Static discharge on grounded Computer Case crashes computer, theories on why and how can I fix it?

Thread Starter

forlemon

Joined May 17, 2021
3
Hello! Lately my computer has been having a strange behavior. It crashes when I touch it, but very specifically when I touch it after getting up from my chair, while I have my rubber sandals on, because when I do it barefoot, nothing happens. This gets worse the drier the air is.

This makes me conclude that I discharge static to my computer. Now, if the case is grounded, and being a giant metal box, I suppose the components should not be affected by the discharge. But they are affected, since the crash. By the loud fan noise of the graphics card and the loss of image I think it might be affecting the graphics card, but I could be completely wrong here.

Now the questions:
First, should I even be discharging and sometimes be feeling a shock when I touch the case, being the case grounded?
Second, is there any grounding problem that can cause this type of behavior, or a short?
Third, can this just be that electronics are sensible to static electricity and I should avoid touching it after getting up?

Being a software engineer, I am a complete noob at electronics, so I come here to ask for opinions or some insight about this, if anyone got some experience dealing with this kind of stuff.
If any of my assumptions were wrong, feel free to tell me and correct me, I just want to understand how and why this happens.

Thanks!
 

MrChips

Joined Oct 2, 2009
23,536
Your problem is not a grounding problem - it is lack of grounding.

There are two easy solutions.

1) Wear an antistatic grounding strap that is properly connected to a reliable ground every time you approach and use your computer.
1621299440626.png

Edit: In the photo above, the wrist band is too loose to be of much use and of course the alligator clip needs to be connected to a proper ground. (We know it's just a photo for a demonstration.)

2) If you don't want to be continuously wire, have a metal frame somewhere that is grounded. Touch a bare metal part on the frame before you approach the computer or if you tend to shuffle around in your chair or take off or put on a sweater or other garment.
 

DickCappels

Joined Aug 21, 2008
7,442
It could be that some of the discharge current is going to ground through a peripheral and on its way to the peripheral it crashes the computer. You could try unplugging peripherals one at a time to see if one in particular is making the problem. If you find one peripheral that is the source of the problem you can try powering it through an extension cord to reduce the current over that path, and even try winding the extension cord around a ferrite rod if you can get one.

Maybe a better solution is to do as I do - stay in my bare feet while at the computer.
 

MaxHeadRoom

Joined Jul 18, 2013
23,123
The PS common of a desktop or tower PC is earth grounded by virtue of the 3 pin power cord, the isolated PS DC voltage commons and MB ground plane are re-referenced to the supply GND conductor via the MB fixture screws.
So both enclosure and PC peripheral device power should be earth grounded via this method.
.
 

Tonyr1084

Joined Sep 24, 2015
5,991
Ungrounded outlet or damaged IEC cable?
That is my first thought. Either the outlet you're plugged into is not grounded or the cord may be bad.

Back in the 80's we (the company I worked for) were building a module that seemed to always fail at final test. ALL grounding was tested (except the extension cord). One day, while inspecting the work, I had my hand on the long metal plug (six outlet type) and my other hand on the steel casing into which the module was installed. I felt an AC charge when I touched one of the metal rivets. Measured the voltage and it was 67 volts AC. The test computer was plugged into the bad extension cord (if memory serves clearly) and there was an induction of stray AC volts, which when the board and sensitive component were touched by a properly grounded soldering iron - ZAP! It was only when I accidentally touched a grounded outlet and the module (which wasn't grounded) that the cause was identified. The cause - - - bad ground in an extension cord.

You may not have an extension cord, but whatever your computer is plugged into - it's no longer properly grounded. I'd bet half my paycheck on it. Half because I'm not 100% sure that's the issue. But it's a very strong and likely culprit.
 

Thread Starter

forlemon

Joined May 17, 2021
3
First and foremost, thanks everyone for the insight and sugestions! I really appreciate everyone's opinion and help.

For now the solution to avoid discharging to the computer when I touch it (I put my headphone on a stand on the side of the computer) is getting up from the chair barefoot, like DickCappels suggested.
Maybe a better solution is to do as I do - stay in my bare feet while at the computer.
But I really wanted to try and fix this issue, if there is an issue.
If ground might be the problem, how can I test it? Using a multimeter? What would be the correct procedure?

And if it is properly grounded, even if I sometimes get zapped by a static discharge when I touch the case, no component should be affected and the pc should not crash, right? Or worse, should I even get zapped?

Am I grounding the computer or is the computer grounding me?
 

MaxHeadRoom

Joined Jul 18, 2013
23,123
You are probably grounding the PC!:oops:

If you have a meter, check between both power pins and the earth pin on the socket for 120v (if N.A.)
One other way if you have a test lamp, i.e. a ES/lamp socket with pigtails, do the same test and check for lamp lighting, as long as the socket is not GFI, otherwise it would trip on that test.
 

dl324

Joined Mar 30, 2015
12,871
And if it is properly grounded, even if I sometimes get zapped by a static discharge when I touch the case, no component should be affected and the pc should not crash, right? Or worse, should I even get zapped?
If the computer is grounded properly, you can still get zapped by static electricity.

You can check the outlet with a DVM but, since you're asking these questions, you should use an outlet tester:
outletTester.jpg
You don't need the GFCI check option.
 

DickCappels

Joined Aug 21, 2008
7,442
The plastic sandals being a necessary part of the crashing suggests that the computer is grounded and you are building up a charge with the sandals that is discharged through the computer. Did you read the part about the discharge possibly going through a peripheral? It suggests a way of testing that possibility and what might solve the problem.

Quick check: Does your computer have a grounded power plug?
 

Tonyr1084

Joined Sep 24, 2015
5,991
For me it's the principal of the Faraday Cage. Your car, an airplane, any metallic surrounding structure acts as a Faraday Cage. It conducts static energy, which is what lightning is, around occupants inside the vehicle. That's why lightning does not affect airplanes (generally speaking). There may be a rare case where lighting actually knocked out some crucial electrical system, but in general, it's extremely rare.

Your computer metallic case is a cage too. When you touch it all static energy should be conducted around the innards and conduct the static charge to ground. IF NOT grounded - the energy has no where to go except to find a pathway to the neutral line, which is also connected to a ground in a round-about way. This alternative pathway could trick the power supply to detect a fault and shut it down. You said "Crash the computer". You haven't described the full details of what happens other than to use the word "Crash". I wonder if you're using a general term rather than an expressive term that describes fully what happened. I've heard people call all kinds of electrical faults as a "Short". "Short" only refers to a single sort of event where an electrical pathway finds a "short cut" back to the source. For instance, shorting a battery means instead of passing electrons through an electrical circuit it conducts back upon itself. However, a broken wire, sometimes mistakenly called a short, is actually a failure of the circuit to conduct electricity in the designed way. There are many ways a pathway can be "Open". For instance; an Open ground can allow a device to still function seemingly normally. But when introduced to a sudden source of extreme voltage that voltage can seek a way to ground - as static typically does. Through the neutral line - or even through the HOT line, though neutral at the transformer on the pole is also connected to earth ground.
 

anniel747

Joined Oct 18, 2020
1,122
The plastic sandals being a necessary part of the crashing suggests that the computer is grounded and you are building up a charge with the sandals that is discharged through the computer. Did you read the part about the discharge possibly going through a peripheral? It suggests a way of testing that possibility and what might solve the problem.

Quick check: Does your computer have a grounded power plug?
Or grounded thru a peripheral?
 

Thread Starter

forlemon

Joined May 17, 2021
3
I might borrow a multimeter to check ground or even get an outlet tester.

Quick check: Does your computer have a grounded power plug?
Yes I have a grounded power plug, EU plug. I got everything connected to a power strip, 2 monitors, router, speakers and some lights. It's a pretty old setup, never had problems, this just started to happen with this new pc. The pc I had before sometimes crashed when I plugged something on the USB port on the front IO now that I think about it.

You said "Crash the computer". You haven't described the full details of what happens other than to use the word "Crash".
Sorry, you are right, I did not explain. The screens go black, graphics card fan ramp up to max. It stays on like that, no response, just black screens and graphics card ramp up. This makes me assume it is the gpu crashing.

Having said that, is it possible that the pc isn't correctly grounded, so it is being grounded by the graphics card connected to the monitors? So when I discharge, it crashes?
 

MrChips

Joined Oct 2, 2009
23,536
Having said that, is it possible that the pc isn't correctly grounded, so it is being grounded by the graphics card connected to the monitors? So when I discharge, it crashes?
That appears to be the most likely scenario, i.e. there is a missing ground connection somewhere (especially the one to the human).
 

BobaMosfet

Joined Jul 1, 2009
1,776
Hello! Lately my computer has been having a strange behavior. It crashes when I touch it, but very specifically when I touch it after getting up from my chair, while I have my rubber sandals on, because when I do it barefoot, nothing happens. This gets worse the drier the air is.

This makes me conclude that I discharge static to my computer. Now, if the case is grounded, and being a giant metal box, I suppose the components should not be affected by the discharge. But they are affected, since the crash. By the loud fan noise of the graphics card and the loss of image I think it might be affecting the graphics card, but I could be completely wrong here.

Now the questions:
First, should I even be discharging and sometimes be feeling a shock when I touch the case, being the case grounded?
Second, is there any grounding problem that can cause this type of behavior, or a short?
Third, can this just be that electronics are sensible to static electricity and I should avoid touching it after getting up?

Being a software engineer, I am a complete noob at electronics, so I come here to ask for opinions or some insight about this, if anyone got some experience dealing with this kind of stuff.
If any of my assumptions were wrong, feel free to tell me and correct me, I just want to understand how and why this happens.

Thanks!
Welcome to ESD. Chances are, the humidity level where your computer is, has changed, so you are more likely to have static build up. Get into the habit of touching metal things around your computer (desk, chair, filing cabinet, a ground-lead, etc, before you touch your computer or keyboard. Put it on an ESD mat and ALWAYS touch that first.

I worked in an office place years ago like that, and simply got into the habit of grounding myself before I touch a computer or peripheral.
 

Lo_volt

Joined Apr 3, 2014
189
Do you have all of the covers on your PC? Are all screws in place? How about the screws to your graphics card and any other peripherals?

It's clear that you are the source of the static charge. The PC isn't moving, you are and when you remove your sandals, the charge does not build up.

Static issues like this are weird and tricky to diagnose. Try to follow the discharge current. It's not always obvious. Many posters have mentioned the power cord; make sure it's ground conductor is connected. Also check your video cable and your monitor ground. If your monitor is two wire and not grounded then the best you can do is make sure the shield on your video cable is good. You can try to move cables around inside the PC to see if that affects the issue. As I noted above, make sure everything is screwed down properly.
 
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