TV-OUT on laptop causes major damage, fire / shock

[Duane Attaway]

Your laptop power supply is definitely to blame here.  Chances are your 
television and house wiring is correct.  There is a simple test to check:

Wall outlet: make sure the big spade has no voltage to ground (the round 
hole,) and the little spade has 120 volts to both the big spade and 
ground.

Television chassis: any exposed metal part should have 0 volts to nuetral 
(large spade on electrical outlet) and 120 volts to hot (small spade) and 
ground.  The television chassis should be wired to neutral.

There should be NO current from the DC side of the laptop power supply to 
either hot or neutral at your wall outlet!  It should be completely 
isolated up to thousands of volts.  They are isolated and supposed to be 
"hi pot" tested to determine breakdown voltage.

I repeat: there should be NO current path from your laptop power supply to 
the AC mains.  It shouldn't happen.  That means you shouldn't have 
fireworks in your living room.  You shouldn't get shocked when you play 
with your laptop in the bathtub.

Well, I lied.  There will be a stupid 1 megaohm resistor from the DC to AC 
side to bleed off static electricity.  You may be able to feel a slight 
shock from that under right conditions.  This is to prevent static 
discharges from breaking down the opto isolator inside and eventually 
smoking the power supply.  They should use grounded outlets to prevent 
this annoying trickle shock.

Unfortunately, UL and CSA don't want to listen to the public unless they 
are certified in positions of regulating authority.  So you might have to 
talk to a Professional Engineer.  Or better, just have your lawyer do all 
this for you:

https://www.ul.com/auth/regcon.cfm

Sue! Sue! Sue!  Someone needs to change the standards so we use grounded 
outlets and not this annoying resistor design.  It would have also 
prevented the disaster you have just described.

I can check your wiring and verify what happened if you like.


On Fri, 3 Dec 2004, Thomas Bruno wrote:

> Just a note the hardware involved was:
>
> Brand New Sony 27" flat screen TV from best buy
>
> Dell Inspiron 8500
> Video: Nvidia GeForce Ti4200 w/tvout
> 2.6ghz pentium 4-M
>
> On Fri, 2004-12-03 at 05:25 -0600, Thomas Bruno wrote:
>> Tonight, at roughly 10:30pm 12/02/04
>>
>>  I proceeded to plug my tvout adapter into my laptop to watch a dvd on
>> my tv.  I had just been a video from the cam corder, so the tv ports
>> were ok and so was the rca cable.
>>
>>   When I plugged it in, all I saw was a white flash. 3 of my friends in
>> the room say that the RCA cable melted, the tv smoked inside with lots
>> of white flashing inside of it, and the RCA cable was blown out of the
>> laptop TV-OUT connector.  I with a numb arm, awoke laying on the floor.
>>
>>   Looking at the rca cable, I see bare wire sticking out of where it
>> melted about 2 inches melted at each end.
>>
>>    I'm still in a state of panic/shock as to what just happened.  I will
>> be researching legal options now, as my laptop warranty ended because
>> the dell wouldn't let me renew because of a mix up, and other things
>> that have built up (like sending it in for fan swap to have it come back
>> not even turning it on),  now this.. a laptop I'm totally terrified of
>> even turning on.
>>
>>   Update to the little story,  I got a junk VCR that I have, and tried
>> to plug the RCA tv out into it. it also proceeded to fry the vcr, and
>> new rca cable.  This is a problem with the laptop.
>>
>> The thing has worked with the same tv in the past, only thing different
>> is that the laptop and tv were plugged into the same powerstrip this
>> time.
>>
>>
>>
>> Anyone have any recommendations/experiences?
>>
>>
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