Discharge a crt

[erzane]

When discharging the tube, should I first :
1. disconnect DC, disconnect all wires linked to the chassis (neckboard wire, rotation VL connector, coil, video), then discharge the tube, then extract the sucker?
2. disconeect DC, first discharge the tube (screwdriver trick), extract the sucker, then disconnect all wires linked to the chassis?

Also, when doing the screwdriver trick, should I insert the screwdriver under the sucker deep enough until I touch the metal pin of the hook?

I heard about some recent monitors (since when?) does have an auto discharge, I don't know if mine does (Nanao MS8-18 series chassis/Mistsubishi tube), but usually I always disconnect DC and all wires first, then extract the sucker with gloves. But I never discharged the tube with the screwdriver trick before.
Today, when mounting the chassis back to the tube, after I have reconnected all wires (except DC of course), I was putting the sucker back and an electric thunder appeared, then I felt a little electrocution. Now I'm worrying, so I better have to discharge the THT before with the screwdriver stuff...

Usually I wait 12h before extracting the sucker, then I touch the tube with a screwdriver (I ever thought we shoud do it that way but now I know it's a silly habit) and I never had any problems. Maybe because usually I do this after having disconnected all wires linked to the chassis, but I'm not sure.
But recently I read that 12hours isn't enough, since a tube can keep the 20000V during years.

[nem]

The tube holds the charge. What I do is I push one of the metal hooks under the anode cap with the screwdriver, lift off the cap, then prod the inside of the hole ( ). You'll want to prod it again ( ) when you're connecting the cap back on.

Also, when sliding in the screwdriver, don't slide it across the tube surface, slide it across the top of the cap. Otherwise you're scratching up the HV insulating paint every time you're doing it.

[arttu]

Disconnect DC, put one hand in your back pocket and don't take it out, and then do the screwdriver trick with the other hand by touching the anode under the cap. Do that couple of times, waiting 30 secs or so between discharges. Most monitors have auto discharge but it can fail, so I always assume the monitor does not have auto discharge even if it's supposed to have one.

The reason for me writing this comment is this: some of the big caps in the chassis can contain relatively high charge, so it's sensible to short those too (AFTER doing the screwdriver trick). I must confess that I never do this, so this is a classic case of "don't do as I do, do as I say"

So the order is: disconnect dc > screwdriver trick > disconnect sucker from tube > disconnect chassis > empty big caps in chassis > any other stuff

[erzane]

>Nem: I'll prefere to hook the other side of the wire to the monitors frame instead to the anode if it's also correct (pls see pic#3).

> Arttu: Seems mine does also have an auto discharge since I never did the screwdriver trick before and it's the first time I have an electrocution. So, if I understand what you want to say, I also will have to touch (''short'') the sucker cap (relatively to my last pic) since the flyback (TNT) of ''the chassis can contain relatively high charge''? Btw, do you mean by ''short big caps in chassis'': touching the pin of the cap with the screwdriver trick right?

If I understood well, here are the steps to put the sucker cap back (after have seen small and short thunderlights and got a little electrocution when trying to put that sucker back yesterday). This should serve not only me but every old or new members there since I didn't see a precise topic relative to that subject before unless google. I just hope my pics and precision would be usefull:

[arttu]

What I meant (sorry if this is too simple but I want to be as clear as possible) - was:

1. when you put the screwdriver (other side mounted to the chassis with a FAT wire, a normal thin wire will not do - use a thin enough wire and it'll start burning) under the anode cap "sucker" before removing the anode cap and do that couple of times, that's the only time you have to do anything "electrical" with the cap "sucker". When you put it back, you don't have to do anything. Always make it the first step to do the screwdriver trick when you are doing something with the monitor: even if you are doing something completely other thing than removing the anode cap "sucker" (checking solder joints etc), always do the screwdriver trick anyway. For example the neck board can contain high voltages. Always do the screwdriver trick. With one hand, and other hand in your back pocket.

2. the meaning of "the chassis can contain relatively high charge" is that REGARDLESS of doing the screwdriver trick or not (which you do always anyway so "not doing it" is purely theoretical), the big capacitors on the monitor PCB(s) can contain a high charge. To empty the charge in the large capacitors:
- DO NOT touch the capacitor legs with the screwdriver
- DO NOT connect the capacitors legs together with a wire
- what you can do is to have a wire with a, say, wire with a light bulb - touch the capacitor's both legs and when the light bulb is dimmed, you know there is not a lot of voltage stored in the capacitors anymore. Or better yet, don't trust what I'm saying, check for more professional info here: https://www.repairfaq.org/sam/captest.htm#ctdtk


The steps to put the sucker cap back in is just to squeeze it and put it in place. Nothing else. You discharge it before you remove it. You discharge it while it's in place, connected to the monitor "glass". When putting it back, every component is just a piece of metal without any charge, completely safe (except for dielectric absorption, google it).

If some step is not clear, for your own safety, don't do it. If everything is perfectly clear, don't do it alone - do it when you have another person within a shouting distance. Sorry if I sound patronising, but a broken monitor is better than broken you

[erzane]

Thanks for your precisions. Your explanations are clear to me

Btw, when you says: ''when putting it back, every component is just a piece of metal without any charge, completely safe [...] except for dielectric absorption''.
I'd like to find out why I've seen a small thunderlight inside the hole and get lightly electrocuted yesterday (maybe ''dielectric absorption'').
In fact, yesterday I putted the sucker back with every wires reconnected to the chassis (except DC of course), but usually I put the sucker back all the wires disconnected. So maybe this time the flyback gave voltage to the sucker, and when I putted it inside the hole that charge get alive/transmitted.

Also, when taking the sucker off: using a 18awg is ok? More, another guy told me that it's dangerous to use a so small screwdriverr like mine, his advise is to use a very big one, with aligator hook, what's your opinion on this (pls see pic).
p.s. btw, it's been two years now I handle that monitor and take the sucker off only by touching any metal part on the tube with my gloves and a tiny screwdriver, without any wire nor aligator hooked to it or to the frame and I never had any problems.