help needed after laptop exploded when using hdmi cable

[g1190]

hi,

thanks in advance to any help you can offer.

recently, for the first time, i attempted to watch a film through my laptop connected to my television. i connected my latop to my sony flatscreen telly with an hdmi cable. the tv was plugged in and on; the latop was on but NOT with its ac adapter plugged in. no problems here. i then decided to connect the latop to its ac adapter and there was a flash, bang and smell of burning. i turned off the computer immediately. it turned out the motherboard was fried. the tv was fine, as was the hdmi cable. but what im searching for is the answer to why this happened. where could the fault have been, and in which appliance?

thanks very much

dave

 

[DPG]

i thought it wouldnt matter which order i plugged them in too. so does that perhaps mean the fault could lie in the tv, or in the cable i used? the sony repair guy said something about earthing, and the tv, but i cant remember what it was. glad you mentioned it though

thanks

The cable won't have been faulty, or at least it's very unlikely. Many TVs (and other hifi/video equipment for that matter) are not earthed, and have a voltage present on the shielding of the sockets. You may have had a tingle off aerial sockets on TV's, satellite receivers before which is caused by the same thing. Class I devices (ie. ones which have a mains earth connection in the plug) should not suffer from this. There is often advice about switching things off before connecting them to other devices - this is the reason for this. I'm surprised it damaged the laptop though, and I would be having strong words with Sony about this. Daz

 

[g1190]

Right I understand you now. Actually I used to get minor electric shocks from touching metal screwy parts connected to the virgin box the tv was connected to. when i updgraded my box, the technician got a shock too and said it shouldn't be happening. i guess the two things are linked. i guess the tv must be the cause.


thanks again

 

[DPG]

Right I understand you now. Actually I used to get minor electric shocks from touching metal screwy parts connected to the virgin box the tv was connected to. when i updgraded my box, the technician got a shock too and said it shouldn't be happening. i guess the two things are linked. i guess the tv must be the cause.


thanks again

Yep, most of the satellite tv boxes used to be the same - probably still are. You can sometimes actually see a small spark if you touch an earthed cable to the sockets. Daz

 

[g1190]

thanks for you help DPG. do you think its worth my while getting in an electrican to determine if the tv is faulty, or do i just accept that this sort of occurrence is an unfortunate but inevitable part of the ownership of electrical products

 

[Marvo]

I think it would be worth getting an experienced electrician to test the plug circuits and the external earth impedance. It wouldn't take long (maybe 30 mins to an hour) and it might save future damage to other electronic equipment.

 

[Darkwood]

What film was it? The Lawnmower Man!

 

[shanky887614]

It shouldn't matter which order you plug them in - I don't get that at all. The only thing I can think is that if there is a voltage on the earth of the tv connectors (which there sometimes is on non class I TV's, etc.) and the shield of the hdmi connector maybe touched the data pins of the socket and thus applied the voltage to them. The design of the hdmi socket makes this unlikely though. Daz

the power should be separate for the video output on the device.

its likely the transformer in the laptop failed.

the charger charges at say 15-20v but things like usb devices run on 5v and cpu's run on 12v.


it wouldn't have made a difference if it was plugged in or not, it still would have gone bang.

probably a faulty leed

 

[DPG]

the power should be separate for the video output on the device.

its likely the transformer in the laptop failed.

the charger charges at say 15-20v but things like usb devices run on 5v and cpu's run on 12v.


it wouldn't have made a difference if it was plugged in or not, it still would have gone bang.

probably a faulty leed

I know the voltages on USB ports are 5V and chargers are generally around 19V (modern CPU's don't generally run on 12V though). The point I was making is that the shielding around the connectors of some pieces of audio/video equipment is often floating at a highish voltage, rather than being truly earthed. Try it, you might be surprised. Daz