Opening up a CRT: dangerous?

[AntiPasta]

Damn, I'm out of my parents house for one week and when I get back the power button on my computer's screen has been pushed in too far and now it won't spring back... which oddly renders the OSD inoperable. So, I set forth to open up the screen, first removing the plastic housing. However, upon seeing the coils, fat capacitors and super-insulated cables I felt a hint of The Fear creeping up my spine... is there any danger of electrocution? Before I can get at the power button, I'm gonna have to remove the front part of the plastic housing, that sits around the front of the tube (the one I removed goes from the back to about 5 cm from the front, but there's all sort of weird cabling going around the front of the tube. What I do?

[the_steadster]

Just discharge the caps, from what ive heard thats the only danger. Of course, i could be talking shite - A quick external bodge could be a better option

[Zilog Jones]

CRTs are the only thing I'm scared of taking apart. I've already got electrocuted by 127V... twice... when I was about 7 - God knows what 20kV will feel like!

Isn't there something about the tube holding a charge as well as the cap's? If you leave it unplugged for about a month (or is it more?) you'll *probably* be OK, but I dunno if you want to wait that long.

[Divine Evolution]

They do make a special tool to draw off all that stored power, if you don't have that tool DON'T do ANYTHING with it, it is LETHAL!
Also note: NEVER use a grounding strap with a CRT, it gives the electricity a straight path to you.
~Krelian

[Taemos]

If I ever have a problem with a monitor, I throw it out and buy a new one. You couldn't pay me to open one up.

[Yakumo]

NEVER mess with a CRT !! I touched the back of the tube once and let me tell you that I'm bloody lucky to be here ! I'd never felt such a feeling in all my life. My hand was shot back by the force and I could feel my heart beat speed up to quite a fast pace. Everything sort of when blackish too. was I on my way to death's door? Who knows but I do know one thing, I'm never touching the back of a CRT again without wearing a pair of rubber gloves.

I read that even if the monitor/TV has been off for an hour it still retains it's electrical charge.

Yakumo

[Zilog Jones]

It'll still keep a charge for quite a while - days more than hours. That's why I said to leave it about a month just be on the safe side. Though I can't remember if even that's long enough...

Let's just be thankful that modern TV tubes are very unlikely to IMPLODE, unlike ones from the 60's and before...

[Topic Archive]

Let's just be thankful that modern TV tubes are very unlikely to IMPLODE, unlike ones from the 60's and before...


This is not true, ALL CRT's are vacuum sealed, be that old or new...

...But they only implode when they break ;)

[Calpis]

It's very awesome to watch a CRT implode ;) Sparks swirl around

[the_steadster]

Just discharge the caps, from what ive heard thats the only danger.


From all the later replies, I'd ignore my advice - Unless you have a deathwish that is

[madhatter256]

If its all for the plastic button to turn it on, simply hit the area around the button to knock it back up into place.

[LeGIt]

hehe it wouldnt actually be a problem for me as I've got 4 other CRT's of decent quality I picked up dirt cheap :D

But a few years back I did have 1 where after my mate did something the power was always on, so I just sold it for £10 and dug up a spare xD

[Blur2040]

I'd say only touch it if you're feeling bold, and find good directions on how to properly discharge a CRT.

[Dragyth]

I've opened mine before, nothing to worry about there.
Just don't touch anything inside =)
I managed to seperate the whole case from it, though, to fix my power button.... that isn't fixed.
Lovely monitor, though.
Sony 17" CRT, completely flat, fantastic colour and incredible clarity, a real gem =)
It operates at 85HZ 1280x1024, you can run it in 1600x1200, though.

[Zilog Jones]

This is not true, ALL CRT's are vacuum sealed, be that old or new...

...But they only implode when they break ;)

Yeah, but there's loads of regulations and precautions and stuff these days to stop this from happening. The screens are pretty well protected - I remember seeing some kids hitting a CRT screen with a hammer once, and it was pretty much just bouncing off! But it wasn't always like this...

[Calpis]

Those were some really smart kids lol

[MD]

The front of a tube is quite strong and will probably not break if you hit it with a hammer, sadly do that with the neck and that is another thing. Some tubes will implode then explode if you manage to break the neck so be warned.

Basically if it's switched off then you probably won't have too much to worry about, the caps won't be exposed from the top and nearly all modern monitors and TVs discharge the stored charge from the tube. At worst the caps would give you a nasty kick but they won't kill you as most are under 50 volts... The tube probably won't kill you, just hurt a lot. Just don't go anywhere the anode (rubber thing at top of the TV) or the neck of the tube.

If you think you can get to the switch then you could wear rubber soled shoes, a jacket that covers your arms and some rubber gloves and push that button out or seek professional help (what help is up to you...). :D

Failing that look up Discharing Tubes or Discharing Monitors on the next, thenit'll be safe to work with completely.

[ASSEMbler]

crt = death

Don't do it unless you are a technician

I'm a pc tech and saw someone in class die doing this.

[WolverineDK]

crt = death

Don't do it unless you are a technician

I'm a pc tech and saw someone in class die doing this.
shit :-/

[Yakumo]

Like ASSEMbler said, Don't mess about with a CRT. As I posted above it can be very nasty. I honestly thought I was going to die when I was hit by a shit load of electricity. I'm not too sure what part it came from but I'm 90% it was the back of the tube (neck area).

Yakumo

[Alchy]

You're lucky to be alive.

CRTs are the only thing I'm scared of taking apart.Amen to that.

[Paulo]

Your mad anti...

[AntiPasta]

I think I'm lucky to be alive then, some years ago me & my brother were tinkering with a 22" Supermac workstation screen, we had the plastic casing off while it was running (trying to figure out a way to connect it with its weird 13w3 connector) - though it did have huge metal sheets around it.

Problem solved though, my brother decided to buy the CRT even though the button is dodgy. End loss: 0 euros :D

[GaijinPunch]

As I posted above it can be very nasty. I honestly thought I was going to die when I was hit by a shit load of electricity.

How many times in your life have you heard, "that would explain a lot" b/c of your incident?

[tekaotaku]

have to agree with everything being said, a few years ago I was messing about with an old 14" TV, it just died one day and me being the clever sod I think I am I went ahead and stripped the plastic off.

Took an electricians screwdriver and poped it under a sealed rubber hose attached to the neck of the CRT, needless to say my hand and arm was shot away from the tube, the screen "popped" and I was left crying on the floor breathless for a good 10mins clutching my arm and waiting for my heart to stop beating like a bastard.

So in short, CRT + Cock sure attitude = sticky horrible burning fleshy tingling sensation.

to quote zammo, just say no.

[Taemos]

I saved someone's ass then. My friend's brother wanted to fix their TV.

I told the guy to stay the fuck away from it :). Trash it and get a new one.

[Wozza]

Anything that involves opening one of these up - take it to a proffesional or flog it. Getting it fixed is very pricey but better than killing yourself. I have also heard a lot of stories about people trying to mess with CRT's.

[AntiPasta]

Took an electricians screwdriver and poped it under a sealed rubber hose attached to the neck of the CRT,

Well that in particular is the nasty part, that's why it's insulated so well...

[Alchy]

Just a quick note while I remember, along the same lines - don't put potted plants on top of your TVs and then water them for several months, either. My mum did this at one stage and ended up filling a few inches of water in the bottom of the TV, at which point, predictably, it stopped working. The engineer who came to look at it had a fit, but it worked fine once emptied and I got it as a spare... cheers mum...

[socialdrone]

i think i remeber you need a crt tool with a 10 Megohm (maybe larger) resistor...
crts can store a lethal charge for years not just days, so id allways be very carefull.

plus the crt isnt the only thing you need to watch out for, there could be a number of capacitors that could do some damage to you.


do not use a screwdriver and a piece of wire... unless you have a friend standing by with an automatic defibulator.

[OldProgie]

The tube itself acts as a huge capacitor, very similar to the first capacitors known as Dewar Jars.

Due to the high insulation properties of the glass tube, these charges can remain for a very long time.

If you touch the contacts at the back of the tube, the only resistance in the circuit is you. Using the formulas V=IR and Q=I^2R (I'll let someone else work out the maths) you can work out that there's a lot of energy there which WILL kill.

[macwest]

If you never have worked on one and have not had electrical training stay clear. I have worked with electronics for years and not knowing what you are doing can kill you or at least paralize you for life. Problem with electricity is it offsets your heart pattern so even if you are shocked today the results may not show up till later.

[GaijinPunch]

Problem with electricity is it offsets your heart pattern so even if you are shocked today the results may not show up till later.

I'd say instantaneous death is another problem. ;)

[macwest]

I'd say instantaneous death is another problem. ;)


just a small one.

[Taemos]

I'd actually rather have it over and done with if the heart problem isn't fixable :).

[MD]

do not use a screwdriver and a piece of wire... unless you have a friend standing by with an automatic defibulator.

Funny, that's how I've been discharging tubes for the last ten years. Then again I've seen people discharge monitors with two screwdrivers, a Multimeter lead and a crocodile clip and even just wire.

I know someone that has had tube shocks at least 10 times, he says it feels like someone hit your elbow with a sledgehammer (he has also said it felt like a static electric shock too) but he is still walking around. Unless you have a heart condition then a tube shock probably won't kill you, but you'll probably wish it had. :P

The vast majority of deaths from monitors are caused by shocks when there is electricity going through them (ie plugged in and switched on) as then you are dealing with around 20KV at a fairly reasonable current.

High voltage won't kill you, current kills you. If you've ever had a static shock then that is effectively 10,000V discharging via your body... I've had a 200V 2000Uf Cap (generally the largest cap on a board, ignoring the mylar 2KV 1000pf caps which don't hold charge) shock and it felt like a static shock. I only got this shock by removing the main board from a chassis and dropping the board and touching said cap when trying to catch it.

[AntiPasta]

The tube itself acts as a huge capacitor, very similar to the first capacitors known as Dewar Jars.


Dewar Jars? I think that's what we use for temporary storage of liquid nitrogen (well, we call em 'dewars' but they resemble a jar)

[Yakumo]

I get bad static electricity shocks here in Japan. Some are so bad that I see the blue spark. THey really hurt but won't kill me. I now walk around with a discharger when ever I drive or go the arcades. It's just a small metal tube with a LED inside. If I touch a metalic item with this the LED lights up with the electricity from my body. After that it's safe to toch anything fora while :p I remember once in Sega World I went to put my 100 yen in to the slot of a machine when I suddenly received a very nasty shock. I ended up throwing the 100 yen in to the air where it landed on some guys head next to me :D He wasn't impressed at all.

Yakumo

[WolverineDK]

I get bad static electricity shocks here in Japan. Some are so bad that I see the blue spark. THey really hurt but won't kill me. I now walk around with a discharger when ever I drive or go the arcades. It's just a small metal tube with a LED inside. If I touch a metalic item with this the LED lights up with the electricity from my body. After that it's safe to toch anything fora while :p I remember once in Sega World I went to put my 100 yen in to the slot of a machine when I suddenly received a very nasty shock. I ended up throwing the 100 yen in to the air where it landed on some guys head next to me :D He wasn't impressed at all.

Yakumo


i think you bowed your head and said Surrimasen and told why you got shocked.

[Zilog Jones]

It's "sumimasen". You should play Shenmue 2 more ;)

And yeah, Japan must suck for that kind of stuff - mains sockets don't even have earth pins, FFS!

[Yakumo]

For Fucks Sake is right ! Actually some "Special" scokets do have earths. My PC is connected to one as is the Air Conditioner and Fridge. The thing is that you don't even have to use the earth for these items to work. I think the japanese plugs are nasty.

Yakumo

[AntiPasta]

lol, the words "japanese", "air conditioner" and "fridge" bring up memories - back in the Gaijin House, were everything was decrepit and rusty, the PC, AC, fridge and microwave were all hooked up to the same socket.... so if somebody turned the microwave on while the AC was on already, and somebody else was using the PC, power would cut out... which made for some pretty funny occurrences :P