Electric Static Discharge

[haroldrock]

:)A few silly" first timer" questions. According to several "Build it yourself" books and tutorials ESD requirements are: grounded wrist strap, grounded floormats, rubbergloves and a wooden table to put the computer on. I have a hard polyethylene top table can I use this table without a cover? Furthermore I want to take my time in the building process how should I cover the unfinished machine overnight with a plastic bag or may be better with a large carton box upside down over it ? All these questions in connection with static. Thanks a million for helping me out. Regards Harold Rock

[rjfvillarosa]

Couple of simple questions, what is the weather like generally where you live?, what is your home constructed of?, and what is the floor material?

[Chris_Rootes_Wizard]

Well, an antistatic mat and wrist strap, yeah, it would be dumb to do it on a metal table, but if its wood, you could put cardboard down, then the antistatic mat, and the wrist strap connect to the antistatic mat. (the cardboard maily to protect the table :) )

"rubbergloves" Well, the writstrap, will do, no reall need for rubber glove too.

No need to repate the q's above :)

CW :)

[DarkPacMan77]

about a year ago i had an old hp pavillion that had an issue with the mobo... i believe that the monitor port was coming loose and that was what was causing bad picture/ discoloration etc.

back then, i was also computer-stupid (still am to very few aspects) and I ended up taking out almost the entire contents of the case, and I just rebuilt the computer on the carpet in my room which is right next to my feet moving back and forth and my chair w/ plastic wheels.

the computer did not recieve further damage, but also crapped out a month later due to the port failing.

I guess what I am trying to say... is that you need to take certain precautions, but do not worry if you are just a little sloppy. Wear a wrist band, and build on a good surface and you should be just fine.

[rarchimedes]

As long as you touch metal at every opportunity, you have few worries. Grounding is one of those things that can kill parts, but it is rare. In a manufacturing environment where parts are exposed and there is much mechanical movement by machines with various electromotive devices, I have seen the blowouts on photomicrographs, but those situations really do not apply to most home situations. If you have a static intensive carpet and a very dry situation, you do need to be a bit more careful, but some anti-static spray from your local parts store or even janitorial supply will handily solve the problem. Things like smoking and sprays of all varieties around running computers are the worst problem, because computers suck that stuff through and plate it out on the parts, producing a layer that insulates, trapping heat, and heat kills electronics. Running things too hot kills a lot more electronics than static ever did. The other place that is absolutely critical is powerline and phone/cable protection. Get a battery that also has over/undervolt protection, and run all connections to the computer from outside the house into these protection devices. I also have what is known as a gel-cell across the leads of my power box, diverting major lightning hits to house ground at the box. That means my machine protection does not take big hits. Do these things, and you won't have problems. Wrist straps are seldom properly used by amateurs, and don't have much effect in any case, because they themselves are seldom properly grounded.

[rjfvillarosa]

I also have what is known as a gel-cell across the leads of my power box, diverting major lightning hits to house ground at the box. That means my machine protection does not take big hits. .
Can you elaborate on this procedure ie: with instructions or diagrams if possible?

[haroldrock]

First of all many thanks for your fast replies. This is my first post and I want to do it right. Am I suppose to thank each of you individual with a seperate message or one message which contains all the names of the nice people who answered and helped me?a)ChrisRootes Wizard Thanks Chris for the explanation b) Dark Pac Man 77 Thanks for telling me your personal experience. c) rarchimedes Thanks for your very elaborate explanation. The last one is rifvillarosa who had a few questions for me .Here are the answers: The weather is excellent here.Mild winters and summers. The home is woodenframed with fibercement siding and tyveck. The whole house is carpet except the bathrooms and kitchen. I hope that I answered your questions properly Mr. Rifvillarosa. Kind regards and thanks again to you all Harold Rock

[rjfvillarosa]

The weather and house construction can give an indication as to whether you would be susceptible to static build up.
Here in the Caribbean the thunderstorms are very regular and quite hairy on occaisions, but as there is no chance of cold or rising damp the house is not built with any kind of damp proofing in the floors and so with the heat and me being barefoot most of the time I am constantly grounded, no worries about static.
If when you are building your machine you can install the power supply first and connect the power cable to the wall outlet, your case will be instantly earthed (grounded) this means everytime you touch the case to do anything you will discharge any static build up in you to the frame of the case and safely away to earth.
Good quality power supplies usually come with an on off switch on the back, just install the power supply first and keep the switch in the off position, this will stop power going to the power supply but still connect it straight to the earth circuit.

[Chris_Rootes_Wizard]

"ChrisRootes Wizard Thanks Chris for the explanation"

No problem mate, any time, also thanks for being so polite :)

[rarchimedes]

rjfvillarosa,

Here is a really good discussion of large scale lightning protection:

Power Protection discussion (http://yarchive.net/electr/lightning_protect.html)

The device I have used for years is a little less monstrous, but has kept the electronics in my house protected. It is the Delta Lightning Arrestor LA 302. You can look at it all at www.deltala.com. They want to sell you the LA 302-R and CA 302-R combination, which are $40 and $45 respectively, the "R" meaning residential, but I have the LA 302, which is in their commercial products. The difference is from 60,000 amps to 100,000 amps capacity. Both can stop almost unlimited strikes without damage. Here is a quick explanation of how surge arrestors work:

http://www.deltala.com/how.htm

Here is another good article on lightning protection:

http://www.windsun.com/Lightning_Protection.htm

The LA 302 or other units spoken of here should be installed in the breaker box, across both legs of the 220. There are diagrams on the site for almost any possible configuration. Here is a site that carries them cheaper than the home store:

http://store.altenergystore.com/FusesBreakersEtc/Lightning-Arrestors/c579/

Here is a description of the LA 302:

http://www.deltala.com/download/300vComm.pdf

Good luck.

[rjfvillarosa]

rarchimedes
I also have what is known as a gel-cell across the leads of my power box, diverting major lightning hits to house ground at the box. That means my machine protection does not take big hits. .
I have seen all things you list in that post before and the links provide some interesting reading, but, to me a "gel-cell" is a lead/acid accumulator that stores sacraficial energy that can be replenished with a charging unit, in other words a rechargeable battery normally used in motorcyles or boats, the reason it is called a gell cell is because the electrolytic medium is a nonspill gel rather than the distilled water used in normal automobile applications.
In all of those pages you list there is no mention of a gel-cell, plenty of electrolytic capacitors, I just don't see how a rechargeable car battery can assist you as a lightning protector.

[rarchimedes]

I believe that the silicon carbide crystals in the varistor phase change to a gel at a certain voltage and amperage, allowing enormous through current, and then revert to crystal form. That was the description that was given when I bought this thing some 18 years ago. I cannot find that on the site, but I bought the thing through a mag the first time. Gel-cell batteries were not common at the time. Since I have one sitting at my feet through which my machine's power is routed, I do know what they are. It is the rare term these days that does not have more than one possible referent. In any case, I hope that some readers will find the writeup useful, even if you did not. Whole house protection is getting to be an absolute necessity these days, with solid-state electronics in practically every device we attach to the power system these days.

[rjfvillarosa]

I hope that some readers will find the writeup useful, even if you did not. .
Please don't misunderstand me, I only wish I could get half my customers to accept and understand the VERY valid points in your links, (even if it does cost me money in lost repairs).
I just wanted to understand the inclusion of the "gel-cell" in your protection, as like I said, the only gell-cell I am aware of is a lead acid automotive battery.

[rarchimedes]

rjf,

No offense taken. I did, however remember one point that often gets lost in power discussions, and that is the difference between a simple battery backup and a voltage regulator. Some battery backups include voltage regulators, and some do not. You can imagine that most of the cheap ones do not. The 750VA I use includes one. In any case, much damage is done to systems by under/over volt situations, which they may not notice otherwise. When the airconditioner comes on in our house, we get a slight undervolt, which is reported by my unit with a flashing yellow light. Most such devices can correct any voltage from 85- 135 back to 110-115. Separate voltage regulators are rather expensive, but several of the better UPS's in the 650VA and up sizes include one for less than you could pay for one separately.

[DarkPacMan77]

storms are never so bad in michigan where i live that i would need such severe protection, but just a warning to all people that read this thread and get turned away by all of the large terms, just make sure that you take the proper precautions to your system for where you live because who knows, you may never need it, but if your climate changes often, you need to know how to protect your electronics. Simple home dehumidifiers help out too for humidity.

[glc]

Actually, humidity is not the problem - it's the LACK of it that causes static electricity. If you live in a colder climate you need a HUMIDIFIER in the winter months.