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

 

[Richard Burns]

I cannot remember the sequence but on connecting the power supply to a laptop, there are usually instructions to say either plug into laptop before mains or vice versa.
Since you put power to the transformer first it seems like this was the wrong way round.
I think the transformer when powered can build up a charge on the output that is transferred to the laptop on connection.
However all this is vaguely remembered details so could be rubbish, however I think that is the area that you need to consider.

 

[Resu]

As Richard has said. It was more than likely a coincidence that it happened when you first tried connecting your laptop to the TV.

 

[g1190]

Thanks for your help Richard, I really appreciate it. I take full responsibility for what happened if indeed it was my actions that caused the damage. However, I know many people, myself included that will connect a plugged in AC adapter to an already on, laptop. I cant figure out how adding an hdmi cable into the mix could have caused such damage.

The reason I ask the question is the repair of the motherboard will be costly unless I can ascertain whether or not either the TV or the laptop was somehow faulty before this event.

Thanks again Richard, and any other responses are most welcome

 

[g1190]

hi resu, thanks for your input.
should I just take it that I'm really unlucky? and there was a million to one chance of this happening?

cheers

 

[Richard Burns]

As I say I can't really remember where I saw it but I think it was in the instructions to my laptop (bought five years ago!).
I think that this would in general be considered a dangerous situation to have designed in to a power supply, so I expect it would not happen often.
If you were to state that the power supply output was unstable then this would likely be the case.

 

[Plonker 3]

Think you would be better getting a independent person who knows about these sort of things to look into this. Maybe even dig out or search the interweb for instructions for both your TV and laptop to ascertain as Richard said if there is a "correct" way to connect the appliances together.

 

[g1190]

thanks dillb,

i suppose an additional reason to solve this issue would be so that i know if perhaps the hdmi port on the tv has a fault, so as not to connect anything else to it.

cheers

 

[g1190]

just checked the laptop manual for instructions on how to connect to tv via hdmi

1 Plug the power cord of your TV (1) into an AC outlet.
2 Plug one end of an HDMI cable (2) to the HDMI output port (3) on the computer and the other end to the TV.
3 Switch the input channel of the TV to external input.
4 Set up the TV configuration system

no mention of having the laptop plugged in.will have to check the tv manual now.

 

[telectrix]

think it's a case of spilling beer onto the laptop and then phoning insurers.

 

[Richard Burns]

I have manged to find my laptop instructions (from 2006) and it is not clear cut but does say plug into computer before AC power but does not say why.
However this is probably very out of date now.

 

[DPG]

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

 

[g1190]

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

 

[Silly Sausage]

think it's a case of spilling beer onto the laptop and then phoning insurers.

Too late, sounds like he's got a repair man involved now.
I'd have had it straight back to the shop under warranty!
I can see the attraction of all this Wifi nonsense now.

 

[g1190]

yes, unfortunately the laptop was just out of its warranty. I haven't submitted it to sony yet though. I have just been dealing with them over the phone to see what my options are now.

 

[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.