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daussaulit
Forgetful

Registered: 08/06/02
Posts: 2,894
Loc: Earth
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My television is dead
#5224165 - 01/25/06 11:13 PM (18 years, 3 months ago) |
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I had turned on the TV and left it on for a few hours. I went into the other room and came back in a few more hours, and the tv was off. I tried to turn it back on, but nothing. I unplugged it for a minute, plugged it back in. I press the power button, and it makes that low hum like normal when you first turn it on. Then a half second later a loud pop sound comes from the TV and there is a thin horizontal line that is across the middle of the screen. The sound works fine, but I can't see shit. Its only 6 months old, and its a regular JVC 32 inch tv. Is it fucked? What can I do in this situation, never turned in the warranty card or bought the extended service plan.
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trendal
J♠


Registered: 04/17/01
Posts: 20,815
Loc: Ontario, Canada
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Re: My television is dead [Re: daussaulit]
#5224401 - 01/26/06 12:30 AM (18 years, 3 months ago) |
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There's something wrong with the video circuits, and judging by the loud pop it could be a short somewhere so it's a good idea to leave the set off and unplugged.
My guess is something in the vertical deflection is gone, because you still get a horizontal trace. It's also not a good idea to leave the set on like this because the beam could burn a line in the middle of the screen when it's not moving up and down like that.
It'll need to be repaired.
--------------------
Once, men turned their thinking over to machines in the hope that this would set them free. But that only permitted other men with machines to enslave them.
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Shdwstr
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Re: My television is dead [Re: daussaulit]
#5224546 - 01/26/06 01:28 AM (18 years, 3 months ago) |
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Yeah, You blew the Vertical Output section. Definately needs repair. Fortunately JVC has a 1 yr parts and labout waranty. As long as you can prove when it was bought, it's still covered!
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OJK
Stranger

Registered: 06/08/03
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Re: My television is dead [Re: daussaulit]
#5224921 - 01/26/06 04:30 AM (18 years, 3 months ago) |
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This shit is too weird - on the way home last night, I spied a JVC 32 inch TV someone had thrown out, so I grabbed it and carried it back to my flat - was that yours? Do you live in the UK?
If not, it's a hell of a coincidence.
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Seuss
Error: divide byzero


Registered: 04/27/01
Posts: 23,480
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Re: My television is dead [Re: OJK]
#5224981 - 01/26/06 05:28 AM (18 years, 3 months ago) |
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While on the subject of non-functional TV's, please let me voice a safety warning.
The voltages inside a TV are lethal, even if the TV has been unplugged. There are really two concerns. 1) If the bleeding resistor has blown, then the caps will remain charged to lethal voltages. 2) Even if the tube is properly discharged, if left idle, static electricty across the screen grid can recharge the system to lethal voltages.
I am all for fixing stuff yourself, but the guts of a TV are not something to play around with. Safety lecture over, thanks for listening.
-------------------- Just another spore in the wind.
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OJK
Stranger

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Posts: 10,629
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Re: My television is dead [Re: Seuss]
#5224991 - 01/26/06 05:38 AM (18 years, 3 months ago) |
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heh
last night, we were pretty drunk, and I was mucking around with the electronics in the back of the tv
one of my flatmates who does electronics came in and started freaking out about residual voltages and shit
definitely a good tip
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OJK
Stranger

Registered: 06/08/03
Posts: 10,629
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Re: My television is dead [Re: OJK]
#5224993 - 01/26/06 05:40 AM (18 years, 3 months ago) |
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Quote:
Safety is always of major concern when working on any device using electricity. Televisions have special circuitry that allows them to develop extremely high voltages. But it doesn't mean they are inherently dangerous to work on. With a few words to the wise you will be able to avoid the hazards. First unplug the set from the wall and then from all the other devises you have hooked up to it. And lastly don't forget to remove the antenna or cable connection. The circuit that creates the highest voltage is also the least likely to bite you.

This circuit is known as the 'High Voltage Circuit'. You can recognize it quickly by the bright red wire about ? inch in diameter. When operating, this circuit can develop voltages as high as 30,000 volts. If you get too close to the anode cap you will feel the hair on your hand start to raise. Avoiding the anode cap should keep you out of trouble. But the one proviso is that this cap can retain voltages in the thousands for a couple of weeks. More likely to bite you is the 'Flyback Transformer'. More specifically the bottom, where the pins stick through the circuit board. Voltages here are typically under 1000 volts. But since the pins are exposed the odds are higher that you may come in contact with them. Finally all electronic techs have been shocked by all of the circuit inside of a television at one time or another. The only injury I have ever heard of , or have had happen to myself. Have been when we (techs) jerk our hands or arms away from the source of the shock. Scrapes and that sort of thing. But that doesn't mean you cannot get electrocuted inside of a TV. Safety first and then comes the repair. Remove your jewelry and put on your tennis shoes. And please unplug the set! If you still feel uncomfortable just use this web site for reference only.
[ http://www.fixyourowntv.com/safety.php ]
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HagbardCeline
Student-Teacher-Student-Teacher


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Re: My television is dead [Re: daussaulit]
#5225030 - 01/26/06 06:49 AM (18 years, 3 months ago) |
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You never have to turn in those cards in order to receive the warranty. As long as you can show when you bought it, your fine.
Well for the most part anyway. I read a story some time back, about hard drive manufacturers if memory serves, that claimed the warranty was from date of manufacture. So if the device sits on a shelf for any amount of time before you purchase it, there goes some of your warranty. Hopefully some states DA's had a great time with that.
-------------------- I keep it real because I think it is important that a highly esteemed individual such as myself keep it real lest they experience the dreaded spontaneous non-existance of no longer keeping it real. - Hagbard Celine
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Seuss
Error: divide byzero


Registered: 04/27/01
Posts: 23,480
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Re: My television is dead [Re: OJK]
#5225184 - 01/26/06 08:29 AM (18 years, 3 months ago) |
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Quote:
But it doesn't mean they are inherently dangerous to work on. With a few words to the wise you will be able to avoid the hazards.
I don't know where you pulled this from, Odiumjunkie, but it is extremly bad advise. I have seen a person literally fly across the room, landing in an unconscious heap, after touching the wrong part in a high voltage circuit.
There are several standard safety precautions taken when working on televisions and he doesn't name a single one of them. Not one. Does he talk about grounding straps... nope. Does he talk about the one hand rule... nope. Does he talk about an isolation transformer... nope. Does he talk about static buildup across the screen... nope. Does he talk about the bleeding resistor, what it does, and what happens if it is shot... nope. Does he talk about voltage arcs... nope. Does he talk about the relationship between voltage, current, the bodies internal resistance and death... nope. Does he talk about never working alone... nope. I can go on, but I wont...
-------------------- Just another spore in the wind.
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Shdwstr
FSRCanada


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Re: My television is dead [Re: Seuss]
#5225332 - 01/26/06 09:43 AM (18 years, 3 months ago) |
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Quote:
Seuss said:
I have seen a person literally fly across the room, landing in an unconscious heap, after touching the wrong part in a high voltage circuit.
Been There... Done that! I was rebuilding a old 57 RCA color set (Round Picture Tube) and... being experienced and requiring the set be on to adjust it.... I remember this pretty electric blue spark, circling my arm... then waking up, about 15 ft from the bench. Apparently the opposite wall slowed down my journey... abruptly
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Boom
just a tester

Registered: 06/16/04
Posts: 11,252
Loc: Cypress Creek
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Re: My television is dead [Re: daussaulit]
#5225351 - 01/26/06 09:51 AM (18 years, 3 months ago) |
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I had no idea TV's were this hazardous until reading this thread
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trendal
J♠


Registered: 04/17/01
Posts: 20,815
Loc: Ontario, Canada
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Re: My television is dead [Re: OJK]
#5225385 - 01/26/06 10:05 AM (18 years, 3 months ago) |
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That article says nothing of the low-voltage side, which is far more dangerous. The smoothing capacitors will hold a lethal charge for quite a while. If they have been fully discharged they can regain a lethal charge over time.
The HV side may not kill most people but it can kill anyone. The low-voltage side has killed a lot of people, many of them fully trained to fix TVs.
--------------------
Once, men turned their thinking over to machines in the hope that this would set them free. But that only permitted other men with machines to enslave them.
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OJK
Stranger

Registered: 06/08/03
Posts: 10,629
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Re: My television is dead [Re: Seuss]
#5226269 - 01/26/06 02:21 PM (18 years, 3 months ago) |
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sorry, just pulled that from the link I gave. I know fuck all about fixing TVs, I'll defer to your judgement and leave well enough alone
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daussaulit
Forgetful

Registered: 08/06/02
Posts: 2,894
Loc: Earth
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Re: My television is dead [Re: Shdwstr]
#5226719 - 01/26/06 04:20 PM (18 years, 3 months ago) |
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well, its my roommates tv. so, he called up jvc, and I guess the warranty is still intact. For some reason it came with all this Canadian documentation, so I guess I read that one accidentally. The repair guy is going to come over next week and fix it.
But seriously, this incident will put me off from buying another JVC product. This was a brand new TV from Circuit City, bought in July and it broke.
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Shdwstr
FSRCanada


Registered: 02/17/01
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Re: My television is dead [Re: daussaulit]
#5226913 - 01/26/06 05:00 PM (18 years, 3 months ago) |
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Quote:
daussaulit said: But seriously, this incident will put me off from buying another JVC product. This was a brand new TV from Circuit City, bought in July and it broke.
Don't let it bother you too much. Chances are, after the repair, the circuit will be stronger than the original parts were. The fact that it screwed up within the warranty is a good thing! If it was an RCA, on the other hand... Their warranty REALLY SUCKS!
Glad it worked out for you!
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XUL
OTD Janitor


Registered: 03/16/05
Posts: 28,261
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Re: My television is dead [Re: daussaulit]
#5227479 - 01/26/06 06:41 PM (18 years, 3 months ago) |
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Television is reality, and reality is less than television.
--------------------
TRUMP 2020
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Boom
just a tester

Registered: 06/16/04
Posts: 11,252
Loc: Cypress Creek
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Re: My television is dead [Re: XUL]
#5227718 - 01/26/06 07:19 PM (18 years, 3 months ago) |
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Seuss
Error: divide byzero


Registered: 04/27/01
Posts: 23,480
Loc: Caribbean
Last seen: 3 months, 8 days
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Re: My television is dead [Re: Shdwstr]
#5229861 - 01/27/06 03:00 AM (18 years, 3 months ago) |
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Quote:
Been There... Done that! I was rebuilding a old 57 RCA color set (Round Picture Tube) and... being experienced and requiring the set be on to adjust it.... I remember this pretty electric blue spark, circling my arm... then waking up, about 15 ft from the bench.
The one I saw was from a microwave oven. We were pulling the magnetron and the guy doing the work didn't realize the circuit was still charged. It was an amazing sight... he literally shot across the room like a cannon ball... the wall stopped his flight as well.
Regarding the high voltage/low voltage stuff... when I was working with power, we always considered 32-volts to be the start of "high voltage". I don't know if this is an industry standard, but I suspect that it is. Remember, it isn't voltage or current that kill, but the bodies internal resistance.
-------------------- Just another spore in the wind.
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koppie
astral projectile


Registered: 07/23/04
Posts: 2,653
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Re: My television is dead [Re: Seuss]
#5230112 - 01/27/06 07:53 AM (18 years, 3 months ago) |
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Microwave ovens are way more dangerous than televisions, as they have to deliver 30kV at a power level of 800 watts or more. The high voltage circuit in an unplugged television may give you a nasty shock, but unless you have a weak heart they are extremely unlikely to harm you.
The most dangerous part in an unplugged television is not the high voltage system which stores very little energy, but the capacitor in the switched mode power supply (near where the mains cable joins the circuit board), which can indeed hold enough energy at mains voltage to do serious damage.
And yes I have received many electrical shocks in my life while messing with electronics both plugged in and not (If you're trying to repair a CRT monitor or TV it has to be plugged in so you can trace the problem) and the worst effect I ever suffered were sore muscles. Being careful is one thing, being phobic of electricity is going too far.
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Seuss
Error: divide byzero


Registered: 04/27/01
Posts: 23,480
Loc: Caribbean
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Re: My television is dead [Re: koppie]
#5230640 - 01/27/06 11:01 AM (18 years, 3 months ago) |
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> Microwave ovens are way more dangerous than televisions
Correct, but my story didn't involve a TV, so ...
From the Sci Electronics faq...
Quote:
TVs and computer or video monitors are among the more dangerous of consumer electronics equipment when it comes to servicing. (Microwave ovens are probably the most hazardous due to high voltage at high power.)
There are two areas which have particularly nasty electrical dangers: the non-isolated line power supply and the CRT high voltage.
Major parts of nearly all modern TVs and many computer monitors are directly connected to the AC line - there is no power transformer to provide the essential barrier for safety and to minimize the risk of equipment damage. In the majority of designs, the live parts of the TV or monitor are limited to the AC input and line filter, degauss circuit, bridge rectifier and main filter capacitor(s), low voltage (B+) regulator (if any), horizontal output transistor and primary side of the flyback (LOPT) transformer, and parts of the startup circuit and standby power supply. The flyback generates most of the other voltages used in the unit and provides an isolation barrier so that the signal circuits are not line connected and safer.
Since a bridge rectifier is generally used in the power supply, both directions of the polarized plug result in dangerous conditions and an isolation transformer really should be used - to protect you, your test equipment, and the TV, from serious damage. Some TVs do not have any isolation barrier whatsoever - the entire chassis is live. These are particularly nasty.
The high voltage to the CRT, while 200 times greater than the line input, is not nearly as dangerous for several reasons. First, it is present in a very limited area of the TV or monitor - from the output of the flyback to the CRT anode via the fat red wire and suction cup connector. If you don't need to remove the mainboard or replace the flyback or CRT, then leave it alone and it should not bite. Furthermore, while the shock from the HV can be quite painful due to the capacitance of the CRT envelope, it is not nearly as likely to be lethal since the current available from the line connected power supply is much greater.
One other concern when working inside a television... the neck of the CRT (the glass tube) is very fragile and easily broken. Although I have never seen this happen, the warning is in all of my training literature... be careful not to break the neck on the CRT... don't pick the CRT up by the neck, etc...
-------------------- Just another spore in the wind.
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