Black screen of death......

[ddavid 149]

O.K. - the conkerin' hero's back from Venice (no escape - Ed) and I thought I'd share a success story with you, that involves a screw-driver and a vacuum cleaner!

About six weeks ago, I up-graded my computer's memory from 1Mb to 2Mb. Now, I went about it carefully: went on-line; had a look around; got one of the sites to tell me what sort of DDRam I needed, and ordered the bits (from Crucial). When the card arrived (aren't they small?) I opened the box and stuck it in - easy peasy, or so I thought. Powered up - computer didn't like it much, kept talking to me in O.S. (which I can't understand....) 'Phoned the boffin, who said "It's probably the ribbon cables - swap them around", which I did, and, hey-presto, up came XP - brilliant. But wait a minute - or 5, as it turned out, what's the black screen for? Re-start, and the computer's O.K. again....

I won't bore you (they've probably nodded off anyway by now - Ed) with the details, but things got marginally better, until the BSoD (Black Screen of Death) stopped Pam in the middle of a complicated email and I was given two alternatives and, as it was raining and blowing a gale out-side, I took the computer apart.

This is where the screw-driver and vacuum-cleaner come in..... Now, I've been around computers for a number of years (Decades, more like - Ed) but I'd not actually hoovered a c.p.u. before, so - carefully un-screwing the fan - all was revealed: it was chock-full of dust, 2 or 3 mm of the stuff! "Away!", I cried - and the dust was removed. And I was lucky, I guess, 'cause the computer powered up fine, but more importantly, No More BSoD's! And a satisfied wife (That's an oxymoron you know - Ed)

So, a result - and a moral to the story: keep the inside of the box tidy - get that vacuum-cleaner out, ladies!!

Anyway, good to be back. More rubbish to follow (Like I said, No Escape - Ed)

Cheers - Dai. :mrhappy:

[allardjd 1,853]

Dai,

A good lesson there for all of us. So the new memory chips were just a red herring?

I'd say rather than an oxymoron, your term is more indicitive of a temporary situation. In my former career we used to refer to that sort of thing as being spring-loaded to the pissed-off position.

John

[mutley 4,487]

Good house keeping is the key!

I vacuum out my PC about every 6 weeks, it is surprising where the dust and fluff comes from, Mrs Mutley has no idea! ( I have to say here I "clean" the room where my PC is!)

Cheers

[MartinW 0]

I have a pet Gerbil that goes in with a miner’s hat on with a little lamp attached. He takes in a little dustpan and brush and does it for me.

:mrhappy: Actually, I confess, I too have used a vacuum cleaner on occasions, but very, very carefully.

Vacuum cleaners (due to the rapidly moving air stream) can generate static electricity.

Take care with your mega-powerful sucking machines chaps.

Good idea to leave the PSU plugged into a wall socket WITH THE SWITCH OFF so the case is earthed.

In the UK anyway, not sure about the Star Trek, radial circuit, no fuse except in the consumer unit, [John?] style wiring system in the US.

You see, us guys in the UK, just after the war, had hardly any copper left :sad: so we wired our houses and industry up with ring circuits to save on the precious copper. Personally I prefer the radial circuit approach best, like in the US, less complex despite the increase in cables and whopping consumer unit.

Sorry I'm boring again. :sad:

:wink:

[mutley 4,487]

** Translation for John **

When Uncle Martin talks of "earthing the case" he is talking about grounding it!

/babelfish

Good advice about the static electricity and I agree with you about the circuit type.

Cheers

[allardjd 1,853]

Uncle Martin,

I had to cogitate a bit on the ring and radial terms, but have it worked out I think. We no longer use fuses here, but rather small individual molded case circuit breakers on each radial circuit. They're located in the entrance panel or as it's most commonly called, the breaker panel - I guess that's what you're referring to as the consumer unit. They have dual functions, tripping instantly on fault current, but more slowly on a modest overload. In the latter case a circuit can, for instance, ride out a motor starting surge even if the current exceeds the nominal circuit capacity for a short time.

All circuits are three wire now, with a hot, neutral and separate ground, though both the nuetral and ground are at ground potential.

Ground Fault Interrupters, either in the circuit breaker box or at individual plugs are required by most jurisdictions for kitchen and bathroom circuits. These trip instantly when there is even a very small mismatch between the current in the hot and the neutral, in case a few milliamps are going to ground through a human body somewhere out on the circuit.

Household electrical accidents are rare here and those that do happen are usually the result of someone being incredibly stupid. Nothing is foolproof because fools are so ingenious.

See - I can be even more boring than you! :mrhappy:

[ddavid 149]

Jusy one question, John - have you a supply of these gems??

Nothing is foolproof because fools are so ingenious.

I can sense a new thread coming.........

Cheers - Dai :mrhappy:

[allardjd 1,853]

I do indeed, most shamelessly stolen from others.

One day I intend to publish Allard's Laws of Power Plant Maintenance. It will be great therapy for me.

John

[mutley 4,487]

*** Translation for Uncle Martin ***

Ground Fault Interrupters

Rcd's or RCCB's

All circuits are three wire now, with a hot, neutral and separate ground

Live, Neutral and Earth

Breaker Panel or Circuit breaker box

Consumer Unit

[/babelfish]

I'll shut up know, I can be more annoying than you guy's can be boring! :rofl

Cheers

[ddavid 149]

O.K., Joe - I give up. What is

babelfish

? Do tell!!

Cheers - Dai :?:

[mutley 4,487]

From Hitch Hikers Guide to the Galaxy :mrhappy:

http://babelfish.altavista.com/

[MartinW 0]

:mrhappy: Actually Mut I did understand john’s technical terms. :wink:

When I said fuses John: In the UK, we have a consumer unit [used to be called fuse box] into which the mains are fed. These days, like in the US they are fitted with MCB's [Micro Circuit Breakers] that protect each ring main. Also we have an RCD [residual Current device] that trips and cut's of the power to the ring main circuit at something like 30 milliamps, in the event that stupid old git Mutley mows over his lawnmower cable or does something equally insane. MCB's are quite sensitive too often tripping when a light bulb blows.

We also have radial circuits from the consumer unit for high load appliances like showers, cookers, standby immersion heaters, upstairs and downstairs lights etc.

The Ring mains themselves are for our 13amp sockets, wired as a loop or ring with 2.5mm Twin core and earth cable, basically a red black and green and white striped earth. And as for earth, the regs are very stringent; they make us ‘cross bond’ [check that one out Mut face] all of our pipe work.

Colour codes have now changed. Each socket is actually fed by two cables terminating at one MCB in the consumer unit and of course many sockets on one ring. Usually a ring for upstairs and one for downstairs. We are allowed to take spurs, [one socket] off a 13amp socket, or a switched fused connection unit for appliances like fires, or storage heaters. Notice I said fuse, we still have cartridge fuses, little baby ones in our plugs. :yes:

Quite complex as you can see, which is why I think your wiring with all radial circuits is easier to fathom. Loads of cables into your... breaker panel. :sad: But a much better system.

Beat that for boring. :sad: It even bored me.

[mutley 4,487]

in the event that stupid old git Mutley mows over his lawnmower cable or does something equally insane. MCB's are quite sensitive too often tripping when a light bulb blows.

We have a rcd unit I plug my hedge trimmer into. Twice, yes twice I have cut through the cable (purely for testing purposes!) and the blooming thing didn't trip, the fuse in the plugtop did. And yes every time a lamp blows on our downstairs lighting circuit blows it trips the mcb.

‘cross bond’ [check that one out Mut face]

:mrhappy: Ah, the old EC 14 and EC15 earth straps. Did I ever tell you Martin I worked for an electrical wholesaler for 6 years?

Next?

[mutley 4,487]

Sorry Dai we seem to have ..

It's starting to get a bit random!

Cheers

[ddavid 149]

No matter, Joe - gives me time to look up the IEE (oops! IET - I keep forgetting the new institution's name...) Regs. Great bed-time reading, you know! Now I could tell you a funny story about spurs - remember Danny Blanchflower? (Thinks - these young guys, so much to learn and so little time)

Cheers - Dai. :soft snoring:

[MartinW 0]

Ah, the old EC 14 and EC15 earth straps. Did I ever tell you Martin I worked for an electrical wholesaler for 6 years?

Yes apologies most sincerely for mutating this thread into a 'test the stupid old dogs knowledge, or lack of, and wipe that smile of his canine chops thread'. Don't worry, I'll do my very best to switch back to 'PC cleaning in a second.

Okay you manky old hound cop this:

I'm sure you just know the names as you 'sold them' :wink: rather than fitted them in an 'ace DIY style' like me, so I’ll test you on products only [maybe] And you must swear by almighty god that you will not use bablefish or any fish for that matter, not a google, not a yahoo or a Jeeves in sight, no sir.

What am I describing?

4 Core XXXXX Wire XXXXXXXX 6944X Min. length is 10m or on 100m drums

XXXXXXX cable is XXXXXXXXX by a sheath of XXXX XXXXXXXXX making it suitable for direct XXXXXX or use overhead without further protection. Use indoors XXX XXXXXXXXX, BASEC approved.

Anyway, back onto cleaning ones beloved PC. I find it depends very much on the design of the CPU heat sink, My Thermalright XP120 in my old PC rarely clogs with dust, however the Arctic Cooling freezer 7 Pro clogs quickly, simple because the fins on the cooler are so closely spaced.

:mrhappy:

[allardjd 1,853]

Beat that for boring.

Nope, can't touch that. You win, Uncle Martin.

By the way, do you know why AC is safer than DC?

You get 120 chances a second to let go of it!

John

[mutley 4,487]

Ok, I made it up (Not)

Cannot get what the XXXXX means a bit vague.

A) Steel wired armoured XLPE cable?

:mrhappy: The second one sounds as though you are talking about Firetuff or mineral insulated cable used in fire alarm systems. Or could be Arctic cable?)

Cheers

[allardjd 1,853]

suitable for direct XXXXXX or use overhead

...direct burial or use....

[mutley 4,487]

Oh I see it's an extended description of armoured cable. Let me see..

4 Core Steel Wire Armoured 6944X Min. length is 10m or on 100m drums

Armoured cable is covered by a sheath of wire armouring making it suitable for direct burial (Thanks John) or use overhead without further protection. Use indoors and outdoors, BASEC approved.

How's that gummy? :mrhappy:

[allardjd 1,853]

Mutley,

Re your hedge trimmer test...your circuit is probably fine. With that kind of event, it is very likely that you created a hard contact between the hot and one of the other conductors, which are at ground or earth potential. With that kind of dead short it's not surprising that the fault protection (fuse) opened. The fuse would probably have saved your life in this case but it only operated because the current was very high. A much smaller current can kill you and the fuse would not care one iota.

In fact, if the short you created happened to be between hot and neutral and didn't involve the ground conductor, the GFI would never see it regardless of the current level. GFIs are not an overcurrent device; they're looking for a mismatch between line and neutral, nothing more, nothing less.

To test the GFI or whatever your TLA for it is (I've forgotten, sorry), you should bleed off just one or two hundred milliamps, such as might flow through you if you accidently make contact. Use a resistor, say about 1K or 2K ohms (anything down to about 100 ohms would probably be OK) between the line conductor and a ground (but not the neutral). In that case the current will be far too low for the fault protection (fuse or circuit breaker) to operate, but the GFI should see the current mismatch between line and neutral and open the circuit.

You can then confirm what I'm describing by resetting the device and connecting the same resistor between line and neutral. There should be no trip in that case because there will be no current mismatch.

I'm sure I don't need to add the standard precautions for working with live circuits. You sound like you've been around the block once or twice, but still....be careful. Hertz hurts!

(Uncle Martin, please assign a BI [boring index]. It's so hard to judge your own work.)

John

[mutley 4,487]

Thanks John,

That explains it, the trip is 30mA.

Before trying your tests should I lick my fingers first?

I think I will leave the electricity alone, I got a wife and my "Hangars On" to support :wink:

Cheers

[MartinW 0]

Oh I see it's an extended description of armoured cable. Let me see..

4 Core Steel Wire Armoured 6944X Min. length is 10m or on 100m drums

Armoured cable is covered by a sheath of wire armouring making it suitable for direct burial (Thanks John) or use overhead without further protection. Use indoors and outdoors, BASEC approved.

How's that gummy?

Well done Mutley... nearly, you wouldn't have got ot withouit Johns help. full marks to John 5 to you.

[MartinW 0]

Be careful with your trimmer Mut. :giggle:

Don't forget John has 110 volts in the United States of electricity, we have 5 million mega killing volts, generated from a quantum singularity.

John will know better as to the difference in terms of killing potential as voltage is akin to water pressure and amps the gonad shriveller. :wink:

Is that right John, is your lower voltage safer or not?

(Uncle Martin, please assign a BI [boring index]. It's so hard to judge your own work.)

Well... hard to do for me also John as I like all this electrons cursing through conductors and electron hole theory stuff.

So... I would give it a zero boring Index. 10 of course would be totally boring and induce an immediate coma.

[allardjd 1,853]

I don't know what your voltage is, exactly, but understand it's roughly twice our 110-120. We also use 230 V for higher energy devices, water heaters, air conditioners, ranges, ovens, etc.

I wouldn't say your voltage is significantly more dangerous than ours. As you say, voltage is pressure, so if you make contact you might experience twice the current. It really comes down to how well grounded you are. The key is to not make contact. Neither voltage is high enough to jump even a small gap to reach you; you must make contact to have a problem.

It's my understanding that about 4 milliamps across the heart is enough to stop it. Worst case is said to occur by making contact on one side of the body and being grounded on the other.

In our system two phases are available at the panel, i.e. two "lives". Voltage between them is 230. Voltage from either to earth is about 115. The two lives are 120 degrees out of phase.