ESD Issue? Kind of long

I'm trying to understand why ESD ( if indeed that’s what it is) on the external portion of computer case fried my motherboard on two different occasions over a 4 month period.

In each event, I was reaching to push the eject button on my DVD drive. When I pushed the “Eject” button on the front of the DVD Optical Drive I felt what I perceived to be a static spark. The ESD caused the computer to power off and in each of the two occasions; the motherboard underwent a catastrophic failure.

Had I been inside the case when this occurred, well, this would be a no-brainer as they say.

The only time I've heard of ESD on the external portion of the case causing a catastrophic failure was when the computer was not properly grounded.

After each of the two ESD events, I checked to ensure that my 3-prong outlet was properly grounded. The computer is connected to a Belkin 1100VA UPS which connects to 3-prong receptacle. The earth ground was checked with an inexpensive outlet tester (the kind that shows “open Ground”/Open Neutral/Open Hot/Hot/Grd Reverse/Hot/Neu Reverse/Correct) and a digital multimeter. All indications were that a good ground existed.

After each event I’ve even had an electrician come to my house and check the wiring/receptacle for proper installation/ground.

The mobo was inspected and the stand-offs were all verified to be in correct (none where they did not belong). The mobo was not making improper contact with the case as best as I could tell.

The power supply (a new PC Power & Cooling 610) was tested and found to be in good working order (using the test procedures provided by the manufacturer)

The computer (3-prong cord) was plugged into a UPS (no indication of a Site Wiring Fault) and the UPS is plugged into a grounded 3-prong receptacle.

It's possible but it just does not seem credible that the spark would have to jump from your finger through the non-conductive plastic of the button and enter a live circuit without encountering any grounded part of the drive's chassis or computer case first.

For the DVD Drive, the electrical grounding is handled through the power cable grounds. By removing the Bezel on the front of the DVD Drive it looks like the switch is supported by a metal bracket that is soldered to the circuit board. On the front surface of the switch there is a small metal shield with an opening just large enough for the activator button to protrude through. On the chance that a static charge winds its way around the outer button through the bezel it will be picked up by this shield and routed to the DVD's circuit ground and then to the DVD case.

I did, after the second ESD event, find a bare exposed wire on the Ribbon cable (pin 39, LED indicator) that connects to the DVD and to the Mobo that was most likely touching the metal case of the DVD drive. I was thinking at first that this bare ribbon cable wire touching on the metal DVD case might be the culprit.

However, a couple of PE-EEs that have reviewed these two events don't think that the Ribbon Cable is a contributor to the ESD causing a catastrophic failure of the mobo (twice). They just don't feel that even a short in that ribbon cable could lead to ESD given the low voltages in those conductors.

I've replaced the power supply, DVD Drive (& the obviously bad ribbon cable), case fans and taped over all unused Molex connectors.

I've placed an electrically conductive mat in front of my desk and computer with grounding straps to the grounded receptacle and a second grounding cord that has a wrist strap that is on top of my desk that I can touch before touching my computer.

The conclusion by the professionals that have reviewed my situation is that they feel that this occurred because something is just not properly grounded. I believe them too, but I just can't find anything other than the bad ribbon cable that seems to be out of order. I would like to know the culprit if it’s knowable 

I did read about another person who recently had the same problem when he touched the eject button on this DVD Drive which caused he computer to power off. However, he was able to reboot and all seems to be fine for now (he might have some unknown latent issues though). He could not find a grounding issue either.

I trust and believe the professionals that have provided their opinions on this issue. However, I just can’t seem to find convincing proof as to the cause. I’m most likely beating a dead horse in the ground (no pun intended ) but I have always been a big believer in Peer Reviews as a good method for reviewing problems/solutions.

Has anyone else seen/heard of this type event?

Could it have been the DVD Drive (It showed to be grounded when testing with multimeter?

Could it have been the ESD coupled with the Ribbon Cable hitting the metal DVD Drive? Can I rule out this cable as being related to the problem or not?
(see snippet below). The grey colored portion below the ribbon is the top of the DVD Drive. When I checked if the exposed wire could contact the metal DVD drive, I saw that because of other power cable near by, the ribbon cable was pushed up and folded up on top of the DVD Drive and the exposed wire easily made contact to the metal case of the DVD drive.

Could it be something in the construction of my case? (Tests don’t indicate grounding issues.

Could I have just plugged a cable in incorrectly on both occasions that fried the mobo?

**broken link removed**

I’m even going to replace my case just out of fear/ignorance

Something was not grounded, but what?

At this point it may be to all speculation, but II would appreciate any further comments/thoughts on this situation. I'm just not convinced I've found a solution to my problem.

p.s., I do admit to being very anal retentive

Thank you

Disconnect all cables from the DVD drive. The DVD case should still be grounded to the computer case. If not, find out why.

mneary said:

Disconnect all cables from the DVD drive. The DVD case should still be grounded to the computer case. If not, find out why.

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mneary...Thanks for the interesting suggestion. I'll give that a go.

However, it's my understanding (perhaps wrongly) for the DVD Drive, the electrical grounding is handled through the power cable grounds and not metal to metal with the DVD Case and PC chassis. Agree/disagree?

The DVD should be bolted directly to the PC frame. Mine are.

mneary said:

The DVD should be bolted directly to the PC frame. Mine are.

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On my older case they were connected like yours, however, when I asked a manufacturer of Optical Drives about the newer plastic sliders used today on most peripheral drives I was told that years ago every internal drive featured a grounding tab that could be connected to the computer's metal case, but nobody ever grounded them. So these days the electrical grounding is handled through the power cable grounds.

In my new Antec P180 case, which is designed for quiet operation, the drives are mounted in a cage with huge silicone rubber washers that completely isolate the drives from mechanical contact with the case.

Like you, I'm of the opinion that it would be a good practice to make sure the DVD drives are grounded to the chassis of the PC case.

I'm not really sure my problem is ESD but perhaps another source.

Thanks for you comments

Maybe nobody ever grounded them, but I do. Although the risk of ESD is usually low here (a beach city), it's just too cheap to do.

The power ground is not an acceptable ground for ESD.

Where are you located? What's your indoor humidity? Here it's 75%, so I'm not worried today.

mneary said:

Maybe nobody ever grounded them, but I do. Although the risk of ESD is usually low here (a beach city), it's just too cheap to do.

The power ground is not an acceptable ground for ESD.

Where are you located? What's your indoor humidity? Here it's 75%, so I'm not worried today.

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I'm located in the very north end of the Texas Panhanle and it is a dry climate, especially in the winter. Right before my last mobo failure in March, our dewpoint had been as low as -16. Our RH often runs 10-15%.

Also, in concurrence with your thoughts, a couple of EE's have stated that if the static charge managed to get to the DVD circuitry it should have burned out the DVD and not my motherboard. This further suggests that the DVD was not properly grounded and the charge managed to travel through the DVD interface cable into the motherboard. Insuring that the DVD is grounded will be a big help.

What you said about the power ground not being an acceptable ground for ESD sounds very interesting...can you explain a bit more for my education?

The system power ground is part of a closed loop for power regulation it's not meant to be a target for current spikes to discharge through, that's what the 'safety ground' is for. ESD's are going to go through the path of least resistance, if your Earth safety ground is good and your case is grounded you have an exceptionally low resistance to that ground so a voltage spike is going to want to go that way instead of through the PC, basically creating a giant voltage divider preventing high voltage from reaching anything in the PC.

Sceadwian said:

The system power ground is part of a closed loop for power regulation it's not meant to be a target for current spikes to discharge through, that's what the 'safety ground' is for. ESD's are going to go through the path of least resistance, if your Earth safety ground is good and your case is grounded you have an exceptionally low resistance to that ground so a voltage spike is going to want to go that way instead of through the PC, basically creating a giant voltage divider preventing high voltage from reaching anything in the PC.

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Sceadwian...thanks for that excellent explanation. What you say is starting to sink in (slowly tho )

Do you think then that the Ribbon Cable hitting the metal DVD Drive had any part to play in my mobo issues? Or can I remove it from the equation?

For the DVD Drive, the electrical grounding is handled through the power cable grounds. By removing the Bezel on the front of the DVD Drive it looks like the switch is supported by a metal bracket that is soldered to the circuit board. On the front surface of the switch there is a small metal shield with an opening just large enough for the activator button to protrude through. On the chance that a static charge winds its way around the outer button through the bezel it will be picked up by this shield and routed to the DVD's circuit ground and then to the DVD case.

Click to expand...

That nick in the ribbon cable looks like just that, a nick in the cable. Sure that's a possible entry point for an ESD, but only if it was near something that had a high voltage. You really need to test the DVD drive's case and it's power ground and see if they're connected. If the metal case to the suspect DVD drive connects to it's main ground I'd rule the DVD drive out and look for a bad local ground instead. Though if that nick in the ribbon cable was right against the DVD case at the time, who knows.. An ESD failure is VERY difficult to track, especially considering it could have simply been a bad cap in the motherboard, or the DVD drive itself, or who knows what else. You can stack up a series of culprits very quickling in cases like this, but you can never outright prove anything.

Sceadwian said:

That nick in the ribbon cable looks like just that, a nick in the cable. Sure that's a possible entry point for an ESD, but only if it was near something that had a high voltage. You really need to test the DVD drive's case and it's power ground and see if they're connected. If the metal case to the suspect DVD drive connects to it's main ground I'd rule the DVD drive out and look for a bad local ground instead. Though if that nick in the ribbon cable was right against the DVD case at the time, who knows.. An ESD failure is VERY difficult to track, especially considering it could have simply been a bad cap in the motherboard, or the DVD drive itself, or who knows what else. You can stack up a series of culprits very quickling in cases like this, but you can never outright prove anything.

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Sceadwian & mneary...Thank you and for the excellent and generous comments. I'll do as you suggest and test the DVD drive's case and it's power ground and see if they're connected.

Thank you!

The metal case to the suspect DVD drive shows to be connected to it's main ground.

Another EE that reviewed my issue stated that he felt the DVD drive is the most likely culprit but that he also was not convinced that the PSU isn't at fault. Particularly if it's an intermittent problem, the PSU could seem fine when tested, but still exhibit unusual behavior at other times.

I contacted PC Power & Cooling today, and they agreed to RMA the PSU in case there is an intermittent problem.

However, based on the comments here I'm going to ensure the DVD Drive case is well grounded to the PC case chassis based on Sceadwian's comment:

The system power ground is part of a closed loop for power regulation it's not meant to be a target for current spikes to discharge through...

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It's not easy being paranoid and anal retentive at the same time

Peach, one thing you don't really mention is how the computer behaved after the ESD incident. Did it turn on at all? Did it give any error messages, and if so, what were they? Any lights on the case, keyboard, etc on boot? POST beeps? Fans running? etc.
If ESD is really the culprit this is a case of bad design on the part of the Case or DVD drive manufacturer. It reminds me of a case with a very expensive IFR 2975 test set where the manufacturer told us that it needed a plastic coated antenna because a metal one would allow static charges to kill this $40K device!!! What a crock of BS... Bad design, just like your PC. I would look at making some noise and getting a different one at no charge from the people you bought it from. It can't hurt to whine.

kchriste said:

Peach, one thing you don't really mention is how the computer behaved after the ESD incident. Did it turn on at all? Did it give any error messages, and if so, what were they? Any lights on the case, keyboard, etc on boot? POST beeps? Fans running? etc.

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When I felt and heard what I perceived to be ESD (when I pushed the eject button on the DVD Optical Drive), the PC powered off and did not restart at all. At first I thought it might just be a digital fault that could be relieved by turning off the power switch on the PSU, unplugging/reconnecting the power cord and power the system backup.

However, when I would turn on the power switch on the PSU it would power on for 3-4 seconds and shut down. I thought at first it might be a stuck power switch but that wasn't the case.

I did the normal troubleshooting routine of setting up the motherboard and minimum components outside of the case but it would not power on. I switched out various components including a different PSU, Graphics Card, etc., but that did not help. After a bit it seemed obvious it was the mobo.

As soon as I replaced the mobo, it powered backup just fine.

That was it...except about 3 months after the first fried mobo, the exact same thing happened when I reached to push the eject button on the DVD Optical Drive. Again, the system would power on for 3-4 seconds and then power off.

If ESD is really the culprit this is a case of bad design on the part of the Case or DVD drive manufacturer

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Do you think the PSU could possibly be the problem?

Thanks for your comments

Just because the DVD drive was the entry point for the ESD doesn't mean it was at fault, you're after all going to hit that one button more than almost any other on your system if you use your DVD drive a lot. Since you've said that the DVD's case is connected to it's power ground either the ohmic connection between power ground and case ground is weak, or the local ground itself is faulty (not being of sufficiently low impedance during an ESD to sacrificially draw the current away) The kind of failure you're talking about is virtually impossible to trace if everything is grounded. Because you need to determine the individual components impedance to the power ground during a massive voltage/current pulse, IE under loads which aren't practicle to test at with home made equipment.

It's a needle in a haystack, and the haystack is made up of needles.

Sceadwian said:

Just because the DVD drive was the entry point for the ESD doesn't mean it was at fault, you're after all going to hit that one button more than almost any other on your system if you use your DVD drive a lot. Since you've said that the DVD's case is connected to it's power ground either the ohmic connection between power ground and case ground is weak, or the local ground itself is faulty (not being of sufficiently low impedance during an ESD to sacrificially draw the current away) The kind of failure you're talking about is virtually impossible to trace if everything is grounded. Because you need to determine the individual components impedance to the power ground during a massive voltage/current pulse, IE under loads which aren't practicle to test at with home made equipment.

It's a needle in a haystack, and the haystack is made up of needles.

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Sceadwian...Thanks for your informative comments. I certainly agree with your analogy using the haystack made up of needles. That seems very appropriate to me

I do agree with your comment:

Just because the DVD drive was the entry point for the ESD doesn't mean it was at fault...

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Notwithstanding your comment, I did learn a bit more about the plastic drive mounting brackets on my case. I have some metal mounting brackets that came with an older case but they do not fit on my Antec Solo case that came with the plastic mounting brackets (Sliders). The metal brackets are wider and it would be difficult to mod them to fit. Below you can see how one of the plastic sliders fits in my case. It slides between the cutouts (donuts). The metal sliders are too wide to fit.

However, while reviewing other cases yesterday I noticed that the Silverstone TJ-09 (which I might purchase) does not use the plastic mounting brackets. I'll have to confirm this for sure, but it looks as though the peripheral drives mount flush (metal to metal) with the metal cage. Based on the comments I've received, this seems to be a good practice for ensuring a good safety ground.

A comment posted on another site has made me change my mind about using conductive copper tape to improve the ground of the DVD Drive:

Esd protection is more involved than adding a ground strap to the DVD. The problem with esd is that it generates a very rapid change in current (di/dt) which creates a rapidly changing "B" field which in turn causes a voltage change. In addition, the "B" field induces voltages in other conductors. The dvd should be mounted in the metal chassis enclosures with a good ground on both side of the dvd to the chassis.

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**broken link removed**

Thank you for your comments

Ahh, sorry about that, I wasn't paying close enough attention to the plastic mounting brackets comment. Every drive of any kind I have ever used has metal to metal contact between the device case and system case, I was just mentally assuming this existed, the picture helps a lot. I wish more people used images. I've never seen plastic mounting brackets like that before, and I'd immediately throw them out the window if I did =)

Sceadwian said:

Ahh, sorry about that, I wasn't paying close enough attention to the plastic mounting brackets comment. Every drive of any kind I have ever used has metal to metal contact between the device case and system case, I was just mentally assuming this existed, the picture helps a lot. I wish more people used images. I've never seen plastic mounting brackets like that before, and I'd immediately throw them out the window if I did =)

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Sceadwian...I did confirm from owners of the Silverstone TJ09 that the drives attach metal to metal using screws. I plan to order this new case next week.

BTW, I have sent Antec an Email asking about the use of the Plastic Mounting Brackets and relating my failed mobo experience. I'm just curious to see what they say. I noticed that even their most expensive case uses these. The only reason I can think of why they would use the plastic brackets is for quieter operation. A solid safety ground would seem more important.

Thanks again for your very informative comments and help.

Good luck with your future system, you could also create a grounding point on the outside of your case to touch before you touch any other part of the system. Most cases are painted or otherwise insulated from the chasis material itself, but you could put in some kind of direct metal contact to the chasis that you just get into the habbit of touching before you do anything with the computer, or otherwise make the immediate environement less prone to static build up (conductive mat or more grounding points)

Sceadwian said:

Good luck with your future system, and if you don't want to worry about this problem too much in the future and your environment is really that bad for static create for yourself some easily touchable point on your desk and connect it via high gauge wire to the case somewhere, it wouldn't take much effort to make a very unobtrusive grounding point that you could train yourself to grab onto firmly before touching the PC. Or figure out how to otherwise safely ground the immediate environment near the computer.

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Great advice! Will this work?

I currently have a 3M Velostat electrically conductive mat (4'x6') in front of my desk and PC. The mat is connected (via a cord) to the metal screw on my grounded 3-prong receptacal. The mat also has attached to it a snap-on cord with a wrist strap that I have attached to the top of my desk that I touch before touching my PC. I also use this grounded wrist strap when inside my PC.
**broken link removed**

Whew!...now for my Conductive Safety Shoes