Did you know that an old TV set can wreck a whole village's broadband?
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The CRT uses very high voltage, up to 30,000 volts or more, but low current. It is seldom fatal. I've been bitten by it many times while working on TVs in my father's repair shop or in customers' homes. The worst injuries were from jabbing my hand into sharp objects when I jumped from the charge. I had a few deep gouges over the years. I remember once when we had a color TV on the bench, with the CRT still in the cabinet, trying to troubleshoot the problem while the TV owner was in the way while watching us. He was a pain, and we were consequently in no hurry. He happened to see the loose high voltage lead, and pointed to it while asking "What is that?" A spark flew about 8 inches from it to his finger, and he found out what it was. He left the shop and came back later to pick up the repaired set.
I feel it is the reaction to the discharge that is a factor that will cause a problem physically. You still need caution when using any activity with an older TV that uses a CRT. Caution should be your best way to work with older equipment.
I remember a problem with a neighbor who thought that to repair a TV was a simple repair. He did not know anything about electronics and should not have opened the back of the TV but he did to only get a big cut in his face because he did not use proper practices when he reached into the cabinet. The discharge for the capacitor is not something one should forget to do since any reaction will be something you will remember for a long time. Maybe not be fatal but it will hurt like hell.
Any cap discharge can cause one to react in away that one will remember for a long time.
Hope this helps so you do not get hurt!
CRT's also have an implosion hazard along with toxic materials.
The CRT's in the US I think had to be limited to 10K volts to limit the x-ray sometime in the 60's.
CRT's also have an implosion hazard along with toxic materials.
The CRT's in the US I think had to be limited to 10K volts to limit the x-ray sometime in the 60's.
I'm surprised - 10KV wouldn't be enough. The idea might have been thrown around. They were using 90º tubes in the '60s. In the '70s they had moved on to 110º tubes, and that got the EHT down to 21KV or so. By contrast, B&W portables had 14KV, and Oscilloscope tubes were 3-4KV.
The favourite 'capacitor' death trap came when changing a tube. There was an EHT lead with a big insulating cap that plugged into the 'screen' part behind the viewing surface. People used to pull the EHT lead, and forget to ground the capacitor. Then they would take the tube out, and carry it off, 4 fingers underneath, and one thumb would end up near the spot for the EHT lead. The spark could jump 25mm (1") to your thumb, whereupon you would drop the tube as you were zapped. The tube would implode at your feet … It had all the makings of a good accident.
The once it happened to me, I didn't actually drop the tube I was pretty impervious to shocks.
There was a big news article on x-rays and the companies were limited by law on voltage. Yes, some of the bigger ones and maybe color were really sending out high doses.
I tried to get rid of my old crt monitors at Bestbuy and they had stopped taking them. I tried a metal recycler but they stopped taking them. I had to drive 60 miles to Austin/Travis county hazardous drop off and argue with the idiots that I really did live in the county.
Anwyays.
"What can be done? Quite a bit, and most of it has already been done. The major X-ray producer in TV is the high-voltage section. When a high-voltage vacuum tube is subjected to 20,000 volts or more, it becomes an X-ray source.
And should the voltage in the set jump from say, 25,000 volts, to 30,000 volts, X-ray output may jump 10 to 20 times.
To date, the biggest culprit in color sets has been the shunt regulator tube. But new circuits and tube designs have just about eliminated this problem. The high-voltage rectifier is another potential trouble spot. One solution is to replace the vacuum-tube rectifier with a solid-state rectifier that cannot produce radiation at any voltage level. Another alternative is proper shielding.
Another possible solution is color picture tubes, like the Sony Trinitron, that do not require the high-voltage levels that produce radiation"
That's stuff going back before my time. I don't think Colour TVs were imported in any numbers before the 1970s. The oldest model I remember was Telefunken & Philips, which each did colour tvs needing a forklift to move them. I got retrained into TVs in 1977. There were refinements all through the 1970s, and 1980s which eliminated nearly all of the issues.
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