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  #16  
Old 01-22-2016, 10:49 PM
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old_tv_nut old_tv_nut is offline
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Does anyone here know of a case of someone working on electronics repair getting electrocuted? I can't recall ever hearing of one, but of course that doesn't mean it doesn't happen.

TV trucks with antenna booms, on the other hand, have killed operators, and the incidence does not seem to have been reduced over the years. When we sent out our TV reception test truck, I made sure all personnel, whatever their role in the operation, read and signed a list of safety practices. Some of the most important:

1) No one may raise the mast unassisted. There must be at least one more person spotting power lines and obstructions.
2) If thunder is heard or lightning is seen, the mast may not be raised until at least 30 minutes after activity has stopped.
3) Anyone on the crew who feels the operation is potentially unsafe can force a stop and cannot be over-ridden by anyone else of any level of authority.
We would much rather lose data than people.
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  #17  
Old 01-23-2016, 01:59 AM
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Quote:
Originally Posted by Telecolor 3007 View Post
You can find Beryllium oxide in home use tranzistor radios or that used only in big power stuff?
AFAIK it's only used in high power RF transistors and tubes. Unless you're a radio amateur the only device in that class you might find in a home is the magnetron in a microwave oven. I don't think that these contain beryllium oxide. There will be a very clear warning label on the device if it does.

I've had the odd nasty shock from electronics kit but only one that might have been lethal. I was troubleshooting a 'scope and measuring the EHT on the CRT cathode. About -1.2kV DC. The insulation of the probe wasn't good enough and I got a belt. It hurt. A lot. Mainly due to violent muscle contraction, my arm ached for a couple of days. Fortunately I was also thrown clear by the muscle spasm. That EHT was derived from a mains transformer so there would have been plenty of current available to kill me.

By contrast when 25kV EHT from a Barco monitor jumped out and bit me it was like a bad insect sting. More current available than on a domestic TV but still nowhere near enough to be dangerous. The only real hazard was mechanical. I might have jumped back and hit my head on something.
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Last edited by ppppenguin; 01-23-2016 at 02:05 AM.
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  #18  
Old 01-23-2016, 02:47 PM
dieseljeep dieseljeep is offline
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Quote:
Originally Posted by ppppenguin View Post
AFAIK it's only used in high power RF transistors and tubes. Unless you're a radio amateur the only device in that class you might find in a home is the magnetron in a microwave oven. I don't think that these contain beryllium oxide. There will be a very clear warning label on the device if it does.

I've had the odd nasty shock from electronics kit but only one that might have been lethal. I was troubleshooting a 'scope and measuring the EHT on the CRT cathode. About -1.2kV DC. The insulation of the probe wasn't good enough and I got a belt. It hurt. A lot. Mainly due to violent muscle contraction, my arm ached for a couple of days. Fortunately I was also thrown clear by the muscle spasm. That EHT was derived from a mains transformer so there would have been plenty of current available to kill me.

By contrast when 25kV EHT from a Barco monitor jumped out and bit me it was like a bad insect sting. More current available than on a domestic TV but still nowhere near enough to be dangerous. The only real hazard was mechanical. I might have jumped back and hit my head on something.
RCA referred to their post war design TV's as having a "reduced hazard" high voltage supply, which is a low current HV source, using a flyback instead of a high voltage mains transformer.
The main item, that I have a lot of respect for is the power supply in a microwave oven. The transformer in those puts out over 1000 volts at around an amp. Enough to be fatal.
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