Static arc to case killed processor(?)

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Re:Static arc to case killed processor(?)

by jconner Mar 22, 2004 1:40AM PST

Without a CPU, how did you run diagnostics? That would also say the memory is OK. Perhaps its something else that got whacked such as the boot sector or other magnetically recorded media? Probably need a little clearer idea of how you decided the processor is dead. Black screen could be no power at all. Sure it wasn't a blue screen?

You can place the computer on an anti-static surface / pad. Don't place the case on carpet. You should have ground through the outlet / powerstrip or a surge protector. If home built perhaps the motherboard is not isolated from the case using the washers that are made for this.

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Re:Re:Static arc to case killed processor(?)

by mshirley001 Mar 22, 2004 1:50AM PST

I have never heard of such a thing ever happening unless, like you said, the case was opened and you were poking around inside.

Do you have any power at all? ps fan spinning, lights anywhere?

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Re:Re:Static arc to case killed processor(?)

by cyndekay Mar 22, 2004 1:56AM PST

<<Without a CPU, how did you run diagnostics?>>
Should have been more clear - didn't run diagnostics, used diagnostic section of the manual. Manual had a diagram of 4 lights at the back of the machine. It said if the 4 lights were red, the processor is dead or damaged. The 4 lights were red. My shiny new (January 21, '04) 64-bit Athlon processor is fried.

Power is not the problem - I can still open and close the DVD drives, the monitor comes on, but with a black screen and blinking green stand-by light. The fans come on as well. It was plugged into a good surge protector, but that was apparently not enough.

Its a CompUSA machine, we bought a different power supply at purchase, and they were to install it. When we came to pick up our machine, I had the strong feeling they were scrambling through the installation while we waited. Perhaps the power supply was improperly installed (i.e., not properly grounded).

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Re:Re:Re:Static arc to case killed processor(?)

by mshirley001 Mar 22, 2004 2:02AM PST

That sux. Do as was said and make sure that no part of the backside of the motherboard is making contact with the case, if not... Warranty?

you might also try unplugging it for awhile... Im no expert or anything, just trying to help.

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Again, the mounting holes SHOULD be connected to the mounting plate!!!!!!

by Ray Harinec Mar 23, 2004 4:44AM PST

BUT, nothing else should touch. Happens a lot when one changes to a different mobo type and leaves a hex standoff at a place other than a mounting hole.

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Lack ofPower Supply ground makes a lot of sense, However

by Ray Harinec Mar 23, 2004 4:48AM PST

They would have to intentionall do something with specific intent to break the third wire ground inside of the power supply. I am assuming the plug/socket has the third contact.

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The mobo IS SUPPOSED to be grounded to the mounting

by Ray Harinec Mar 23, 2004 4:30AM PST

plate. You are totally misunderstanding the purpose of the insulating Washersa. They are for the sole purpose od preventing the screwheads of the mounting screws from ruining the printed circuitry around the mounting holes. Each of these holes are plated through holes and contact the inner ground plane of the mobo [a mobo has four layers, some new ones have six]. This plane is connected to the mounting plate via the intimate contact between the bottom side of the Mobo mounting holes and the Hex standoffs which contact the mounting plate. ALL of the mounting holes with plating around them are tied to each other in the MOBO.

The monting screws do not carry the ground currents, they simply apply the constant pressure needed to insure a good quality low RF noise contact between the grounding rings and the mounting plate.

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Re:The mobo IS SUPPOSED to be grounded to the mounting

by jconner Mar 23, 2004 7:04AM PST

Not totally misunderstood. The washers also prevent adjacent traces on the mobo or other components from being grounded, especially older motherboards and on those where the washer is underneath. On newer boards there is a specific ground through the motherboard and a nice ring around the screw holes which provides that.

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Putting the washers on the underside

by Ray Harinec Mar 23, 2004 7:39AM PST

of the mobo is probably the most ridiculous and ludicrous thing ever done with the washers. If there were six or eight mounting holes it was the most outlandish waste of time [and incorrect] thing that could be done.

HOWEVER, I have a book by Bigelow {PC Desk Reference] that said to do that. Fortunately I worked in Systems Engineering with the people that design these boards and was involved with all aspects of the grounding techniques to use for high frequency grounding techniques and EMI control [the noise on the DC voltage lines in computers is very high frequency, that noise is what is intended to be controlled/reduced]. Mr. Bigelow is simply incorrect.

We actually had a 14 layer board in the Minuteman system. [not a mobo, just a circuit board.]

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Re:Static arc to case killed processor(?)

by Willy Mar 22, 2004 2:01AM PST

Electricity, in whatever form does "mysterious" things. Basically, since you saw the "blue arc" that was roughly 40-50k volts jumping around. You have seen the after effects, so it does make sense to lessen its build-up. Use "fabric softner" (50/50 softener/water)or made for sprays around the carpet and mats. Ground the keybd. and/or add a static pad to touch before using anything. Check your home heating/cooling to increase humidity levels to proper acceptance.

As for correcting the system, you may have damaged not the cpu but other componets of the mtrbd. which will hamper the system booting. In either way, the damage is hard to pinpoint as it can be anything. Thus, either have a good tech look at it or bite the bullet and start lookng for a new system. If you have warranty, use it, but no mention of static damage.

good luck -----Willy

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Re: This a warranty issue.

by Stan Chambers Mar 22, 2004 10:01AM PST

A static discharge to the case should not cause this problem. The hardware is obviously not installed correctly. There shouldn't be any metal screws on the front of the case, but even so, it shouldn't cause this problem, unless something, the MB, is not installed properly. I use the case to discharge static electricity all the time, without any problems. Take it back.

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If your home wiring is reasonably modern, the third wire on

by Ray Harinec Mar 23, 2004 4:37AM PST

the AC Power connector goes directly to the Ground bus in your main power box. Thus your case is always grounded as long as the power supply is plugged into the AC Power.

Very difficult to understand how the CPU could get zapped. Could see the radiated spike from the discharge causing a glitch on the software processing. Very unlikely to cause damage, unless the computer is totally assembled improperly.

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Let's be certain that we understand the use

by Ray Harinec Mar 23, 2004 4:59AM PST

of an anti-static pad.

The pad has a resistor approx one megohm or greater. to ground. The pads function is to lessen the current flow that takes place during the discharge. [in effect, it spreads it out over time [tens of nanoseconds].

Now consider that a properly assembled and grounded system has a very low resistance to the ground bus in your main electric box [a couple of ohms]. In this case you have the megohms of the static pad in parallel with less than an ohm. The discharge will be high current through the low resistance path.

The purpose of the pad is that one should touch it first [and often, since simply moving stocking feet or leather soles, petting a cat et al can build up the charge rapidly]. By touching the pad, the discharge is so miniscule/unnoticeablethat you will have no idea that your body had a static charge.

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