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Ursprünglicher Beitrag von: Autoharp Bill ,

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That is an answer that could get someone  killed - yes, killed.  I have been working with CRTs for over 50 years (we used to call them picture tubes).  When a CRT implodes shards of glass can fly over 30 feet.  I have seen it.  Others in the room could be injured as well.  The ultor (second anode) voltage is nothing to sneeze at either.[br]

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And yes, I have gotten shocks from 277 volts (one leg of 480 3-phase to ground) no fewer than three times.  Your first could be your last.  Understand that.  Respect that.  That will leave you sore for a week if it doesn’t kill you.  Virtually every day I work with machines that need lethal voltages to do their jobs properly.  I am not afraid of them but I am always respectful of the injury or death they are capable of.[br]

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But you needn’t be afraid of a CRT monitor  -  or an old school TV set either.  Be respectful of the voltages it carries and the fact that any high voltage item  - even if it is only a few milliamps - can injure you.[br]

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I changed my first picture tube (a 19” black and white) when I was 10 years old (1970) and my first color picture tube (25”) when I was 12 (1972).  [br]

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Working with this safely requires one word - respect!  The #1 safety device is the six inches or so between your ears.  Never forget that.  On an almost daily basis I work with equipment that won’t just give you a shock, but contains lethal power that can easily kill you![br]

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There is one thing you should always remember when working with potentially harmful voltages - and remember people have been fatally electrocuted on as little as 24 volts.  The important thing to remember is that your heart runs on a string of electrical impulses.  If you get an electrical flow across your heart, such as one hand being on a voltage source and the other on ground, this voltage across your heart, which is much stronger and completely wrong for what your heart needs, can make your heart stop and start contracting in the wrong ways.  Death or permanent and irreversible brain damage can occur in minutes.

Most professionals work in a way that they cannot get a hand-to-hand shock.  Keeping one hand in your pocket is a good start.[br]

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As far as discharging a second anode, I have always used a flat blade screwdriver and a jumper wire clip,  Nothing elaborate.  But it is also important to know where to discharge it to.  Usually the chassis, but possibly somewhere else.  There should be a label saying where to discharge it.[br]

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In a glass CRT, there is a coating on the inside and the outside of the glass called aquadag.  The coating on the inside is silvery, the coating on the outside is black.  The black is grounded and the silvery coating is connected to the high voltage button on the inside.  These are both conductive surfaces, the glass between them is a dielectric (insulator) and therefore it forms a capacitor, and this is what holds a charge.[br]

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If you are disposing of the CRT, it is best to let the vacuum escape.  at the small end of the neck, there is an electrical connector.  Unplug this, and in the middle of the pin circle there is a glass tube that appears melted, which is called an exhaust tip.  Break this tip off with a pair of pliers and you will hear the air rushing in.  Once that stops the crt is as safe as any other piece of glassware that size.  But beware - if you didn’t discharge that second anode it can still hold quite a charge!  That probably wont hurt you but it can make you drop the CRT.[br]

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In addition to the high voltage on the side, other elements can have several hundred volts.[br]

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There is no poison gas on the inside of a CRT, just a very high near perfect vacuum.

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I don’t want to scare anybody, but it is best that you know what you’re doing and work carefully.  I wish you all the best of luck!

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