Discharging the tube

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    • Discharging the tube

      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.
    • erzane wrote:

      Can I use a crossed small screwdriver or should I use a big flat one?
      Also, should I do this before disconnecting all wires or can I do it after (maybe a stupid question but I'd like to be clear on this)?


      NO NO NO!

      You want a big metal flat head like this. You also want to make sure you have a good size gauge wire, and alligator clip. I always discharge the flyback before doing anything with the montior, but you can safely disconnect the other wires first. Just be careful around the flyback.

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    • I see, so you have a very big screwdriver. Is it only the head or the whole size of the screwdriver which is important?
      Also, how to discharge the flyback?
      Before your precisions, I was planning to do the following (but seems my scredriver is too small...), so here are the steps I was planning to do to put the sucker cap back:




    • erzane wrote:

      I see, so you have a very big screwdriver. Is it only the head or the whole size of the screwdriver which is important?
      Also, how to discharge the flyback?
      Before your precisions, I was planning to do the following (but seems my scredriver is too small...), so here are the steps I was planning to do to put the sucker cap back:







      Honestly man..... I have no words.

      Why would you use that little ass screwdriver after I just told you not too? You're lucky you didn't kill yourself.

      Its easier to get under the anode cup with a flat head, but the shape of the head ultimately doesnt matter.

      You shouldnt need to stick the screwdriver deep into the hole of the CRT. Just touching the uncoated metal is enough.
      Want to show your support for the Freeware Taito TypeX2 Multi Project?: Buy Niko a Beer! :thumbsup:
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      The post was edited 1 time, last by Niko ().

    • >Niko: I used the past, it don't mean I don't consider your advise.

      I'd like to know the reason of a so big tool since until today (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 and to the frame), I never had any problem. Maybe my chassis does have an auto discharge process... Anyway that's only recently that I heard about that screwdriver trick (btw, I never had a so big tool at home).

      Also, in my first post, I wrote: ''yesterday, when putting the sucker back, I've seen thunderlights inside the hole and get lightly electrocuted''.
      So, I wanna know why there was still charge inside the hole.

      In fact, I did this 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 (yesterday) the flyback gave voltage to the sucker, and when I putted it inside the hole that charge get alive/transmitted.

      What I heard is: if the monitor is disconnected and the sucker already taken off, there isn't charge inside the tube anymore.
      So I'd like to know - when putting the sucker back:
      1. should I touch the hole of the tube with the screwdriver trick (tool+18 awg or thicker+aligator) anyway?
      2. should I also touch the metal hook of the sucker (what you call ''uncoated metal'') with that screwdriver trick?
      3. should I do nothing since nomore charge inside the tube since sucker is already taken off, all wires disconnected and no dead danger?

      Suverman: Ok

      The post was edited 8 times, last by erzane ().

    • erzane wrote:

      if the monitor is disconnected and the sucker already taken off, there isn't charge inside the tube anymore.

      This is wrong. The CRT has two conductive coatings on the inside and outside of the tube, and together they form, along with the glass, what is essentially a high voltage capacitor. However, glass isn't a perfect dielectric, so when you discharge it, it doesn't actually fully discharge.
    • nem wrote:

      erzane wrote:

      if the monitor is disconnected and the sucker already taken off, there isn't charge inside the tube anymore.
      This is wrong. The CRT has two conductive coatings on the inside and outside of the tube, and together they form, along with the glass, what is essentially a high voltage capacitor. However, glass isn't a perfect dielectric, so when you discharge it, it doesn't actually fully discharge.
      I see, so how should I proceed to put my sucker back now we know there is still charge inside? Should I operate directly on the free sucker metal clip? Do you also use a giant screwdriver?

      The post was edited 5 times, last by erzane ().

    • Ok guys, so I'll do it like this.
      Btw, I had confirmation that a 18'' tube cannot be deadly dangerous, at most a hand flickering as I experimented before, so using a tiny 10'' tool can be enough for now since I already extracted the cap without any damage and I just have to put it back, also my monitor works fine and have no issues. But for next times when extracting the sucker again, I ordered a 20'' tool with croc clips to make things proper as Niko saids.

      For now, to resume: I'll do the following a few times to be sure there is no residual charge:
      1. contact the tiny 10'' tool linked to a 18awg wire hooked to the frames corner bolt to discharge the cap (on my already taken off cap).
      2. also the same by contacting the edge of the hole.


      Both operations with a 18awg wire hooked to the corner bolt (and my hand behind my back as suvermans)

      Thanks for your precious advises and concern, I really appreciate your help!

      The post was edited 4 times, last by erzane ().

    • I’d like to chime in..

      Don’t wear baggy clothes or long sleeves.

      Stay away from your monitor frame while you discharge.

      I used jumper cables but that is risky if they fall off or you bump a contact.

      Peace of mind is not very expensive. I paid $30 for mine. Ebay lineman’s electrical gloves. They come in handy if your doing live yoke adjustments for convergence too.