Avoiding Static electricty

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A friend of mine bought a new graphics card for his computer and he also
got a high end power supply , I told him to contact me when possible so
i can go to his place and install the new upgrades

I dont wanna end up messing it up he is low on budget so i would like to

whats the best way to discharge static electricty before opening the
case and working in it

Re: Avoiding Static electricty

PcGAmeR22;1341926 Wrote:
> A friend of mine bought a new graphics card for his computer and he also
> got a high end power supply , I told him to contact me when possible so
> i can go to his place and install the new upgrades

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> know

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> case and working in it

Use an ESD Wrist Strap such as-->

Or at the very least touch the case frame inside (unpainted metal) from
time to time while working with the PC.

Remember to avoid touching chips, contacts or pins when handling or
installing cpu, memory sticks, and expansion cards...always hold or
press from the edges.

Re: Avoiding Static electricty

rb wrote:
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The desired function, is to "bring all components to a common electrostatic
potential before assembly".

That means occasionally touching the chassis, doesn't count. Once you
remove your grasp from the chassis, now the items are "charging up again".


    tribocharging, electrostatic induction

Even electrolytic capacitors will do that, but for different reasons. If
you take a shorting strap and discharge an electrolytic, then release the
strap, the capacitor will still have residual charge. In fact, on the old
high voltage caps, there is still a significant shock hazard if you
do it that way.

So the purpose of the ESD wrist strap, is you connect it to the chassis,
and connect it to you. The wrist strap should have around a 1 megohm
resistor in series with it. The charge on you and the chassis equalize
slowly and the potential difference is zero.

While holding the ESD bag the video card came in, you touch and hold
the inside of the bag, while at the same time withdrawing the card
from the bag. Now, you hold the faceplate of the card (as it is grounded),
and try to continuously hold that while inserting the card. The chassis
and you are at a common potential because of the wrist strap, but the
video card would only be at the same potential, for as long as you're
touching the faceplate. You may need to switch hands while inserting
the card, to maintain continuous contact.

One reason for this degree of care, is some Nvidia motherboard chipsets
in the past, ended up with "blown out" PCI Express slots. Which suggests
the electrical signals in the slot on the motherboard, are overly sensitive
to static.

Using an ESD strap, plus using some care while inserting the video
card, should lead to a successful install. You can "simulate" the
common potential thing by cheating, but it's pretty hard to maintain
contact until the install is finished.

Devices vary, in their ability to resist ESD. I've worked with MOSFETs
in a transistor can (four legs), where there are no clamp diodes, and
the device has a 30V ESD rating. ICs can have 1001 volts, 2001 volts or higher
ratings. Those are relatively robust, compared to the 30 volt parts.
USB ports are around 5-6kV of ESD rating. The very best parts, are
RS232 chips with 15kV ESD rating on the modem data pin end. RS232
chips needed those ratings, because of the large numbers of RS232
chips blown out by static. I replaced a bunch while I was working,
on things like test equipment and even on the computers we built.
(MC1488, MC1489 chips). With the newer 15kV rating, doing replacements
like that is a thing of the past.

A human can build up a reasonable level of ESD charge, to the 50kV
level. That means if you're completely clueless, scuff across
the carpet and then touch the PCI Express slot on your motherboard,
it's going to be blown. Even the RS232 chips could be blown, if you
could get close enough to the pins while scuffing across the carpet.
A lot of connectors, due to the metal shell around the pins, that
provides "direct contact protection", where the discharge would
have gone right into the pin. But ESD can also do damage by induction,
which is how a lot of stuff in your house gets damaged in a
lightning storm. A conductor could be hit 100 feet from you,
and just the induced voltage in conductors within the house,
will destroy stuff. The same is true of ESD discharge on connectors,
in that, the charge may dissipate into the chassis, but not before
being induced into adjacent conductors.

This is one of the proposed failure mechanisms on ICH5. A user discharges
ESD into the metal shell of the front panel USB connector. But because
the metal shell doesn't have a good connection to metal in the chassis
(the front panel is typically made of plastic), the discharge into ground
goes down the ground wire in the USB front panel cable. But at the
same time, the ESD is induced into the adjacent D+ and D- signals,
leading to latchup failure at the ICH5. So in the computer, one of
the worst designs from an ESD defense point of view, is front
panel connectors. By seating the connectors in plastic, that's asking for
induction based failures. And is why I recommend making connections
to a PC, via the rear connectors. As everything back there has a
metal connection to the chassis. That's why the rear I/O plate
has those "springy fingers". It helps with ESD. The springy fingers
shorten the distance an ESD charge has to travel, to get to the chassis


Re: Avoiding Static electricty

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I keep part of my arm on the chassis at all times.


Re: Avoiding Static electricty

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That's fine if the chasis is earthed!

Re: Avoiding Static electricty

On 27/05/12 08:20, GT wrote:
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Technically it doesn't matter. so long s chassis, your bodt, the card
packaging and the card are at the same voltage, then there will be no
discharge. Hint, how they work on live high voltage lines.

Re: Avoiding Static electricty

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Leave the PC plugged in and turn off the socket at the wall to cut the
power - the whole case is then earthed and anything touching the case is
also earther. No need for anti-static straps, wrist things or anything

Re: Avoiding Static electricty

On Saturday, May 26, 2012 3:20:26 PM UTC-7, GT wrote:
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Wrong.  Really wrong and potentially dangerous.  

You shouldn't leave the AC cord plugged in because a direct, low impedance =
connection between you and earth ground can be dangerous, as evidenced by p=
eople touching defective toasters and faucets at the same time.  That's why=
 anti-static wrist straps have a million ohms between them and their ground=
 clips.  Some electronic assembly factories make workers go through a check=
point where they have to plug in their wrist straps, and any that measure m=
ore than about 2 megaohms or less than 1 megaohm are rejected.

It doesn't matter if the computer chassis is at earth ground or 20,000 volt=
s higher.  The only thing that matters is for everything to be at the same =
voltage, and your recommendation won't eliminate the need to take anti-stat=
ic precautions.  

Re: Avoiding Static electricty

larrymoencurly@my-deja.com wrote:
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Earthing is irrelevant, and adds nothing to the problem of ESD.

"everything to be at the same voltage" a.k.a. equipotential, is exactly what's

When three items being assembled, are all brought to the same potential before
touching one another, there is no delta_V and no net current flow when
they touch. Using the 1 megohm resistor (or the high resistance per square of
an ESD bag), is so any discharge actions required, have a relatively long RC time
constant, causing low peak current flow. Current density is part of the damage
phenomenon. Using the 1 megohm resistor, results in the eventual equipotential
condition, and while things are getting there, the current flow is tiny, and
won't "blow a hole" in any semiconductor junctions.

"Earth" is simply another reference point. Sure, you can earth yourself and
earth the chassis, and earth the ESD bag. And by doing so, you're equipotential
(so no net current flow when the items touch). But you can just as easily
"be your own electrical island", and as long as the three items are connected
by the equivalent of an ESD strap (conductor with moderate resistance), you
won't need earth at all. You don't need to "drain" stuff, as much as you need
"all items charged to the same voltage". It doesn't matter what that
voltage happens to be, relative to any other items not within reach in the
room. If there was a Wimhurst machine across the room, charged to 1 million
volts, since you're not going near it, that voltage is irrelevant. Just
as irrelevant as earth would be.


Re: Avoiding Static electricty

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The one advantage that "earth" has is that within a particular building,
if it's properly wired, it's roughly equivalent.

This means that if I touch my desk, computer case, storage shelf, etc,
they all have the same reference voltage.

While it's true that I can be my own "electrical island", as soon as I
bump a metal part of my desk I'll be grounded back to earth, while the
components on the non-grounded part of my desk will be in their own
electrical island.

I prefer to ground my desk and keep everything as close to earth's
voltage level just to increase the size of my electrical island.

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