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>This is not too hard for someone comfortable with a soldering iron, someone who isn’t scared of drilling a hole in their TV.

And who is comfortable working with EHT. Let's not forget that.

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Event Horizon Telescope?

Extra High Tension

From about ~10 kV in a B&W TV, up to 30 kV in a color TV.

Non-neglectable amperage, therefore this is really dangerous stuff. Never tweak it when it is plugged in.

Actually the high voltage anode lead is very well insulated; if it isn't any more, you'll be sure to notice it quickly (smell, arcing noises and lights, TV stops working eventually). However, in a typical CRT drive circuit you still may find somewhat high-power 100-200 V DC supplies (for deflection drivers and also what powers the LOPT) and low power ~1-3 kV supplies for focus control and such.

Doesn't the (big) capacitors inside stay charged for a couple of hours after the TV being disconnected?

A decent TV/CRT monitor should have high-value bleed resistors to discharge the capacitors, but since high-voltage resistors cost money they probably stopped fitting them about the same time as TV's stopped coming with circuit diagrams.

Even if they are installed you can't know if the resister has failed open until you try it. Always assume the tube is energized until you've grounded it.

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