Thunderbolt port blew up

[dcphilly]

I think I screwed myself by buying a 3rd party chinese cable....

I have a late 2012 iMac. I bought an external monitor yesterday (Asus VG248QE). I bought a mini displayport to displayport cable so that I can use the monitor at 144hz. The cable is QVS 6.5ft model #MDPDP-2M from Microcenter for $15.99. It was working fine yesterday.

I wanted to have a more permanent set up so today I unplugged everything so that I can use both monitors comfortably. These are exact steps:

1) plugged in ASUS monitor power to wall.
2) plugged in ASUS monitor to imac.
3) plugged in imac power to wall.

The power socket started sparking up and the thunderbolt port also sparked up. This happened for a good 1-2 seconds (however long it is natural reaction to pull out plug). I'm considering what my next steps should be...

BTW the iMac turns on and loads but it makes a flickering sound and smells so I'm keeping it turned off.

pictures coming soon.

 

[dcphilly]

pictures below

 

[dcphilly]

more pics

 

[Nightarchaon]

all i can say is

Holy Crap

is there anything left of the cables connector in the port ? get some pliers and get that out.

Hopefully the burning and soot is from the cable , not the iMac and at worst you just lost your thunderbolt port...and not your whole logic board around the ports.

on a side note, i bought an expensive "official" thunderbolt cable, and those things get SCARY hot, so much in fact that ive stopped using thunderbolt completely because i was too scared to leave them connected unattended.

So i can see why a shoddy 3rd party one would explode if the official ones barely keep from melting.

 

[dcphilly]

A piece of the cable is still in the port. I think what I'll do first is make a Genius Bar appointment for tomorrow and let them know what happened. Then ask to see if they think it's still safe to use if I just remove the pieces still inside.

 

[DeltaMac]

Be sure to test your wall socket for proper connection and grounding. A simple test light will tell you everything, or get an electrician to check for sure.

I suspect that you should have had everything connected through a surge protector, which _might_ have killed itself (and possibly saved your other equipment).

DON'T try to use your iMac. Take it to a repair shop.
Same for the Asus monitor.
There's some good reasons, I think, that the Thunderbolt cables haven't come down much in price, and that's the internal tech that is part of the cable. If that's not done correctly, trying to keep the cost down - well, there you are.

The piece that is left inside the port may be welded in place - and may not be repairable…. Another good reason to get to a shop...

 

[dcphilly]

I know for certain that the outlets are working properly. I bought this place 3 months ago and the home inspector that I hired tested all the sockets. I was there when he tested this specific one.

I think I'm going to return the asus monitor along with the cable to micro center.

 

[DeltaMac]

Moving forward:
Don't forget to get . a . surge . protector !

 

[drambuie]

I can't offer an opinion on the health of your iMac, but from the photos, and the order of connection it's obvious what happened. The pitted pins on the iMac's power cord are the ground and neutral, and it looks like the ground connection on the TB/displayport plug is fried. The only way this could happen would be if the monitor's ground connection was somehow connected to the 120v hot line, so the ground through entire system was hot, and when you plugged the iMac in, it shorted to true ground with fireworks. You're lucky you didn't electrocute yourself.

Either there's a problem with the power outlet the monitor was connected to, or there's a power wiring error or short in the monitor. You didn't say if the monitor uses a two prong, or three prong plug.

 

[dcphilly]

The monitor uses 3 prong. Does that mean it's a faulty wall outlet?

I remember the home inspector used this handheld plugin to test each socket. They were all fine at the time.

 

[hfg]

I can't offer an opinion on the health of your iMac, but from the photos, and the order of connection it's obvious what happened. The pitted pins on the iMac's power cord are the ground and neutral, and it looks like the ground connection on the TB/displayport plug is fried. The only way this could happen would be if the monitor's ground connection was somehow connected to the 120v hot line, so the ground through entire system was hot, and when you plugged the iMac in, it shorted to true ground with fireworks. You're lucky you didn't electrocute yourself.

Either there's a problem with the power outlet the monitor was connected to, or there's a power wiring error or short in the monitor. You didn't say if the monitor uses a two prong, or three prong plug.

That was going to be my comment as well. Looks like you possibly have a ground fault through the other monitor and it resolved itself through the cable.

 

[SaSaSushi]

on a side note, i bought an expensive "official" thunderbolt cable, and those things get SCARY hot, so much in fact that ive stopped using thunderbolt completely because i was too scared to leave them connected unattended.

That is strange.

I'm using a TB cable manufactured by Sumitomo Electric here in Japan with an external SSD enclosure I run OS X from. I'm not sure what "official" means but mine never gets more than slightly warm to the touch at the plug. The cable itself doesn't even get warm.

 

[cynics]

The monitor uses 3 prong. Does that mean it's a faulty wall outlet?

I remember the home inspector used this handheld plugin to test each socket. They were all fine at the time.

Unlikely. I think the only reason there is damage on the plug and outlet is because you plugged and unplugged it in when it was in the process of shorting out. That would cause an arc and the damage on the plug.

It would be extremely difficult to wire an outlet to be destructive on purpose let alone on accident. Reversed polarity is about the worst thing that you can do.

I reread your OP a couple times but am still a bit unclear. You got the monitor and cable yesterday, and had it working? Then went and rearranged some stuff and when you went to plug it back in is when it fried? Or am I misunderstanding?

 

[Silvrbill]

I'm thinking the TB cable didn't seat correctly and caused a short at the TB plug. When you plugged in the Imac (and then turned it on?) it obviously caused a short at the TB port.
That would explain the damage at the TB port and the damage at the 3-prong Imac power plug.

 

[dcphilly]

I reread your OP a couple times but am still a bit unclear. You got the monitor and cable yesterday, and had it working? Then went and rearranged some stuff and when you went to plug it back in is when it fried? Or am I misunderstanding?

Yeah, that's what happened. I had it working yesterday. The desk was cramped so I had to rearrange the imac and monitor so both would fit.

 

[ScottishCaptain]

I know for certain that the outlets are working properly. I bought this place 3 months ago and the home inspector that I hired tested all the sockets. I was there when he tested this specific one.

I think I'm going to return the asus monitor along with the cable to micro center.

Home inspectors are idiots. I can't even begin to describe all the things ours missed when we bought our place (or willingly chose to ignore). You cannot rely on them to tell you anything- other then that the building is still standing.

I have only ever seen this kind of damage once before, and that was when an electrical fault lit up the ground line with 120VAC. The damage to the equipment (an audio studio in this case) could best be described as "explosive"- numerous components erupted in flames, others simply obliterated themselves into various charred fragments.

The fact that your grounding pin has arc marks on it (!) tells me that there is something direly wrong with that outlet. You are risking your own life by ignoring the possibility that you have a severe ground fault somewhere in your house. If there really is 120VAC across that terminal, it means that any metallic appliance that you have plugged into the same circuit is going to have a live chassis as well. This could kill you if you touch it.

Seriously. Get your electrical checked out. Catastrophic explosive failures like this should NOT be taken lightly.

Edit: I suppose it could be the PSU on the monitor as well. Either way, it looks like 120VAC got somewhere it shouldn't be- either from the grounding pin on the socket your iMac was plugged into, or the socket your monitor was plugged into, or possibly from a severe short inside the monitor PSU. The fact that the iMac still kinda works tells me that it probably didn't come from the computer. Either way, I'd still recommend that you check out those outlets just to be sure. If you do track down the problem, I'm sure the respective company would be very interested in hearing from you since this sort of thing is never supposed to happen.

-SC

 

[dcphilly]

Thanks for the input. I'll call an electrician on Monday.

 

[hfg]

You can get simple little outlet testers at hardware stores which will indicate if the outlet is wired correctly. I don't think they will reliably indicate a faulty or open ground however.

 

[joe-h2o]

I'm thirding the comments that this is an extremely serious grounding fault.

The damage evident on the earth pin of your iMac's plug is a give-away that you had a serious short to ground - no small kidding here, but your iMac saved your life (or at the very least saved you from a painful electrocution injury), since somewhere in your hardware you had something that should have been at ground potential floating at 120V.

I suspect that the monitor has an earth fault, since the path of the current seems to have been from the monitor, via the ground connection on the TB cable and then through the grounding pin on the iMac, so if there's a short in the monitor it *wasn't* run safely to ground for some reason.

What should have happened was that the monitor should have shorted to ground instantly when you plugged it in (you said it had a three pin plug) but it clearly did not do so.

I imagine that it all worked earlier in the day, then you moved the monitor and something inside moved (maybe a frayed cable or a loose connection) that created the short condition that made the chassis live when you plugged it in, that was not safely run to ground due to poor wiring or a lack of grounding safety (it might not even have the earth pin connected to anything).

Your iMac absolutely *does* have a meaty ground connection, as you have noticed.

The source of the fire and smoke is down to the TB cable not being rated to pass 120V AC at 10 amps and simply melting and overheating.

What I'm curious about is that your house electrical system should have detected the fault right away and tripped the circuit breaker that feeds that socket. This is a major red flag to me for safety and I suggest that you check that out *immediately* - you say you're getting an electrician in. Have him check this specifically, not just that the sockets are wired correctly. It's possible that the thunderbolt cable acted as a big enough resistor to keep the current flowing to ground below what the circuit breaker is designed to detect and cut off, but I doubt it (I can't imagine the resistance of the ground shield in the cable is very high at all).

Ground faults like this (and the circuit breaker/RCD not tripping) are a fire risk, as well as an electrocution hazard. Please have your house properly inspected by a qualified electrician.

 

[cynics]

I'm thirding the comments that this is an extremely serious grounding fault.

The damage evident on the earth pin of your iMac's plug is a give-away that you had a serious short to ground - no small kidding here, but your iMac saved your life (or at the very least saved you from a painful electrocution injury), since somewhere in your hardware you had something that should have been at ground potential floating at 120V.

I suspect that the monitor has an earth fault, since the path of the current seems to have been from the monitor, via the ground connection on the TB cable and then through the grounding pin on the iMac, so if there's a short in the monitor it *wasn't* run safely to ground for some reason.

What should have happened was that the monitor should have shorted to ground instantly when you plugged it in (you said it had a three pin plug) but it clearly did not do so.

I imagine that it all worked earlier in the day, then you moved the monitor and something inside moved (maybe a frayed cable or a loose connection) that created the short condition that made the chassis live when you plugged it in, that was not safely run to ground due to poor wiring or a lack of grounding safety (it might not even have the earth pin connected to anything).

Your iMac absolutely *does* have a meaty ground connection, as you have noticed.

The source of the fire and smoke is down to the TB cable not being rated to pass 120V AC at 10 amps and simply melting and overheating.

What I'm curious about is that your house electrical system should have detected the fault right away and tripped the circuit breaker that feeds that socket. This is a major red flag to me for safety and I suggest that you check that out *immediately* - you say you're getting an electrician in. Have him check this specifically, not just that the sockets are wired correctly. It's possible that the thunderbolt cable acted as a big enough resistor to keep the current flowing to ground below what the circuit breaker is designed to detect and cut off, but I doubt it (I can't imagine the resistance of the ground shield in the cable is very high at all).

Ground faults like this (and the circuit breaker/RCD not tripping) are a fire risk, as well as an electrocution hazard. Please have your house properly inspected by a qualified electrician.

The outlet isn't a GFCI or AFCI so the damage is only going to be limited to the outlets breaker size. Which assuming this is in the US (judging by the looks of the outlet) is likely a 15 amp breaker. Thats the potential of 1800 watts @ 120v without tripping the breaker, which can do far more damage then pictured (which always looks worse then it is when it comes to electrical failures, a little bit of soot makes a huge mess).

While I still think its a good idea to have a professional check everything out and at the very least replace that damaged outlet I doubt they will find anything.

In my years of working on electronics I've seen much more damage then this without tripping breakers or anything. And while GFCI and AFCI breakers and sockets are nice in this circumstance the OP would have just taken the iMac to a different outlet and it would have burned up there like most people do.

EDIT: The reason I say that is because "what changed", it was working then it wasnt. Really the only thing he did was unplug and plug stuff back in. If it was the electrical outlet a short would have likely been a dead short and tripped the breaker. However the TB connection is a lot more susceptible to damage and could cause a short that is enough to burn it up without overamping the breaker.

 

[Silvrbill]

I'll bet there is nothing wrong with the outlet. I think the TB cable got damaged resulting in a short. That's why the TB port is burnt and the prongs on the power cord too. The cable caused a direct short, either to neutral or ground when the computer was plugged in.
Nothing wrong with any other outlets are there?
Never had this problem before have you?
The problem is associated with the TB cable, not the outlet.

 

[ScottishCaptain]

I'll bet there is nothing wrong with the outlet. I think the TB cable got damaged resulting in a short. That's why the TB port is burnt and the prongs on the power cord too. The cable caused a direct short, either to neutral or ground when the computer was plugged in.
Nothing wrong with any other outlets are there?
Never had this problem before have you?
The problem is associated with the TB cable, not the outlet.

Say what?

TB does not carry enough power to yield that kind of damage. Even if you cut a cable open and shorted out all the pins together, at a minimum you'd blow the poly fuse on your motherboard, worst case you'd fry your TB controller and the PSU would shut down the computer. There is no way that Thunderbolt (or any other I/O expansion bus for that fact) would have passed regulations if one of the possible failure modes was "explode".

-SC

 

[2984839]

A piece of the cable is still in the port. I think what I'll do first is make a Genius Bar appointment for tomorrow and let them know what happened. Then ask to see if they think it's still safe to use if I just remove the pieces still inside.

My guess is there is zero chance they'll say it's safe to use. It's a liability thing more than anything else. Their lawyers would have heart attacks if they told a customer it was safe to use a device that was just involved in a potentially fatal grounding problem.

 

[Silvrbill]

Say what?

TB does not carry enough power to yield that kind of damage.
-SC

It doesn't need to carry lots of voltage to cause a failure like we see. It only has to provide a path to ground or neutral for current.
i've seen a 12v clearance light burst into flames on a vehicle, only 12v but a direct short to ground.
If there was something wrong with the outlet the breaker on the circuit would have been tripped.
The neutral and ground are bonded together in the MDP (and other places).
Any direct short to ground or neutral in the outlet would trip the circuit.

 

[joe-h2o]

It doesn't need to carry lots of voltage to cause a failure like we see. It only has to provide a path to ground or neutral for current.
i've seen a 12v clearance light burst into flames on a vehicle, only 12v but a direct short to ground.
If there was something wrong with the outlet the breaker on the circuit would have been tripped.
The neutral and ground are bonded together in the MDP (and other places).
Any direct short to ground or neutral in the outlet would trip the circuit.

The Thunderbolt spec is 18 V at 550 mA. If you shorted that to ground you wouldn't get this sort of damage - the and the Thunderbolt controller would shut the port down. The sort of arc damage on the earth pin of the iMac's plug is not from an 18 V DC source running at half an amp.

This looks like a grounding fault. The proof will be in the pudding - if the new monitor is opened up, I bet the earth is not connected internally, or there's a break somewhere in the flex.