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0 pointsuserbinator7mo ago0 comments

The main danger with CRT HV is not the HV itself but what the shock will make you do, such as jump and cut your hand on something sharp in the chassis, or even crack the neck of the tube, or fall and hit yourself. There is very little current available, especially if the set has been off, but it's comparable to a very painful static shock. Instead, the "low" voltage B+ supply is far more dangerous when the set is on, as that is basically rectified mains.

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analog317mo ago

Beware. I took a poke from the focus anode of a CRT when I had a job repairing mainframe terminals in the early 80s. I thought I had discharged it, but apparently I didn't.

I had to sit down in a quiet room for the rest of the work day, before I could function again. It was probably 13 kV, which was typical for monochrome displays back in the day.

Also, anything in a CRT television can kill you because TV's tended to have a "hot" chassis. The repairmen always plugged a TV into an isolation transformer so they could ground its chassis while working on it. There's a lot of counterintuitive things about those old electronics due to clever cost reductions.

userbinatorOP7mo ago

The focus anode is lower voltage (~1kV) but its supply may be capable of higher current.

analog317mo ago

I might have gotten my terms mixed up, but it's the suction cup thingy on the side of the tube. And it was disconnected, so the poke I got was from the charge built up on the capacitance.

We had a procedure for discharging it, which I must have bungled.

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0 pointsuserbinator7mo ago0 comments

0 comments

analog317mo ago

Beware. I took a poke from the focus anode of a CRT when I had a job repairing mainframe terminals in the early 80s. I thought I had discharged it, but apparently I didn't.

I had to sit down in a quiet room for the rest of the work day, before I could function again. It was probably 13 kV, which was typical for monochrome displays back in the day.

userbinatorOP7mo ago

The focus anode is lower voltage (~1kV) but its supply may be capable of higher current.

analog317mo ago

I might have gotten my terms mixed up, but it's the suction cup thingy on the side of the tube. And it was disconnected, so the poke I got was from the charge built up on the capacitance.

We had a procedure for discharging it, which I must have bungled.

j / k navigate · click thread line to collapse