Why oh why.... TM auction fail.

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#1733421 9-Mar-2017 07:26

richms:

Person I know who takes no precautions whatsoever seems to have terrible luck with ram failing. Yet mine which I get the cheapest stuff they sell generally seems rock solid.

Not sure if there is any connection at all, but ram would be one of the easiest to damage with all those data lines sitting unprotected at all on the gold edge connectors etc.

Different people actually generate different amounts of static, it depends how much they sweat, what clothes they wear, humidity, etc etc etc etc.

If you are working on a PC, leave it plugged in with the mains switch on the WALL TURNED OFF. <- Read carefully, turn the switch OFF

You can then touch the chassis to discharge yourself and hold it while you handle the RAM, easier still is to clip your wrist strap to the chassis

I have an antistatic mat that I lean my elbows onto. Same diff.

mclean

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#1733546 9-Mar-2017 10:41

sir1963: If you are working on a PC, leave it plugged in with the mains switch on the WALL TURNED OFF. <- Read carefully, turn the switch OFF.

Getting a bit off-topic, but to make electrical stuff safe to touch you need to use an isolator, not a switch. You shouldn't assume the switch on a socket outlet meets the safety requirements of an isolator. Pulling out the plug does.

richms

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#1733552 9-Mar-2017 10:47

It doesnt matter if its connected to anything, since you want the bag the stuff is in, the case, and you to all be at the same potential. If the case and mobo are earthed, you are earthed but you pick ram up that has static on it, then the same discharge happens, same damage. "Oh but I'm earthed" doesnt solve everything.

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#1733555 9-Mar-2017 10:51

mclean:

sir1963: If you are working on a PC, leave it plugged in with the mains switch on the WALL TURNED OFF. <- Read carefully, turn the switch OFF.

Getting a bit off-topic, but to make electrical stuff safe to touch you need to use an isolator, not a switch. You shouldn't assume the switch on a socket outlet meets the safety requirements of an isolator. Pulling out the plug does.

Given the live is the only switched component of a standard power point you still have a connected Earth and Neutral.
If in the case there is a fault at the board and the Earth or Neutral is livened you will have a very interesting time.
These days with a MEN link and RCD's your pretty safe.

sir1963

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#1733557 9-Mar-2017 10:56

mclean:

sir1963: If you are working on a PC, leave it plugged in with the mains switch on the WALL TURNED OFF. <- Read carefully, turn the switch OFF.

Getting a bit off-topic, but to make electrical stuff safe to touch you need to use an isolator, not a switch. You shouldn't assume the switch on a socket outlet meets the safety requirements of an isolator. Pulling out the plug does.

Pulling the plug also means it not earthed.

Given that the voyages inside a PC are low (the power supply is another issue) there is no shock risk

The power being OFF at the wall means it can not be accidentally turned on, inserting RAM into a live machine can be death to the RAM and mother board.

The earth chassis will seriously help anti-static requirements.

Yes you ARE better off with an earth point of your bench (GND wire directly to the earth peg) and using an earth strap (they should have a 1M Ohm resistor in series)

but when you are no in a position to do this, its better than nothing.

ANYTHING that has mains/high voltage exposed, e.g. audio Amps, don't do this. If you must work on something like this live, use an isolating transformer ALWAYS.

And at the very very least, put your electronics workbench ALL onto an RCD, yes they trip, but thats far better than being dead.

AND, if you do not KNOW what you are doing (i.e. outside of your area of competence), do nothing.

RunningMan

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#1733606 9-Mar-2017 12:20

sir1963:[snip]

Given that the voyages [voltages?] inside a PC are low (the power supply is another issue) there is no shock risk

The power being OFF at the wall means it can not be accidentally turned on, inserting RAM into a live machine can be death to the RAM and mother board.

The earth chassis will seriously help anti-static requirements.

My emphasis added.

IMHO this is potentially very unsafe advice. Whilst the logic board may be running at a harmless voltage under normal operating conditions, the above method affords no protection from a fault in the power outlet, and/or in the power supply of the device being serviced. A fault or combination of faults in either could lead to parts, including the case having voltages with respect to earth that are dangerous to the person servicing them.

Any item being serviced should be isolated from the mains supply, not just switched off.

Rikkitic

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#1733687 9-Mar-2017 13:53

I have done that kind of thing for most of my long life and I am still here. I don't claim special knowledge, but I do think there is a slight obsession with risk in this country. You can also get hit by a bus crossing the street. Some risks are serious enough to be worth avoiding, others, though not impossible, are highly unlikely. What is the actual risk of a PSU developing a failure that would put deadly voltage on the case (impossible, I would think, with that big fat earth plug always present) or on one of the low voltage circuits (would most likely make itself well-known with fizzing, popping, acrid smoke, all kinds of other alarming things that might cause most people to think maybe I shouldn't replace the RAM right now). There needs to be some perspective on this.

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richms

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#1733723 9-Mar-2017 14:28

When did you actually check that your earth is working? Plenty of questionable quality power supplies around, could also have had previous water damage or similar that you were not aware of which has made a nice path for it to flash over at just the wrong time.

Richard rich.ms

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#1733741 9-Mar-2017 14:46

Hasn't happened. Maybe could. Probably won't.

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sir1963

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#1733752 9-Mar-2017 15:14

richms:

When did you actually check that your earth is working? Plenty of questionable quality power supplies around, could also have had previous water damage or similar that you were not aware of which has made a nice path for it to flash over at just the wrong time.

Do you drive ?

You are far more at risk driving.

There is a world of difference between installing some extra RAM and working on a non-working/Damaged appliance.

Oh, and as I stated, ALWAYS have an RCD , my work bench has a 10mA one, not the 30mA consumer ones.

If you home and tools are in poor condition that they become a safety risk, you have bigger things to worry about

and if you don't know what you are doing, DONT do it.

So if you are one of those morons who think there is no such thing as static electricity, then DONT, I really mean DONT do anything you're an idiot waiting to screw up big time.

mclean

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#1734279 10-Mar-2017 10:44

Rikkitic: I have done that kind of thing for most of my long life and I am still here. I don't claim special knowledge, but I do think there is a slight obsession with risk in this country. You can also get hit by a bus crossing the street.

I agree about the obsession thing. In many ways electricity is more dangerous than a bus (unless you are deaf and blind). The thing is you are always given a simple way to isolate electrical equipment - the rules require it. The simple way to isolate a plug-in appliance it is to pull out the plug.

sir1963

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#1734334 10-Mar-2017 12:08

mclean:

Rikkitic: I have done that kind of thing for most of my long life and I am still here. I don't claim special knowledge, but I do think there is a slight obsession with risk in this country. You can also get hit by a bus crossing the street.

I agree about the obsession thing. In many ways electricity is more dangerous than a bus (unless you are deaf and blind). The thing is you are always given a simple way to isolate electrical equipment - the rules require it. The simple way to isolate a plug-in appliance it is to pull out the plug.

Have you ever tried fixing anything electronic ?

When unplugged the power supplies all read 0V, wonder if its a power supply fault....what do I do....

richms

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#1734335 10-Mar-2017 12:09

sir1963:

Have you ever tried fixing anything electronic ?

When unplugged the power supplies all read 0V, wonder if its a power supply fault....what do I do....

Use an isolated power supply while reparing it. Isolation transformers go for near nothing on trademe now when people are cleaning out grandpas garage etc.

Richard rich.ms

sir1963

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#1734337 10-Mar-2017 12:15

richms:

sir1963:

Have you ever tried fixing anything electronic ?

When unplugged the power supplies all read 0V, wonder if its a power supply fault....what do I do....

Use an isolated power supply while reparing it. Isolation transformers go for near nothing on trademe now when people are cleaning out grandpas garage etc.

Yep use them at times too, but if I am simply installed a New HD or RAM into a working computer then no, switch off at the wall is fine, even if the switch failed (Extremely unlikely)

the secondary low voltage inside the computer is still electrically isolated from the mains.

Rikkitic

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#1734354 10-Mar-2017 13:05

I don’t know how people used to do it here, but when I was young, in the 1950’s, the only way to learn about the electronics of that time was to play around with old radios and to design vacuum tube (valve) circuits. There were no solid-state devices, other than the odd selenium rectifier. If you wanted to know how an amplifier or oscillator or any other circuit worked, you needed valves and you needed deadly voltages to make them function. Most valves required at least 150 volts or more on their anodes. Mains power wasn’t earthed at all. If you accidentally put your finger in the wrong place while your arm brushed the chassis, you were simply dead.

I started playing with these voltages at around the age of 10. My father was an engineer and the first thing he taught me was how to stay safe. The secret is mainly just to think before you touch, and to make sure things you think are not electrified really are not electrified. At the age of about 12 I scored some old TVs (massive things in those days) and tried to produce hydrogen from electrolysis by using the 20,000 volt horizontal oscillator supply. It didn’t work but I didn’t electrocute myself either.

You can do wonderful things these days with digital kits and safe battery power. I wish we had had those things when I was young. But triodes and pentodes were pretty cool as well and wiring discrete components together gave a good understanding of how things worked.

It is sensible to be prudently cautious with things that can kill you but having grown up playing with things that could kill me has also taught me not to be unreasonably fearful of them. Electricity is something to be respectful of, not to be scared of.

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