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Author Topic: CRT - Pop When Discharging  (Read 329 times)

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morton

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CRT - Pop When Discharging
« on: May 19, 2017, 09:27:27 am »
I am attempting to take a TV out of its casing for a cabinet build, and am just wanting to inquire about the "pop" sound when discharging a CRT. As I understand it, the metal clip under the cap is shorted on the screw driver and the "pop" happens. When I was discharging mine, a lawnmower was started outside and I could not audibly hear a pop or see any arc (due to cap). I know for certain that the driver touched the metal, and I waited 20 mins, and did it again. No pop.

Now being a careful guy, a few things entered my mind:

- It did not discharge and I am doing it wrong (I have a pretty good understanding of electronics, and this seems unlikely - but can't rule it out)

- The discharge was successful and I did not audibly hear it due to my having to work in the garage like a rat.

- I need a proper workshop space where I can focus on things  :lol

So now I am staring at this TV wondering what the best action would be, as I am in no rush, so asking a million questions seems to be the best thing I can think of ATM. Any advice is appreciated. Thanks.

JDFan

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Re: CRT - Pop When Discharging
« Reply #1 on: May 19, 2017, 10:54:52 am »
How long had the TV been sitting without being plugged in ? -- could also be most of the charge had already dissipated so there was no audible pop  :dunno

harveybirdman

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Re: CRT - Pop When Discharging
« Reply #2 on: May 19, 2017, 11:21:34 am »
Also some newer monitors discharge on power down, I've never heard an audible pop on my WG k7000, I still use the probe though, twice every time just to be sure.

morton

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Re: CRT - Pop When Discharging
« Reply #3 on: May 19, 2017, 01:50:03 pm »
It was plugged in briefly the day before.

lettuce

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Re: CRT - Pop When Discharging
« Reply #4 on: May 21, 2017, 04:46:26 pm »
Ive must have discharged approx 5 or so CRTs over my 10 or so years building cabs and i have never had a discharge pop/crack ever, im guessing as they are fairly modern CRT (1990's) and i think a lot of them auto discharge themselves when you turn them off. So as long as you are certain that the screw driver has made contact with the metal clip on the yoke at least a few times then you should be safe to remove the cap.

That said i have seen some dumb arse people on YouTube remove the yoke cap without discharging and just by yanking it out and taking no care what so ever or other people actually getting the yoke hole to arc on the screw drive shaft. Whilst the voltage in a CRT should be respected and due care taken i think it is a lot safer than most people make out what with the horror stories and what not.

But as i said if you respect it and take the proper precaution and follow the correct way to discharge the CRT (like you have) then you should be total safe and as said most modern-ish CRT will auto discharge themselves which i think yours does as there is no pop/crack sound

yotsuya

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Re: CRT - Pop When Discharging
« Reply #5 on: May 23, 2017, 10:19:58 am »
I've done dozens of discharges and have never heard a pop. You should be fine.


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ChadTower

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Re: CRT - Pop When Discharging
« Reply #6 on: June 01, 2017, 11:11:14 am »



I only occasionally hear a pop.  I think that happens mostly because you haven't quite made the right contact and the discharge arced under the cap.  You year the arc.  I don't hear a pop most of the time.


If you're going to do this even occasionally I'd get a high voltage probe.  It's so much easier than the screwdriver method and much less likely to scratch the coating on the glass around the anode.  Scratch that glass and you can destroy your tube.

behrmr

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Re: CRT - Pop When Discharging
« Reply #7 on: June 01, 2017, 12:12:49 pm »
Most TVs and some arcade monitors have a bleed off circuit so when working there's no or little residual charge in the tube. And as mentioned without an HV probe you can't be sure. But either way you should be fine if you grounded it for a a couple of seconds. And if not you'll get zapped, curse, and love on with your project.

  
 

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