitz made it his mission to give Chucky a hard time. It started with Horowitz charging up a 100V capacitor, sneaking up behind Chucky while he was probing inside a TV and then touching the capacitor to Chucky to give him a jolt. This went on and on with ever larger capacitors and escalating voltage levels. One day Horowitz showed us this huge string of series capacitors that he was planning to use on Chucky, Horowitz then proceeded to charge up the contraption with the 25kV anode connection on one of the TV’s. We heard a good snap and Horowitz came flying out of the back side of the TV and crashed into everything in his way. We all had a good laugh and that was the last time Horowitz attempted to shock Chucky.
floobydust:
CRT HV was mainly scary and risky when you had to go in the set to probe things. You can't always access the underside of a pcb or chassis to scope things.
Putting your arm inside the chassis, the electrostatic crackling and your arm/hand hair getting pulled up is scary, not for the faint-hearted. Because your arm's reflexes can jerk and you don't want to hit the CRT neck, it's like a Zen experience. Measuring the CRT HV with a HV probe was not nearly as scary as putting your arm in there. I still glow from 6BK4 radiation...
In the shop one tech would charge electrolytic capacitors to 450VDC and throw them, yelling "catch!". If you caught the cap you got nailed. I never did, just let them land on the ground. The Heathkit cap tester could charge to 600VDC. Probably could kill someone that much DC hand to hand :phew:
tautech:
--- Quote from: floobydust on January 29, 2022, 07:36:59 pm ---In the shop one tech would charge electrolytic capacitors to 450VDC and throw them, yelling "catch!". If you caught the cap you got nailed. I never did, just let them land on the ground. The Heathkit cap tester could charge to 600VDC. Probably could kill someone that much DC hand to hand :phew:
--- End quote ---
Mechanic shops played that game too back when ignitions were all points based. Charge points suppression cap with ignition tester and play catch the ZAP !
New ones that didn't leak much just left charged on a workbench would catch out the unwary too ! >:D
Vtile:
Games for true idiots.
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