Can a surge physically damage an LCD screen telly

[timhoward]

I got called to a site this morning. It has an overhead supply with a substation on the site.
Last night there was a power outage for about 2 seconds. I could find no real evidence of anything beyond this, nothing tripped or blew anywhere, and the only evidence was the usual aftermaths of losing power, such as intruder and fire alarms noting faults, computers need restarting etc.

Except - one resident was in another part of the building when it happened, and heard a loud pop from PA speakers, and then returned home to find her LCD TV screen cracked. There are no SPDs at all on the installation.

So I'm being asked was this just a freak coincidence, or are the two things related?! Any wise thoughts?

 

[littlespark]

It could, I suppose. If the surge was big enough to blow something on the circuit boards behind, the shock may have cracked the screen…

Or, they broke it themselves and don’t want to admit it.

Does the tv sit in direct sunlight? It could be down to heat.
I say that because when I worked on a caravan park, we had a new static direct from manufacturer, and it had a vinyl window sticker. The sunlight warmed up the sticker so much that it expanded, taking the window with it. We had to have the window replaced as there was a crack right across the inside pane.

 

[buzzlightyear]

One resident come home and a pop. Hammer to it more like, rubbing his hands 60 screen comeing up
.

 

[timhoward]

One resident come home and a pop. Hammer to it more like, rubbing his hands 60 screen comeing up
.

Not this resident Buzz, she’s as honest as the day is long….

Yeah I’d wondered about the heat too. I’ll probably never know for sure. She has Curry’s insurance so might get lucky…..

 

[littlespark]

She has Curry’s insurance so might get lucky…..

Vindaloo or madras?

 

[timhoward]

Vindaloo or madras?

Normally Karahi with a Cobra

 

[pc1966]

Certainly a surge could cause an electrolytic capacitor to blow and they can cause physical damage. The could be a big over-voltage of the sort a SPD would limit, but occasionally it is just a bad part so close to failure that the action of power-cycling can do it.

 

[Lucien Nunes]

I'm sceptical. My experience of equipment that has been subjected to overvoltage from a supply problem e.g. fed 400V instead of 230 or loss of 3-phase neutral, is that primary-side electroytics sometimes vent and spew their contents. But I don't recall seeing any shoot their cans off violently in modern equipment (<20 years) because larger caps usually have a controlled burst pattern embossed into the can end, making them bubble and squeak instead of pop. MOV's can blow their sides off but not really with enough force to damage the screen. And that's about all that tends to self-destruct visibly from mains-derived overvoltage. Certainly the effects should not propagate through the circuit as far as the LCD itself.

The destruction caused by lightning-strikes is a different matter but not apparently relevant here.

 

[littlespark]

And you can take everything Lucian says above as gospel…. As he’s probably tried several times to crack a screen by deliberately exposing the boards to an experimental over voltage.

 

[Baddegg]

And you can take everything Lucian says above as gospel…. As he’s probably tried several times to crack a screen by deliberately exposing the boards to an experimental over voltage.

If he hasn’t it’s now on his list

 

[Lucien Nunes]

I don't blow things up for fun. There are experimenters who post YouTube videos of stuff like that but it's not my style. I do sometimes have to fix things that other people have blown up though, or at least conduct a post-mortem so we know what the root cause was so we can avoid it again in future.

To the best of my knowledge I have destroyed two things by accidental overvoltage myself. One made a much louder bang than the other, but the quiet one was more expensive.

 

[mainline]

I'm sceptical. My experience of equipment that has been subjected to overvoltage from a supply problem e.g. fed 400V instead of 230 or loss of 3-phase neutral, is that primary-side electroytics sometimes vent and spew their contents. But I don't recall seeing any shoot their cans off violently in modern equipment (<20 years) because larger caps usually have a controlled burst pattern embossed into the can end, making them bubble and squeak instead of pop. MOV's can blow their sides off but not really with enough force to damage the screen. And that's about all that tends to self-destruct visibly from mains-derived overvoltage. Certainly the effects should not propagate through the circuit as far as the LCD itself.

The destruction caused by lightning-strikes is a different matter but not apparently relevant here.

I agree.
Any damage would be local to the switched mode power supply, there are no components on the screen itself which would cause it to crack.

If the tv still actually powers up, then it's going to likely be impact rather than anything else.

 

[timhoward]

I’m pretty satisfied now this was impact probably multiple times.
I’ve seen it now and the telly is on a wall but above a sofa and as I demonstrated tall people will hit their heads in the telly when sitting on the sofa.
Apparently someone did this the night in question too (you never get the whole story first time!)
The telly powers up and seems functional apart from a pixelated screen with lines on it.

So very unlikely to be anything to do with the brief power outage.

As an aside - this site recently had new air con fitted in the server room and as a training course got cancelled they ended up with about 10 air conditioning engineers in the area so they collectively rattled through the job a couple of weeks ago in an afternoon.

It seems all 10 assumed someone else set the “resume on power up” function and when I walked past the server room and could hear fans screaming I said “that sounds very wrong”. The door was eventually opened and it was 44 degrees in there! All the new units were off.

 

[mainline]

I’m pretty satisfied now this was impact probably multiple times.
I’ve seen it now and the telly is on a wall but above a sofa and as I demonstrated tall people will hit their heads in the telly when sitting on the sofa.
Apparently someone did this the night in question too (you never get the whole story first time!)
The telly powers up and seems functional apart from a pixelated screen with lines on it.

So very unlikely to be anything to do with the brief power outage.

As an aside - this site recently had new air con fitted in the server room and as a training course got cancelled they ended up with about 10 air conditioning engineers in the area so they collectively rattled through the job a couple of weeks ago in an afternoon.

It seems all 10 assumed someone else set the “resume on power up” function and when I walked past the server room and could hear fans screaming I said “that sounds very wrong”. The door was eventually opened and it was 44 degrees in there! All the new units were off.

The one good thing is that at least it's not your TV.

To my mind having a resume function that resumes to power off mode is silly as the priority would be to keep the place under a certain temperature, maybe a resume unless feature would be better similar to frost protection but the opposite.