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#46
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O.T. Cleaning computer
"J. P. Gilliver (John)" wrote in message
... In message , Mr Pounder Esquire writes: J. P. Gilliver (John) wrote: In message , Mr Pounder Esquire writes: [] Oh, I've always earthed myself to a radiator before I take the desktop into the garage. Good idea, but voltage is relative - it's more important that you touch (an exposed metal part of) the chassis before touching anything inside - in theory, it probably doesn't matter if you're at 1 kV, if the chassis is also at 1 kV. (Well, I exaggerate for effect, but YKWIM.) If the chassis and you are both grounded, even better. Often achievable by leaving the mains lead (US: line cord) plugged in, assuming it's a 3-pin plug. I need to take it into the garage and take the panels off before I can touch the chassis. Then I have to find an earth. That might be one case where, indeed, you and the chassis are at the same potential (thus you're unlikely to cause damage by a discharge), even if that potential isn't earth potential. (Although I'm surprised you don't have a handy earth in your garage - don't you have power there, e. g. for a battery-charger? If so, I'd _hope_ it has earth terminals!) JPG Ever been frustrated that you can't *disagree* with a petition? If so, visit 255soft.uk - and please pass it on, too. If you leave the machine plugged in and just turn the switch on the PSU to OFF, the machine will still be grounded through the 3 prong power plug. So, just touch a metal part of the machine before touching any electronic part and both will be at the same potential. You don't need to find a different ground such as a radiator, etc. Don't fret about blowing a can of compressed air on the heatsink, just do it and get it over with. -- Buffalo |
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#47
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O.T. Cleaning computer
Buffalo,
If you leave the machine plugged in and just turn the switch on the PSU to OFF, That might once have been be good advice, but not so much nowerdays. These days computers can be "off" but still have parts of it powered so that, for example, pressing a certain (or any) key on the (USB!) keyboard will boot it. Some motherboards have a LED to show its still (partially) powered even when supposedly being off, but not all. Pulling the powercord and waiting for a minute or so (to give the capacitors in the power supply a chance to drain themselves) is the best way to go. With, or without actual grounding. So, just touch a metal part of the machine before touching any electronic part and both will be at the same potential. And that will be true even with power cable (and its grounding) removed. :-) Regards, Rudy Wieser |
#48
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O.T. Cleaning computer
I always wear a grounding strap if I'm going to
be handling something inside the inside the computer. As I stated earlier in the post this isn't just a ground problem with the computer any longer; all the outlets are open grounded which is why I have an electrician coming on the 9th to replace and check all the outlets. Robert |
#49
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O.T. Cleaning computer
The problem actually wasn't in the PSU but the APC
Surge Arrest which indicated a problem and when I put a testor in the sockets it showed open ground. All the sockets in the house except for one showed open ground. Robert |
#50
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O.T. Cleaning computer
"R.Wieser" wrote in message ...
Buffalo, If you leave the machine plugged in and just turn the switch on the PSU to OFF, That might once have been be good advice, but not so much nowerdays. These days computers can be "off" but still have parts of it powered so that, for example, pressing a certain (or any) key on the (USB!) keyboard will boot it. Some motherboards have a LED to show its still (partially) powered even when supposedly being off, but not all. Pulling the powercord and waiting for a minute or so (to give the capacitors in the power supply a chance to drain themselves) is the best way to go. With, or without actual grounding. So, just touch a metal part of the machine before touching any electronic part and both will be at the same potential. And that will be true even with power cable (and its grounding) removed. :-) Regards, Rudy Wieser Yes, I should have mentioned to make sure the outlet the PC was plugged into was grounded properly. I was talking about the switch on the PSU, not just turning the PC off. That switch on the PSU should disconnect the hot and neutral wires but leave the grounding wire connected. Perhaps some only disconnect the Hot wire. Using a grounding strap is excellent and about the best way, but just keeping one hand on a metal part of the PC and using the other hand to pick up the part will usually be good enough without going crazy getting an earth ground separate from the grounding in the outlet, If you use a radiator or grounding electrode conductor, then make sure the PC is not plugged in regardless if the switch on the PSU is OFF or not. Different potentials can exist by doing that. Overall, don't go crazy trying to find the best ground, etc. Use the grounding strap method and/or use my suggestion. -- Buffalo |
#51
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O.T. Cleaning computer
In message , R.Wieser
writes: Buffalo, If you leave the machine plugged in and just turn the switch on the PSU to OFF, That might once have been be good advice, but not so much nowerdays. As he's reminded you in a later post, he did say "on the PSU". I've yet to encounter a case where that isn't a real switch. (I have, however, encountered PCs - I suppose I should really say PSUs - where there _isn't_ a switch on the PSU itself. [] Pulling the powercord and waiting for a minute or so (to give the capacitors in the power supply a chance to drain themselves) is the best way to go. With, or without actual grounding. It's a good way to ensure things are discharged, but it actually _isolates_ the ground. Personally I've not found a case where such isolation has caused a difference in potential anywhere near big enough to cause harm, but ... So, just touch a metal part of the machine before touching any electronic part and both will be at the same potential. And that will be true even with power cable (and its grounding) removed. :-) .... I'd agree with the touch method. (Going the whole hog with a wrist strap that has a clip for the chassis is even better, but I wouldn't buy one just for the sake of it. YMMV.) Regards, Rudy Wieser -- J. P. Gilliver. UMRA: 1960/1985 MB++G()AL-IS-Ch++(p)Ar@T+H+Sh0!:`)DNAf "I'm a self-made man, thereby demonstrating once again the perils of unskilled labor..." - Harlan Ellison |
#52
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O.T. Cleaning computer
John,
As he's reminded you in a later post, he did say "on the PSU". I've read it. I didn't want to make a point of it. I have, however, encountered PCs - I suppose I should really say PSUs - where there _isn't_ a switch on the PSU itself. Same here. Just counted: from 9 'puters here three do *not* have such PSU switches. Thats one out of each three. But even for the ones that do have them I would not make any bets on them to work as expected. If there is anything I've picked up when learning to be an electrician is that assumptions like that will get you killed. Or, in this case, might kill your motherboard. Pulling the plug and removing it from the workingspace makes *certain* the power is off, and isn't any more difficult than using that (rather tiny and sometimes awkwardy placed) switch. Than again, may'be I'm just a bit over-cautious. :-) Personally I've not found a case where such isolation has caused a difference in potential anywhere near big enough to cause harm, but ... I have. On certain (dry) days just a few steps over the (no doubt nylon) carpet caused static discharges to occur when reaching for metal stuff like doorknobs. Repeat 30 seconds later and the same would happen. Luckily I didn't have to work on a puters innards there. :-) The "touch the metal frame" was considered always a good thing to do, even when wearing an earthing wristband. Largely because those tended to bleed the excess charge off rather slowly (forgot how many megs the series resistor exactly was), but also doing it automatically could save ones ass when either forgetting to reconnect the earthing after grabbing a coffee or simply when, on outside jobs, no earthing point or wristband was available. Regards, Rudy Wieser |
#53
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O.T. Cleaning computer
In message , R.Wieser
writes: John, As he's reminded you in a later post, he did say "on the PSU". I've read it. I didn't want to make a point of it. I have, however, encountered PCs - I suppose I should really say PSUs - where there _isn't_ a switch on the PSU itself. Same here. Just counted: from 9 'puters here three do *not* have such PSU switches. Thats one out of each three. But even for the ones that do have them I would not make any bets on them to work as expected. If there is anything I've picked up when learning to be an electrician is that assumptions like that will get you killed. Or, in this case, might kill your motherboard. Pulling the plug and removing it from the workingspace makes *certain* the power is off, and isn't any But does equally make *certain* that any earth connection it might have contained is also broken. I would say "leave it plugged in but turn off the power at the socket", but I'm aware that switched sockets, though the norm in BS1363-land, are the exception elsewhere (EU, USA). [I'm also under the impression that two-core - no earth - is commoner in the USA, even where the connector at the PC end is the IEC320 that _does_ have an earth pin. I may be wrong there however.] more difficult than using that (rather tiny and sometimes awkwardy placed) switch. Than again, may'be I'm just a bit over-cautious. :-) I think we're in agreement really. [] The "touch the metal frame" was considered always a good thing to do, even when wearing an earthing wristband. Largely because those tended to bleed I'd certainly do it. (Feeling better if knowing said chassis was also earthed.) the excess charge off rather slowly (forgot how many megs the series 1, usually, though only nominally (so ± 10% or even 20). resistor exactly was), but also doing it automatically could save ones ass when either forgetting to reconnect the earthing after grabbing a coffee or simply when, on outside jobs, no earthing point or wristband was available. Regards, Rudy Wieser -- J. P. Gilliver. UMRA: 1960/1985 MB++G()AL-IS-Ch++(p)Ar@T+H+Sh0!:`)DNAf Eve had an Apple, Adam had a Wang... |
#54
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O.T. Cleaning computer
John,
But does equally make *certain* that any earth connection it might have contained is also broken You seem to regard that earth connection as the holy grail. It isn't. I would say "leave it plugged in but turn off the power at the socket" You again assume that everything works as intended, possibly even (just not in this case) betting your life on it, even though a simple, rather effortless precaution would do away with such betting. Even in this thread you could have read that Mark Twain mentioned that he had a problem with *multiple* sockets not being earthed (because of a failure somewhere). In the same way a dual- or single-wire socket switch could fail - or be mis-wired! - leaving a hot wire to enter a device, just not with a neutral out of it. Why take that chance ? But granted, due to, in this case, the PSU working like an isolator (or should be!) you would not even be aware of such failures. I think we're in agreement really. I think we are in regard to that the potential difference should be(come) zero, just not on how to accomplish it. :-) I'd certainly do it. (Feeling better if knowing said chassis was also earthed.) In that case use a *single* wire, posibly connected to the frame by way of an alligator clip or alike. Regards, Rudy Wieser |
#55
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O.T. Cleaning computer
R.Wieser wrote:
John, But does equally make *certain* that any earth connection it might have contained is also broken You seem to regard that earth connection as the holy grail. It isn't. I would say "leave it plugged in but turn off the power at the socket" You again assume that everything works as intended, possibly even (just not in this case) betting your life on it, even though a simple, rather effortless precaution would do away with such betting. Even in this thread you could have read that Mark Twain mentioned that he had a problem with *multiple* sockets not being earthed (because of a failure somewhere). In the same way a dual- or single-wire socket switch could fail - or be mis-wired! - leaving a hot wire to enter a device, just not with a neutral out of it. Why take that chance ? Mark Twain? (I know this is unrelated, and my apologies for that, but I thought Mark Twain died a century ago. So is the OP just assuming his name? Seems weird). |
#56
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O.T. Cleaning computer
In message , Bill in Co
writes: R.Wieser wrote: John, Hi Rudi. But does equally make *certain* that any earth connection it might have contained is also broken You seem to regard that earth connection as the holy grail. It isn't. I don't. On the whole, I consider it preferable to have it, but having the operator and the chassis at the _same_ potential is more important from the point of minimising the chance of damage _to the equipment_. Minimising the chance of damage (including death) to the _user_ probably _is_ best served by yanking out _all_ connections, as you recommend. I would say "leave it plugged in but turn off the power at the socket" [] Even in this thread you could have read that Mark Twain mentioned that he had a problem with *multiple* sockets not being earthed (because of a failure somewhere). In the same way a dual- or single-wire socket switch could fail - or be mis-wired! - leaving a hot wire to enter a device, just not with a neutral out of it. Why take that chance ? In the UK, the socket switches are part of the socket. (I've never liked them - mainly because I don't see the point of them - but I doubt they _can_ be miswired [and still actually appear to work]. [An extension _lead_, of course, which may be _feeding_ some switched sockets, certainly _can_ be, of course.) A mains lead (line cord) that _only_ has the earth/ground wire present - i. e. cannot supply power - is arguably useful in some circumstances. (I do not possess such.) Mark Twain? (I know this is unrelated, and my apologies for that, but I thought Mark Twain died a century ago. So is the OP just assuming his name? Seems weird). There's been a poster using that identity here for some time (years I think). It could be his real name, though I _suspect_ not. -- J. P. Gilliver. UMRA: 1960/1985 MB++G()AL-IS-Ch++(p)Ar@T+H+Sh0!:`)DNAf Personally, I don't like the Senate idea, I don't like the idea of having to elect another bunch of overpaid incompetents. I don't like the idea of having wholesale appointments by the PM of the day for domination of the second chamber. I like anachronism. I like the idea of a bunch of unelected congenital idiots getting in the way of a bunch of conmen. - Charles F. Hankel, 1998-3-19. |
#57
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O.T. Cleaning computer
On Thu, 3 Jan 2019 01:20:15 +0000, J. P. Gilliver (John) wrote:
Mark Twain? (I know this is unrelated, and my apologies for that, but I thought Mark Twain died a century ago. So is the OP just assuming his name? Seems weird). There's been a poster using that identity here for some time (years I think). It could be his real name, though I _suspect_ not. Well he signs his posts as Robert. -- Regards - Rodney Pont The from address exists but is mostly dumped, please send any emails to the address below e-mail rpont (at) gmail (dot) com |
#58
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O.T. Cleaning computer
John,
but I doubt they _can_ be miswired [and still actually appear to work] As english sockets are constructed in such a way that the plug can only be inserted in a single orientation and therefore most likely only switches the (supposidly) "hot" wire, it would be easy: Just swap, when wiring the socket, the neutral with the phase wire. And as (re-)connecting such sockets can be done by the man of the house himself (or a bungling electrician) .... The circuit will still be open when "switched off" (no current can flow, causing the attached device(s) to stop working), but the "hot" wire will still enter the attached device. Worse, over what is assumed the neutral wire ... An extension _lead_, of course, which may be _feeding_ some switched sockets, certainly _can_ be, of course. Nope. Not when the single-orientation wiring is followed (which is ofcourse subject to the same mistake as above). Regards, Rudy Wieser |
#59
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O.T. Cleaning computer
I haven't been following this thread, but
since my name came up,.. here's the explanation. I was using another common username when it was suggested I change it to something more unique so it would be more easily recognizable. I'm a history buff and just choose Mark Twain that's really all there is to it. Robert |
#60
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O.T. Cleaning computer
Yes Mark Twain died a century ago but
Why does it seem weird? It's just a username. I could of put anything and just decided to use that. Robert |
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