Weekly Subject 02 - Safety and Computers

I have to agree about good safety habits, of course, in my profession bad safety habits can get you, or someone else, dead pretty quickly. Nonetheless, mistakes happen, God knows I've had a shock or two. Like the time when we were ripping out an old installation, we thought we'd killed everything, we spent hours testing that every circuit was dead - except for the one circuit running through the middle of a bunch of a few hundred others that was fed from a different distribution board - I'll give you 3 guesses who cut through that cable and got 240 volts!
The thing with RCD's / GFI's is that they allow you to make mistakes and get away with it. The danger then is that people can get careless and start assuming that they'll never get a shock - so, as you say, SAFE PRACTICES!!!
The second thing that was drummed into us at college was the 6 rules of safe isolation: Switch off, Lock off, Display notice, Test meter, Test circuit, Test meter again (you test the meter twice to ensure that it hasn't failed when testing the circuit). The realities of life in my profession mean that we work on live circuits more often than not. To the rest of you, I ask that you commit those rules to memory if you're going to work on electrical circuits (Obviously displaying notices doesn't apply in the home, really). Locking off: circuit breakers over here will allow a small padlock to be put in them to prevent them being turned on. If you have fuses rather than circuit breakers, then remove the fuse and keep it in your pocket - that way no one can plug it back in while you're on the other end of the cable.
Oh, and NEVER use one of those idiotic neon "mains testers" - the only thing keeping you from mains voltage is a tiny electronic resistor - I've heard of someone being killed after using one which had got wet. Fluke make an excellent inductive tester called a "VoltAlert" - that's safe, I have one in my tool box.

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Nick.

Well...that'll do it for me. I ain't going back into my PC case or touch the house wiring for nuttin'....uh-uh...no way.... https://discussions.virtualdr.com/

I have been hit a couple time with 277V , 308V and don't like it at all.

Yes, cheap [read marginal equipment] can get one into trouble.

bistro https://discussions.virtualdr.com/ https://discussions.virtualdr.com/ you are probably in there right now https://discussions.virtualdr.com/

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https://discussions.virtualdr.com/ OK...you got me. Was just in there changing out a RAM stick....with my radiation suit and it's 50 ft. grounding wire attached to a cold water pipe in the basement....and heavy rubber gloves....with the weather channel on full blast....forgot to evacuate the neighborhood first though. https://discussions.virtualdr.com/



[This message has been edited by bistro (edited 06-03-2001).]

Tut tut tut new you forgot something. like normal https://discussions.virtualdr.com/

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Interesting weekend. Stack overflow problem yesterday and two U S Marine reruiters in my home all afternoon for my youngest son. And to top it all off before I really wake up this morning I find myself talking about Zone Alarm on an inoculate thread on the 98 thread.

There has been a good job done so far on safety both for our bodies as well as the computers we own. Learning about power and safety issues of other countries has been nice.

Now let's shift the safety issue to tools and test equipment that you would work with on computers. Also we have touched on the work area needed a little bit. We have to realize that many people reading these threads for the first time have not used tools. Therefore to start this question will be asked.

What is the best work area to have in terms of safety?



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The 'Clean Room' at Intel. But if that's not available, the kitchen table (wood) will do. Just make sure you clear off that bowl of spaghetti first...I would not recommend a garage workshop; too dusty and you'd really wouldn't want that pipe wrench hanging on the peg board above to accidentally fall on top of a new motherboard you are installing.
As long as you have plenty of space and relatively dust free. No carpeting!

In the line of tools, all I have needed is a screwdriver. To remove the case cover.

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I have a sister who is a nurse and was able to "creatively acquire" a couple pairs of hemostats. They are great for working in tight areas like in the micro-towers. Even small pliers can crush things, but the hemostats, since they are designed for use with human tissue, are less likely to cause damage. They don't get used often, but come in handy for when the fingers are just too fat...LOL https://discussions.virtualdr.com/

http://www.library.spt.tec.sc.us/sur.../hemostatA.jpg

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I want my Win98 Emachine back !!!

MAXXIMILIAN'S

I once bought a nice little bag of comp tools in Germany for around $ 20-30. It contains everything I could ever dream of attacking a computer with (don't ask me to find and translate the names of the parts!). About half of it has never been used yet.

I wouldn't go as far as Train only using a screwdriver, but you really don't need much else (my little Leatherman multitool handles most). But it sure feels nice pulling out this little nifty toolbag when making "house-calls" at friends who called the "PC-doctor".

As to where to work I'd say find a wooden table where you can sit in a comfortable working position. You can get pretty sore in your knees working the beast on the floor if it takes more than five minutes. Besides, I have a perspiration "problem" (should be rather healthy to sweat a lot, they say...) and tend to start dripping once I really dig in, and sitting upright prevents sweat from falling onto the electronics, as it otherwise would if I was bent over the PC. And trying to find all these small screws again on the floor isn't much fun either...

Good working light is important also. I bought one of these rubbercoated flashlights and it's served me well. Since it's coated I can lay it somewhere inside the machine to have both hands free - one of my best "tools.

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Karl, Denmark
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"..and may The Force be with you too..."

[This message has been edited by kallikru (edited 06-03-2001).]

That flashlight sounds like a good addition. But, must admit a cross tip screw driver is all I have had to use, so far. It is a non-magnetic one.

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Speaking of flashlights...I buy those little packs of keychain flashlights; the kind you squeeze on and off. Hold it in my mouth and just bite down when I need the light. Just take off the little chain first...it can really zing your fillings.( https://discussions.virtualdr.com/)
Found those computer kits to be really handy. Non-magnetic, non-conductive tools.

In opening a computer case then, I may need to use a phillips screwdriver or a blade screwdriver. How do I determine which size to use?

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Trial and error mostly just make sure that it matches [fits] snuggley all the way around.
If it is loose it will tend to slip and thus strip it and that will cause more problems,

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If you go into the case often, would recommend metal or plastic knurled screws such as HERE. Makes it faster and easier to get the panel(s) off.

Bistro
Very true, forgot about them https://discussions.virtualdr.com/

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hmm...safety for the computers is good and all...but I say it is a question of philosophy...
I don't fear death or pain...the way I figure it, we all take a beating every once in awhile...
I've been electrocuted before...nothing big...
as long as I don't kill the PC its cool by me...I've worked on a live switch before too...

try this...(I'm sure some of you will) stick a 9-volt battery into your mouth...

did it hurt? at first it does, but then you get numb and you can't feel it...

you might say I'm stupid or have no common sense...but I won't die this way...I've worked on a PC still plugged in that my stupid colleague spilled water on...
now, I didn't know it was plugged in, and boy I got a shock...but she was at fault for not unplugging it and for spilling the water..she was reprimanded and I was fine...

don't be afraid of the light...safety is a good thing...but for anyone who lives like me, don't fear death...
I'm sure I'll get flamed for this post...but thats ok...I don't worry myself over petty details...


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Mark
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Good Morning All, zam1el, Thanks for posting and that is an interesting philosophy, but not one as you pointed out that most people would subscribe to. There is enough that happens to a person in a lifetime that causes pain. Why volunteer for it?

Now, once inside a case and for example we have an idea the power supply is bad. How would you approach checking the power supply and what safety precautions should be taken?

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As an Electronic engineer specializing in embedded computer applications I thought I would post to clear up a common misconception concerning the use of ground straps.

Computer circuitry is extremely susceptible to damage from static electricity. Anti-static procedures should always be followed when handling them. Just touching the chassis to discharge static potential is not enough to protect the delicate circuitry. An electronic circuit can have static damage and still appear to operate normally. It will have a higher MTBF rate and in many cases reduced performance. Commercial wrist ground straps, ankle straps, mats, etc. are designed for safety. They have built in current limiting resistance (on the order of multiple mega-ohms) to keep the operator safe from dangerous discharges containing high amperages. If used properly, like any tool, they are safe. Be sure to read and understand the instructions and safety precautions for the tools you use.

Electricity is extremely dangerous. It only takes 100uA to kill a human being. If you aren't sure you can perform a repair involving electricity properly and safely then don't do it. Leave it to the pros and don't risk your life.

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Once, during Prohibition, I was forced to live for days on nothing but food and water. - W.C. Fields

As with everything in life there's of course a certain risk involved when you stick your head in to a computer. Changing a lightbulb can under circumstances kill you, but that doesn't mean you call an electrician to do it for you, not..? You can cut off a toe mowing your grass (or even a foot) if you fool around while doing it. But that still doesn't keep people from mowing their grass themselves...

The meaning of this thread (and the following) is to give people an understanding of what they're up against, how they should go about it, what they should look out for ect. It's then up to people to decide whether this is something they're up to.
Some people have 5 thumbs on each hand while others get the chills when hearing the word 'electricity' - ok, this is not for those people (hmm..sounds like 'the King of Spades'..).

There's nothing wrong with going to the local store and buy a pre-assembled machine. But if you're up to it and have some talent you can have a lot of happy hours assembling one yourself - and save some bucks at the same time.

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Karl, Denmark
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"..and may The Force be with you too..."

[This message has been edited by kallikru (edited 06-04-2001).]

Usually to test out a power supply one will use a meter to check the voltages, but I wouldn't recommend that to a novice. Most definitely would not recommend opening up the power supply. Even unplugged, there are voltages there can could pack a wallop. (Same for the monitor). (Hey, if it smells burnt, it probably is. https://discussions.virtualdr.com/) Better to just replace it than to venture into the Land of Shock. It's worth the 40 to 60 bucks to avoid defribrillating oneself.
People will often keep upgrading like crazy; adding all sorts of peripherals, but don't think to upgrade that old power supply. So they end up running 4 to 8 IDE devices, a sound card, a vid card, a mobo, a NIC, and 512 mb of RAM on a 175 to 200 watt power supply. Go find a priest...your computer is about to die. You're overloading. Oh, it might go on for a while, but it's under a strain. Put your hand over the ps exhaust port. If it's mildly lukewarm, you may be OK; but if it's hot enough to dry your hair with, get ready for a breakdown.
(I'm just full of good news today, huh?) https://discussions.virtualdr.com/

kallikru,

My comments were addressed to some of the members giving questionable advise.

Such as:
1) zam1el, working on live machine in a puddle of water.
2) dacomputers, who does not use proper anti-static handling procedures because of improper understanding of anti-static tools. If Philgo were to use the procedure he suggested after reading dacomputer's post he would provide an excellent circuit path across his/her chest.

Other members need to be warned of the inherent dangers involved in working with electricity. If not for your own peace of mind then think of the potential liability that the website owners and advise posters may face if a member should sue after injuring himeself/herself.

In our lawsuit crazy world where people are sued for serving hot cofee (McDonalds), it pays to be protect yourself by making sure the end user understands the dangers involoved.

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Once, during Prohibition, I was forced to live for days on nothing but food and water. - W.C. Fields

i hear about kids that keep the case off . they think its cool i say its dumb, stuff could spill in it

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o4 breathalyzer is a safer lower drunk driving test in some states

so much information here . can someone make a quick outline for main points of safety?

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o4 breathalyzer is a safer lower drunk driving test in some states

I think we may need to clarify here between static and a full electrical charge when it comes to working inside the computer. The touching of the UNPLUGGED, I repeat, UNPLUGGED case chassis each time you go in is to discharge any minor static buildup, so as not to damage the mobo, cards, etc.. Any readers here should not infer that he/she is liable to get thrown to the floor by a major jolt by following that cautionary procedure. (This includes NOT wearing woolen/flannel clothing that builds up a charge and avoiding working on carpeting). The static discharge from those will not be enough to kill; it WILL "kill" the components though.

The two main high voltage areas, even if unplugged, are the INSIDES of the power supply and the monitor. Novices should avoid going in those--leave it to the techs. (Wrist strap? Actually, wearing a wrist strap while working inside a monitor is the very WORST thing you could do...you're inviting catastrophe). And again; best policy: never, never, never stick your hand inside a case when it's plugged in. The power switch may not be on, but there's power being fed into there. Not only do you stand a chance of getting a nasty shock, but you could get your finger sawed pretty good by a fan. Observe to see if everything's working, etc., then if not, unplug first, then poke around. With a little bit of caution and common sense, upgrading/exchanging parts is quite a simple procedure.

Just didn't want any of the readers getting too paranoic about upgrading/building their own systems. https://discussions.virtualdr.com/ s_brune makes a good point: be careful when giving advice that could involve potential danger. Explain yourself as thoroughly as you can. Just because something worked or turned out OK for you doesn't make it safe or "right" for others.
A lot of drunk drivers that were involved in fatal accidents had been "driving like that
for years" and "never had a problem before".
https://discussions.virtualdr.com/

It is important that people know about their equipment especially if they want to work on it. And any time the case is opened there are hazards. This is certainly not to scare anyone but to make you aware of the dangers. We do things everyday that have risks. Driving is a risk, so is eating, taking medicine, using power tools, chainsaws, etc.
There are many more, but when you talk about safety you are learning how to handle job tasks.

We want to make people aware of what is involved working on computers. Personally I enjoy this, but those that never have done it just where do they start to learn. All of us answering a question are trying to help someone else.

Now that you have seen that a power supply deserves respect, we have seen comments on the forums about changing out cards. Say, a video card needs changing for some reason. How does a person do this and what should he/she be aware of here?


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Theres far more danger inside a computer case than electricity.

How many times have you cut your fingers on those stupid metal plates that you have to remove to get the CDRom in.

And worst of all who has upset their spouse by laying the case on its side and ending up scratching a piece of furniture, now thats danger.

The owners manual to my home computer says
when opening the computer case,
to unplug the computer and press the power
button. Does this discharge those capacitors
then? Then all I'd need to worry about would
be the static electricity damaging components
rather than personal injury. Is this always
true, or is this some sort of superior
circuit design?

s_brune,
...and my comments were addressed to no one in particular. I just felt that your comments could be mis-interpreted as a general "keep out".

I'm sure we don't disagree (very much) in principal. People should not mess with things they don't understand, but the whole point here is that we try to give an understanding of these things - as you say yourself: "...making sure the end user understands the dangers involoved" - I agree fully. If some guys like to play with their lives then that's their problem - personally I don't.

But let's not overplay these dangers. I know there are people/lawyers living off lawsuits around the world (fortunately not in this country, where the laws assume a certain amount of personal responsibility - called "bonus pater familia"...sorry, I couldn't resist this little sort of off-topic), but people shouldn't let that stop them from pursuing a great hobby. As long a the rules of play are followed, why not play ball...?

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Karl, Denmark
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"..and may The Force be with you too..."

wheat1km: yes, that procedure is to "clear" any residual voltage. (But it's still not a good idea to poke around the insides of the power supply). But you can work on the mobo, RAM, hard drives, etc. as long as the system's unplugged (using the chassis touch or wrist strap). If you use the former, make sure you do it each time you go into the case and/or before handling a component.

Philgo, LOL That was funny. About time someone said something to break things up a bit. But as much as we are in "fear" of our spouses make sure your work is safe when you leave it for you families sake. There has not been anything said about making your famiy aware not to be poking around when you are not there. How do you do this? With children the first thing they will do after you say don't do something is exactly what you said not to do. So perhaps show them. Is this an issue?

BTW you contributers are doing a nice job and we are getting many views here. Let's see wasn't it JTDoom that was talkin about doing summaries. Correct me if I'm wrong on that. zorroonecrow was asking about summarizing because of the amount of information presented. This is something to think about. Where do you say this is just enough or this is to much. I would rather see to much than not enough and we can save these threads and re read later to get more out of it.

I will say this, there is information here I have never seen before. Of course There's alot of things I've never seen. https://discussions.virtualdr.com/



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Quote:

---

Originally posted by wheat1km:
The owners manual to my home computer says
when opening the computer case,
to unplug the computer and press the power
button. Does this discharge those capacitors
then? Then all I'd need to worry about would
be the static electricity damaging components
rather than personal injury. Is this always
true, or is this some sort of superior
circuit design?

---

No, Wheat, that does not discharge those capacitors. It only ensures that no more power is fed into those capacitors. If you wan't to be completely safe from what hides inside the capacitors then your have to unplug the ATX/AT connector from the mainboard too (the wide one).

The power supply (PS or PSU) contains a transformer, though, that transforms your 120/230 Volts to 12, 5 or 3.3 volts, and I've so far not heard of anyone being electrocuted by touching the unplugged mainboard. But always be wary when working with electricity.


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Karl, Denmark
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"..and may The Force be with you too..."

[This message has been edited by kallikru (edited 06-04-2001).]

My experience with computer case is that the outside is smooth and free of obtructions that will cut you, but be careful on the inside while you work as the edges of the metal can be very jagged. And if it catches you hand or arm it will more than likely cut you.
Just take it slow and easy and it is very simple to work on computers. But, if you have any doubt in you mind, I for one will not blame anybody for having it done.


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darn shifts

to change a light-bulb in a fixture, make sure the power is OFF. Not just the switch you use to flip it on/off.
You go kill the circuit at the fusebox.
why, you don't wanna get thrown off a ladder/chair/table/stepup.
hell, you don't wanna fall. period.
I tell you that it's no fun to touch the live end of a single 230V (and 110V kan KILL too)

in our dialect, we call that other thing a differential switch. Its mandatory.
the overall 300 milliamp differential, protecting ALL circuits comes from the main trip fuse.
A 30 milliAmpere differential is installed behind it for all appareil around kitchen, bathroom and the washing machine

if you are working alone, and know you gonne be alone until you finished, THEN there is no real need to put a poster up.
But when you are not alone in the house, you better make sure everybody knows you gonna switch some circuit off, and make sure it STAYS off.
best way is to pull the fuses out.
when you have them automats, switch it off, tell everybody, and rely on the switched powerstrip YOU use and can keep an EYE on.
some moron WILL switch the automat back on.
I believe it's called Murphy's LAW

GET that switched powerstrip.
you can switch off and stay grounded.

and yes, POWER OFF all peripherals, and disconnect every peripheral from case when you need do work inside the case

when you need remove cutouts, don’t bend metal with your bare hands.
Use pliers.
Hell, I use fine leather gloves AND pliers
Blood aint good for the mainboard.
Bleeding aint good for the human

One of these days Zam1el will have to change name
It Could become ZAPPED1el 

Listen, there is no one-up-ism involved when working on ‘tricity.
You get either killed or fired when you work unsafe. Think it over.



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You help someone with a similar problem if you tell us what worked.
When you do, please post solution in the original thread?
Kind regards, Jaak

jaak
if you are in the mains and to be safe lock it so no one can apply murphy's law to you. Might even want to put A second lock on it also.

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JTDoom and Kallikru, Your power acroos the pond is different than ours, in fact in terms of voltage it's higher. Please tie in your house voltage and your computer. Does the higher voltage you have go into the computer and then coverted to what the computer uses. In terms of safety are you at higher risk than with the "120V" we have here?



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No, not at all. The higher voltage means we're running at lower amps (since effect=Watt = Volt x Amp), and amps are what kills people, as someone wrote earlier.
So you COULD say we are a bit safer. https://discussions.virtualdr.com/ This reflects itself on our fuses/breakers. Here in DK normal "light"-fuses are set at max. 10 amps. And then we have "power"-fuses (for stoves, washing machines ect.) running 380 volts - fuses/breakers will then tolerate a max. load of 16 amps.

Since you "only" run at 120 volts in the States, this probably means your fuses/breakers will accept higher number of amps?

Our PSs here usually come with 2 settings, 120 V and 230 V (default here) - as yours probably do over there (with 120 volts as default), so it's basically the same PSUs. Here 230 V are put in but we get the same 12, 5 and 3.3 volts to the mainboards, as you do.

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Karl, Denmark
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"..and may The Force be with you too..."

Greengoose1
Both of my computers have provisions to run off of 240V as do most new machines. There is a switch on the ps that is flipped to the 240V side and the ps is factory wired to convert the higher voltage to that which is needed by the motherboard and all other components in the computer.

Also, we must take in the fact they use 50HZ while we use 60HZ. This will make a difference in how fast our harddrive, cdrom and the like will spin.

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Kallikru, I have a 200A ckt breaker panel. It breaks down into 50amp breaker for AC unit, 30A for dryer, 30A for water heater and the rest are 20a breakers. The wire size is 12G for the 20A, 10g for dryer - not sure on AC unit. In addition on the outside power pole is a transformer that has a dropdown line fuse. The voltage coming into the ckt brk panel is 220 which is split into 110v. If we run 220v appliances the bill is cheaper monthly (water heater for example).

For safety this is a three wire system so a mechanical ground is available for everything that is plugged in.

For those of you reading this thread, you have been exposed to AC electronics and knowing a litlle bit about this helps give an overall picture of how your computer powers up and some how to's on what to check safely if you need to . You sit in front of your computer doing "things". Now you should be getting an idea how the picture is put together. And as you sit in front of your computer safely, so should you be able to work on your computer safely.

For you quiet types that are following along, please remember no question in your mind is unimportant. So if you have one be sure to ask. https://discussions.virtualdr.com/



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Good Morning All, Received a couple of Emails regarding our subject matter. The feeling was that we were talking quite a bit about electricity and I have to agree. Let's move get back to safety and computers. Is there a need to talk about test equipment such as a vom or continuiy tester, pencil soldering irons (circuit board repair), or soldering irons (wire repair)? How to use them safely.

Using tools safely will also help us in our next segment on Cooling. https://discussions.virtualdr.com/

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