Why am I getting zapped?

digamma · 12th August 2012, 10:07 AM

I built up my new computer yesterday, turned it on and entered the bios. At this point I touched a metal part of the case and got a zap, I assumed from static, as there are 7 fans in the case and the weather is very dry and windy at the moment. Then I noticed that the computer had frozen. I thought was odd so I went to press the reset button, but touched a front usb port and got another zap and the machine rebooted. This has been happening on and off since I assembled it. It has also been happening when touching some of the plastic control buttons too. It will make the machine freeze or reboot. But here's the kicker, it doesn't happen all the time. Sometimes the zaps can be minutes apart or longer. I can touch it and then touch it again a second later and get zapped, then wait a few minutes and touch it and it won't zap. I've checked cabling to make sure something wasn't earthing accidentally, but it also occurred to me that some of the metal parts I'm touching are isolated from the metal of the chassis and so it can't be getting juiced up from a leak somewhere. Help me!

looktall · 12th August 2012, 5:26 PM

remove the motherboard from the case and look where all of the motherboard stand offs are.
do they all line up with holes in the motherboard?

rainwulf · 12th August 2012, 5:28 PM

Quote:

Originally Posted by looktall

remove the motherboard from the case and look where all of the motherboard stand offs are.
do they all line up with holes in the motherboard?

That wont make zaps, that will make fire and/or fail.

zaps from the case usually indicate a leaky PSU thats allowing some 240 volt to get to the chassis.

Andy3008 · 12th August 2012, 5:35 PM

What type and how old is the psu. To get a zap as you call it you must have an earth fault in the system somewhere. Are you able to put a multimeter on the parts of the case where you get zapped to see if there is any voltage ? A mains earth fault should trip your RCD.

Creekin · 12th August 2012, 5:48 PM

sounds like u mighta jammed a molex cable in the side panel

or some other electrical fault
either way its NotGood™

first thing id do is strip it out and check for damaged cables
and
TRY A DIFF PSU!

c_hegge · 12th August 2012, 7:01 PM

I've had this happen to me with a shaw PSU once in a customer's PC at work. Like all Shaw PSU's I come across, I replaced it and blew it up on my load tester. (btw, it was rated at 860W, but exploded under 420W Load)

It turned out that the earth wire from the AC receptacle (which should be screwed to the PSU's case) was broken.

digamma · 12th August 2012, 7:34 PM

The PSU is a 750w thermaltake that was powering my previous rig 5 minutes before it was transplanted into the new one. The new case does have a fairly thick coat of paint on it, so maybe it isn't earthing properly. I'll trying screwing the screws that connect the PSU to the case down so they scratch through the paint to bare metal. Next it will be to strip and inspect and rebuild, followed by a new PSU. The thing that makes it odd is that the zaps aren't from all over the metal parts of the case, it's only from the front ports and control buttons (which are on the top and front of the case).

BTW, it is this case:Thermaltake GT Snow Edition
There are the buttons for fan speed and colour change on the top of the case, along with 2 prewired usb 3 ports and one esata port. On the front of the case there are 4 prewired usb 2 ports, front panel audio connections and the power and reset buttons. Ive got zaps from the plastic fan buttons as well as the metal usb ports and the black metal ventilation grille on the top of the case.

Sven76 · 12th August 2012, 8:08 PM

We ordered in 5 gt snow's to sell and build 4 of the 5 cases had faults from crappy fans to dodgy fan controllers / led controllers ill bet your case is the problem

Dr Evil · 12th August 2012, 10:14 PM

BlueSteel · 12th August 2012, 10:40 PM

I had a similar issue with a machine a few years back; I semi-consistently received small shocks when I touched the case/buttons of one of the machines I had here (it wouldn't always shock me, but it was only happening with that one machine).

Turned out that it was faulty earthing, in my case the earth pin in the IEC cable being used was open circuit

. This meant any fault currents had no where to go, and would consequently cause the voltage of the case to fluctuate w.r.t. earth/ground. Once I figured it was a faulty cable I was curious to see how high the chassis voltage would get (I measured it to the case of the machine next to it) - it was typically 0.5-6V with the faulty cable; however when I turned the computer on or off it would briefly spike to ~70V.
Replaced the cable and didn't receive any more shocks after that

.

digamma · 12th August 2012, 11:10 PM

Hmmm, I'll try the cable thing and see what happens there. It's all connected to a big ass 2200va compaq UPS, but I don't think earthing through that is a problem. I've checked the whole case over and the parts that are zapping me are all connected to the case/earth. Which means I think I've narrowed it down to an earthing fault somewhere. I'll check the power cable on the next shutdown.

Symon · 12th August 2012, 11:31 PM

Broken earth wire somewhere, either in the PSU itself, the socket, or in the IEC lead. It is mostly due to the filtering circuits used these days, if the connection to the mains earthing system is broken then the case will develop a voltage with respect to the general mass of earth. Sometimes as high as 120V.

digamma · 12th August 2012, 11:53 PM

I don't think it is in the PSU, as I did a continutity test all over the case, touching each panel and exposed screw and port and switch and wire, with the other lead of the multimeter on the earth pin of the PSU. All made continuity with it. In a couple of places I needed to scratch away a little paint to do it, but all the bits that go zap are connected to the earth pin on the PSU.

NNNG · 13th August 2012, 12:12 AM

The power supply doesn't output a high enough voltage to cause a zap. So it's definitely not something like a molex connector touching the edge of the case.

digamma · 13th August 2012, 6:52 PM

Seems after pulling the machine down, relaying and tidying up the cables the zapping is gone. Beats me.

I was also getting a whole lot of BSODs of various reasons, so I pulled out anything that plugged in and reseated it all, left it on prime 95 torture test all day and it was still running when I got home this evening. So I guess I finally have stability. Now, the ultimate test: Will it game?

I'm going to enjoy playing to find out (Or I'm going to pull my hair out when it locks up or BSODs again!).

12th August 2012, 10:07 AM	#1
digamma Member Join Date: Mar 2002 Location: Brisbane, Southside. Posts: 2,428	Why am I getting zapped? I built up my new computer yesterday, turned it on and entered the bios. At this point I touched a metal part of the case and got a zap, I assumed from static, as there are 7 fans in the case and the weather is very dry and windy at the moment. Then I noticed that the computer had frozen. I thought was odd so I went to press the reset button, but touched a front usb port and got another zap and the machine rebooted. This has been happening on and off since I assembled it. It has also been happening when touching some of the plastic control buttons too. It will make the machine freeze or reboot. But here's the kicker, it doesn't happen all the time. Sometimes the zaps can be minutes apart or longer. I can touch it and then touch it again a second later and get zapped, then wait a few minutes and touch it and it won't zap. I've checked cabling to make sure something wasn't earthing accidentally, but it also occurred to me that some of the metal parts I'm touching are isolated from the metal of the chassis and so it can't be getting juiced up from a leak somewhere. Help me! __________________ The ultimate weakness of violence is that it is a descending spiral. Returning violence with violence only multiplies violence, adding deeper darkness to a night already devoid of stars.

12th August 2012, 5:26 PM	#2
looktall Working Class Hero Join Date: Sep 2001 Location: morley.wa.au Posts: 17,935	remove the motherboard from the case and look where all of the motherboard stand offs are. do they all line up with holes in the motherboard? __________________ JoJoker endorses this product and/or comment.

12th August 2012, 5:35 PM	#4
Andy3008 Member Join Date: Feb 2007 Location: Paradise City 5075 Posts: 342	What type and how old is the psu. To get a zap as you call it you must have an earth fault in the system somewhere. Are you able to put a multimeter on the parts of the case where you get zapped to see if there is any voltage ? A mains earth fault should trip your RCD. __________________ DESKTOP - A10-5800k - Gigabyte F2A85X-UP4 - 8G Corsair Dominator Platinum 1866 - Hyper 212 EVO - Sandisk Extreme 240G - Seagate 1Tb - Hitachi 1Tb - Silverstone ST1000-P - Silverstone FT02 - 3 x Dell U2312HM LAPTOPS - ASUS G73JH - MSI Wind U100

12th August 2012, 7:01 PM	#6
c_hegge Member Join Date: Feb 2012 Location: Grafton, NSW Posts: 225	I've had this happen to me with a shaw PSU once in a customer's PC at work. Like all Shaw PSU's I come across, I replaced it and blew it up on my load tester. (btw, it was rated at 860W, but exploded under 420W Load) It turned out that the earth wire from the AC receptacle (which should be screwed to the PSU's case) was broken. __________________ My System: Core i5 660 3.33GHz, Gigabyte GA-P55-UD3R, 4GB Kingston DDR3 1333, 750GB WD HDD, Sony Optiarc DVD RW, nVidia GTX295 1760MB, Antec 1200 Case, Delta DPS-750CB 750W PSU, Hauppauge TV Tuner, Windows XP Pro. Last edited by c_hegge; 12th August 2012 at 7:05 PM.

12th August 2012, 7:34 PM	#7
digamma Member Join Date: Mar 2002 Location: Brisbane, Southside. Posts: 2,428	The PSU is a 750w thermaltake that was powering my previous rig 5 minutes before it was transplanted into the new one. The new case does have a fairly thick coat of paint on it, so maybe it isn't earthing properly. I'll trying screwing the screws that connect the PSU to the case down so they scratch through the paint to bare metal. Next it will be to strip and inspect and rebuild, followed by a new PSU. The thing that makes it odd is that the zaps aren't from all over the metal parts of the case, it's only from the front ports and control buttons (which are on the top and front of the case). BTW, it is this case:Thermaltake GT Snow Edition There are the buttons for fan speed and colour change on the top of the case, along with 2 prewired usb 3 ports and one esata port. On the front of the case there are 4 prewired usb 2 ports, front panel audio connections and the power and reset buttons. Ive got zaps from the plastic fan buttons as well as the metal usb ports and the black metal ventilation grille on the top of the case. __________________ The ultimate weakness of violence is that it is a descending spiral. Returning violence with violence only multiplies violence, adding deeper darkness to a night already devoid of stars.

12th August 2012, 8:08 PM	#8
Sven76 Member Join Date: Aug 2002 Location: Bundaberg Posts: 1,249	We ordered in 5 gt snow's to sell and build 4 of the 5 cases had faults from crappy fans to dodgy fan controllers / led controllers ill bet your case is the problem __________________ Character is the measure of what a man does when no one is looking...

12th August 2012, 10:40 PM	#10
BlueSteel Member Join Date: Feb 2005 Location: Petrie QLD 4502 Posts: 266	I had a similar issue with a machine a few years back; I semi-consistently received small shocks when I touched the case/buttons of one of the machines I had here (it wouldn't always shock me, but it was only happening with that one machine). Turned out that it was faulty earthing, in my case the earth pin in the IEC cable being used was open circuit . This meant any fault currents had no where to go, and would consequently cause the voltage of the case to fluctuate w.r.t. earth/ground. Once I figured it was a faulty cable I was curious to see how high the chassis voltage would get (I measured it to the case of the machine next to it) - it was typically 0.5-6V with the faulty cable; however when I turned the computer on or off it would briefly spike to ~70V. Replaced the cable and didn't receive any more shocks after that . __________________ ERROR 404 - Signature Not Found

12th August 2012, 11:10 PM	#11
digamma Member Join Date: Mar 2002 Location: Brisbane, Southside. Posts: 2,428	Hmmm, I'll try the cable thing and see what happens there. It's all connected to a big ass 2200va compaq UPS, but I don't think earthing through that is a problem. I've checked the whole case over and the parts that are zapping me are all connected to the case/earth. Which means I think I've narrowed it down to an earthing fault somewhere. I'll check the power cable on the next shutdown. __________________ The ultimate weakness of violence is that it is a descending spiral. Returning violence with violence only multiplies violence, adding deeper darkness to a night already devoid of stars.

12th August 2012, 11:31 PM	#12
Symon (Plugging your Socket) Join Date: Apr 2002 Location: Brisbane QLD Posts: 2,824	Broken earth wire somewhere, either in the PSU itself, the socket, or in the IEC lead. It is mostly due to the filtering circuits used these days, if the connection to the mains earthing system is broken then the case will develop a voltage with respect to the general mass of earth. Sometimes as high as 120V. __________________ DISCLAIMER - The mindless babble of this post does not constitute professional advice. I will not be held responsible if you choose to act on this advice. Unless I tell you to eat jellybeans, everyone likes jellybeans OCAU's self-appointed electrical safety expert - Founder of the bakasan Technical College - enrollments welcome. -- My Web Server in a Box

12th August 2012, 11:53 PM	#13
digamma Member Join Date: Mar 2002 Location: Brisbane, Southside. Posts: 2,428	I don't think it is in the PSU, as I did a continutity test all over the case, touching each panel and exposed screw and port and switch and wire, with the other lead of the multimeter on the earth pin of the PSU. All made continuity with it. In a couple of places I needed to scratch away a little paint to do it, but all the bits that go zap are connected to the earth pin on the PSU. __________________ The ultimate weakness of violence is that it is a descending spiral. Returning violence with violence only multiplies violence, adding deeper darkness to a night already devoid of stars.

13th August 2012, 12:12 AM	#14
NNNG Member Join Date: Sep 2009 Location: SE Melbourne. Posts: 1,288	The power supply doesn't output a high enough voltage to cause a zap. So it's definitely not something like a molex connector touching the edge of the case. __________________ \| i5-3570K @ 4.4 \| Z77X-UD3H \| 16GB DDR3-1866 \| GTX 570 OC \| Corsair HX620 \| Antec P280 \| 160GB X18-M G2 \| Filco TKL \| Crossover 27Q (2560x1440, IPS) \| + $900 of trades.

13th August 2012, 6:52 PM	#15
digamma Member Join Date: Mar 2002 Location: Brisbane, Southside. Posts: 2,428	Seems after pulling the machine down, relaying and tidying up the cables the zapping is gone. Beats me. I was also getting a whole lot of BSODs of various reasons, so I pulled out anything that plugged in and reseated it all, left it on prime 95 torture test all day and it was still running when I got home this evening. So I guess I finally have stability. Now, the ultimate test: Will it game? I'm going to enjoy playing to find out (Or I'm going to pull my hair out when it locks up or BSODs again!). __________________ The ultimate weakness of violence is that it is a descending spiral. Returning violence with violence only multiplies violence, adding deeper darkness to a night already devoid of stars.