Static Shock Through USB Port - System Destroyed

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aquafloe

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Oct 24, 2007
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Hey everyone. I went to plug in my USB drive in a front USB port on my pc and it shocked it and restarted. It's done this before, but this time the LAN stopped working. It couldn't see the network or access the internet. I unplugged everything and let it sit overnight. Today I tried again and the fans slowly start turning and the decorative LEDs fade in and out. There's no response on the screen. I've read about there being physical burn marks on the MB after this kind of incident, but I found nothing. My first thought was that it was the motherboard, but now this seems like a PSU problem. I'm no good at diagnosing these things myself. Could anyone assess what's going on please?
 
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aquafloe

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Thank you very much. I know now that my PSU is dead. I ran the PSU test on it and it did nothing make a whiny-sounding frequency, sort of like a squeal. The fan didn't spin and the light didn't turn on, and the connected case fan did nothing as well.

As I mentioned in my first post, the first symptom was the LAN/Ethernet port not working. Could this be a sign that the motherboard was affected as well, or could that have been caused by a faulty PSU? I can't conduct any further tests because I don't have a spare PSU.
 
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Ubrales

Ubrales

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It's good that you have tested and confirmed that the PSU is defective.

The next step would be for you to decide whether the computer is worth repairing/re-building.

If the computer has old obsolete technology, and the replacement of the motherboard, along with other defective parts, is not economical, now may be the time for you to consider specifications and a new build to cover your present requirements as well as provide for some future expansion.

Within the last six months, most manufacturers have introduced great new products like Motherboards, Graphics cards, PSUs, etc., at attractive prices. And during this season, there are still some good deals out there.

Good luck!
 
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aquafloe

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Thanks. Before I go looking for new system options I want to make sure I can't get this one working. If my motherboard IS fried, and I DID buy a new PSU for it, could the fried motherboard ruin the new PSU? Should I buy a new motherboard along with a new PSU to ensure that everything works well?
 
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iam2thecrowe

iam2thecrowe

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unplug the front usb port, sounds like that is where the short is. In fact, you may want to take out all the components and put the motherboard, psu and bare essential components (ram, vid card) on a bench and power it up like that. If there are any short circuits to the chassis you can then rule that out, as it sounds like that may be the case. Motherboards rarely dead short, more likely something else. Rule out the simplest things first, that you can do without buying any new stuff.
 
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jsc

jsc

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Shocks are a sign that you have something wrong. That's generally a sign of a grounding problem.

You need to figure out what is wrong or the same thing can happen again.
 
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aquafloe

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I think the problem is the room itself. It's quite dry during the colder months and the carpet is high and causes a lot of static in the room. My computer is resting on a wooden crate for now, and I'm planning on getting a replacement desk for an old one I've been dealing with for a while.
 
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Ubrales

Ubrales

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The computer power plug has 3 prongs; one is the ground and is adequate. Low humidity is not the problem. Unplug the USB connector that plugs into the motherboard, and check that wiring for shorts. Are the front USB ports plugged into two separate USB pin headers on the motherboard? If this is the case, then unplug both, check for shorts, and the plug in only the good one(s).

You always have the option on relying on the rear USB ports that are directly soldered into the motherboard. One one of my old computers that had a bad front USB port, I used a USB extension cable, plugged it into the rear port and then laid the other end beside the front of the computer. Does not look cool, but it works fine.
 
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RetiredChief

RetiredChief

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ESD
ESD is a big issue during the winter monthes. There is a large jump in the ability to generate an electostatic charge when the RH drops below 30% (Will get the chart when friend returns from vacation). The RH in my office is currently 16%.
With an RH less than 30 % you can very easi;ly build up several KVs. Also at that levels you do not need to touch (or draw an arc). The E-M field can damage a unprotected component.

To explain. Your MB is normally surrounded by a case - no problem. Open the case and stick your pinky close to a IC (not close enought to draw an arc) and it is possible to damage that IC.

I would agree that grounding can be a problem, and at 70 F and RH=>50% and you get a shock then grounding would be a good possibilty. But if you did not get sapped at High RH and now are getting zapped (RH less than 30%) most probable cause is ESD. If the RH drops below 30%, I can not work on flight Hardware system.

The wooden box under the Computer is great for reducing dust buildup inside the computer, but does nothing for preventing ESD problems.

As to checking out the system, I agree with removing the system from the Case (at least disconnecting the front panel ports and tring to find out which parts are "DOA"
 
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popatim

popatim

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ESD is amazing. Motorola showed us a microporcessor board under a microscope and then passed it around the class and put it under the scope again. It looked like the cratered surface of the moon when it was done.

On high static days like you have, make a habit out of touching the metal case often or wear a ground strap wrist band. I've heard of some psu being isolated from the case with rubber bushings to reduce noise, if yours is like this then install a wire from the psu case to the pc case chasis. Metal to metal of course.

Lastly have your outlet checked. this is an inexpensive device you plug into the outlet and it will test the 'circuit' . like ths one:
http://www.amazon.com/Gardner-Bender-GFI6302-Receptacle-Tester/dp/B000RUL2UU
 
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iam2thecrowe

iam2thecrowe

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but, is static really going to jump from your hand, which is grasping a usb device, into one of the dc lines (rather than ground) through the usb controller and reboot the computer and cause it not to start up again??? I still say its much more sinister than just static.
 
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Ubrales

Ubrales

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Very high voltages will ionize the surrounding air, thereby creating a conductor. This is known as 'corona' and is sometimes visible on a dark night as a faint glow. This is why high voltage transmission tower repair crews are trained not to come too close to a potential hazard (They don't need to physically touch the hazard).

Static discharges inside a home with low humidity is sometimes visible as a spark. High voltage, ultra low amps. Not enough to damage humans, but sometimes enough to damage ICs and other sensitive electronic devices. This is why Class 1 clean room mandate the use of anti-static gowns, caps, hoods, as well as grounding devices for personnel. Before entry, there is a check station to verify the effectiveness of the ASD.
 
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RetiredChief

RetiredChief

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Also applies to class 10,000 clean rooms. Most cleanrooms also controll the RH. Our's has a hard time maintaining 35 -> 40 % (65 F) during the winter. Also most sensitive equipment also require an ionizer.

3500 Volts (and higher) is not an uncommon charge on a individual when RH is below 30%. At that level the E-M field can cause damage to unprotected components. Being mounted on a circuit board is not protective, Being inside a metal shield such as a case is.
 
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popatim

popatim

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We just got in a new 1.3million dollar IBM mainframe in here at work, You don't need to be in a clean room to have an RH controlled environment. We've got 4 big units to cool the room and maintain humidity at 35%. 3 units are 4'x4'x7' and the forth is 3'x10'x7' LOL
 
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wills55

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I think it is static. I have this problem at my place too: new carpet, northern Idaho winter. When I touch anything grounded, I invariably shock myself. You can year the pop. When I plug in headphones, phone charger, or usb drive, the computer instantly freezes.

Here's my fix (I haven't fried my computer yet). I set up a metal desk lamp on top of the computer case. I touch this to discharge my static before I plug anything in. Problem solved.

I'm pretty sure of it, because (stupidly) I actually tested my theory by deliberately collecting static and plugging things in, crashing my computer, rebooting, and then doing it all over again but discharging the static before touching the computer. (This has been going on for a while, so how much harm can a couple more instances do?)

Unfortunately, I already RMA'd a really nice card reader/front I/O port thinking that was the problem (first time builder, didn't know any better).
 
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wills55

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BTW, it is best to plug the (grounded) lamp into the wall outlet directly, so that the ground path does not go through your surge protector or ups unit, but instead goes strait to the ground.
 
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