Kinda OT. Don't wanna die. What can I touch? >56k warning<

[sanaka]

The front:

40" Sony Wega. A 250 lb. monster CRT. Nicest picture per sq. in. around.
Tragically, it's toast. Or at least totalled - $600 was a maybe fix.
Not so tragically, it's been replaced with a 50" Sony Pro plasma screen

The back:

As nauseating as it may seem, I just want to yank the boards and desolder parts off of them to use on other projects. Throwing rocks at the CRT should be fun too. But it's scary just being close to this thing. Probably just because it's so huge more than anything. Somehow the inside of a 15" computer monitor just isn't so intimidating. Still, I don't want a bad encounter with anything, like the hokey but spooky suction cup thing. What the heck do those do anyway? Some of the caps are big, so it seems if any of them have remained energized, this could be an issue...

The warning label:

Gee, how many mA are lethal at 30kV ?!?!?

So, how much do I need to know to stay safe hacking on this thing? If it's been unplugged for 24+ hours, can I just stick my hands in &/or cut wires with impunity? Like the fat suction cup wire? If you give me advice and then I never post here again it'll be all your fault that I'm dead. [size=xx-small](yah yah, just totally kidding ok?)[/size]

Peace,
Sanaka

P.S. Say could I use whatever transformer is upping V to 30k to build a Jacob's Ladder?

 

[kevin gilmore]

You want to take a long screwdriver, hook it to a cliplead that is
firmly tied to ground. Then you stick the screwdriver under the
the suction cap and discharge the picture tube. After that scrap away.
Discharging any possible charge left in the caps in the switching
power supply is not a bad idea either.

Dont do this,

Years ago when i worked at Zenith we would take dead picture tubes
up to the 4th floor and drop them on the rocks below the back of
the building next to the railroad tracks. Man did they blow up real good.
I really wish video cameras existed back then...

 

[flecom]

Quote:

Originally Posted by kevin gilmore You want to take a long screwdriver, hook it to a cliplead that is firmly tied to ground. Then you stick the screwdriver under the the suction cap and discharge the picture tube. After that scrap away. Discharging any possible charge left in the caps in the switching power supply is not a bad idea either.

IIRC that can cause the caps to explode... somone correct me if im wrong but you dont want to short 30kV through a screwdriver...

great title by the way lol

 

[00940]

There are plenty of very good reasons justifying why Diyaudio.com forbid its users to discuss anything related to working on a TV. If you're not a tech used to work on TVs, you'd better let this thing alone. Well, unless you feel adventurous

 

[DCameronMauch]

What is the exact model number?
I have all the sony service manuals.

 

[kevin gilmore]

The picture tube is the only high voltage capacitor in this unit.
If you want to add a 100 ohm 10 watt resistor you can certainly do this.
Absolutely standard practice for Xray and other high voltage high
current supplies. Can't find my shorting stick at the moment, when i
do i'll post a picture.

here you go...

http://gilmore.chem.northwestern.edu/discharge.jpg

 

[flecom]

make sure to wear safety googles and clench your arse cheecks really hard

 

[jnewman]

Also physically tie one hand behind your back, or stick it through your belt in the back, or something. If you can only touch electrical components and any contacts that might lead to ground with one hand, it makes it pretty hard to actually kill yourself (which isn't to say you won't get a bad electrical burn - you can get burned by pretty tiny caps if they're fully charged, so don't go putting one hand behind your back and then thinking you don't have to go ahead and discharge everything first. It's just an extra safety precaution.)

 

[Megaptera]

Have someone you're not particularly attached to touch it first, of course.

 

[gerG]

um, did they mention what the problem was? It seems a shame to destroy it if the tube is still good.

btw, do plasma sets still have a 2 year half life? I like the picture quality, but I hate the thought of fadeout. Of course, I watch about one movie every 2 weeks, so I probably needn't worry (mostly because I can never justify the $$$

).

Dang Kevin, I am jealous. I always wanted to try that, just to hear what it sounded like. We had to resort to firearms, and you can't hear the tube implode over a .357.

gerG

 

[kevin gilmore]

Here is another trick you should never ever do to a picture tube.

You mark the exact center of the tube. You stand (or lay down)
about 100 feet away. You fire at the exact center with a 22 rifle.
No bigger than that. If you are good what happens is that the
air rushes in the hole so fast the bell collapses sending the electron
gun assembly thru the front of the tube and rather amazing velocity.
Good fun.

I should note that i watched this a few times, but never really had
the nerve to try this one.

We used to do lots of creative things at lunchtime.

During the end of my stay at zenith i got to watch the guy who
did the high voltage transformers. His cubicle was pretty much
encased in 1 inch plexiglas. Since the transformers were under test
they were not potted rather they were in glass jars filled with mineral
oil. I watched him touch 30kv many times. But nothing ever happened
because the rest of him was nowhere near ground, or anything that
could arc to ground.

 

[Edwood]

Quote:

Originally Posted by kevin gilmore Here is another trick you should never ever do to a picture tube..................I should note that i watched this a few times, but never really had the nerve to try this one.

LOL, that's a pretty fair warning there.

Quote:

During the end of my stay at zenith i got to watch the guy who did the high voltage transformers. His cubicle was pretty much encased in 1 inch plexiglas. Since the transformers were under test they were not potted rather they were in glass jars filled with mineral oil. I watched him touch 30kv many times. But nothing ever happened because the rest of him was nowhere near ground, or anything that could arc to ground.

Wow. I guess if you were a really paranoid DIY'er with some money to spare, a tiny "safe room" can be constructed in one's own home?

-Ed

 

[Born2bwire]

Quote:

Originally Posted by kevin gilmore Here is another trick you should never ever do to a picture tube. You mark the exact center of the tube. You stand (or lay down) about 100 feet away. You fire at the exact center with a 22 rifle. No bigger than that. If you are good what happens is that the air rushes in the hole so fast the bell collapses sending the electron gun assembly thru the front of the tube and rather amazing velocity. Good fun. I should note that i watched this a few times, but never really had the nerve to try this one. We used to do lots of creative things at lunchtime. During the end of my stay at zenith i got to watch the guy who did the high voltage transformers. His cubicle was pretty much encased in 1 inch plexiglas. Since the transformers were under test they were not potted rather they were in glass jars filled with mineral oil. I watched him touch 30kv many times. But nothing ever happened because the rest of him was nowhere near ground, or anything that could arc to ground.

God bless nerds with too much time on their hands.

 

[sanaka]

Thanks so much everyone.

Dr. Gilmore: I don't have a screwdriver I would feel is long enough

, but I have some copper bar, wood dowel, and stuff, so I'll build a discharge stick like in your pic. Is the ground prong slot of a regular outlet, i.e. 12 gauge/~20A house wiring, sufficient for grounding this? Also, I really was going to throw rocks, or slingshot marbles, at the tube (don't own any firearms) - I've found it pretty fun to do this with old ~15" monitors - but now you've got me all scared. If I nail the tube just right could it really throw stuff back at me? That dang tube weighs more than me so I figure the more respect, the healthier...

DCameronMauch: The model# is KV-XBR700H And under Manufactured it says "November 2001 DX-1A" When first plugged in the LED flashes in a pattern of 7. When the power button is pushed, the pattern changes to 4 flashes, it makes the normal "TV turning on" electrical whooshing sound, and the screen will make the hair on your arm prick up, but other than that it acts dead. The only auth. Sony guy around here said this probably indicates a certain board is fried (that's the only troubleshooting they apparently do anymore), and if that's accurate then replacing it would fix it. But that would be $600, and in his opinion these sets are unreliable anyway. So the decision was to go w/ the new Plasma. I was hoping to find something obvious like a crapped out cap inside, but didn't. If you can pinpoint a fixable possible problem I'd like to try it before I destroy this thing.

gerG: Plasmas are supposedly better now - banking on it! The one we got does a 'pixel rotation' where the whole picture shifts around by a few pixels a few times a minute, and also let's you invert the colors, displaying a negative image for a few minutes now and then, which is supposed to be good for it. I'm diligently babying it.

flecom said, in part:
Quote:

...clench your arse cheecks really hard.

lol... Of course this goes without saying

Peace,
Sanaka

 

[kevin gilmore]

You need to discharge the tube to the chasis of the tv. Earth ground
does not enter into this as that set most likely has a 2 pin plug anyway.
Any of the metal on the chassis works. The metal strap going across the
bottom of the picture tube works too.