Electricians'/IT technicians' help again please.

[Rat]

I'm generally fine with computers, but I've always been hopeless to mediocre with electrics generally. So perhaps someone can educate me.

A few months ago, I related a story wherein I replaced the fuse on my PC with a 13 amp one by mistake (instead of 5 amp).

Still, my PC is blowing the fuse with quite some regularity. Only about once every month or so, but enough to be a pain.

What could be causing this to happen? The PSU is a different one (though still a 400W one), as I killed the last one putting what I believe to be the wrong fuse in it, so it's unlikely to be a faulty psu. I'm living in a different house, so it's definitely something wrong with the computer.

It occurs to me that perhaps it should never have had a 5 amp fuse in it, but the only other size is 13 amp, which seems a little heavy for an appliance that draws 300-400 watts at 240 volts. I always get these calculations confused, though.

Is there a single faulty component that could cause this, or am I going to have to resort to the old IT methods of removing bits one by one, which would take ages to diagnose a problem that only occurs once a month, and unreliably at that?

For the record, we're talking an Athlon 2600+, 512 MiB DDR, MSI nForce mobo, two hard drives, two optical drives, Radeon 9200.

Cheers,
Rat.

[Skeptoid]

My guess is an intermittent short in the power cord.

[Rat]

It's certainly an idea, but the power cord is changed since the first time it blew. It's been the same one since then, though, so I'll try changing it with the kettle or printer. Or just nick one from work.

Cheers,
Rat.

[ShowMe]

Pick up a cheap UPS. It's possible that your computer is fine & it's your provider power that's the problem.

The UPS will also act as a surge protector.

[Darat]

Originally posted by ShowMe
Pick up a cheap UPS. It's possible that your computer is fine & it's your provider power that's the problem.

The UPS will also act as a surge protector.

I'd start with just getting a surge protector - it's cheaper! If that solves the problem it may be worthwhile getting your house circuit checked out.

[Rat]

I do have a decent surge protector. I don't have a ups, but I'm fairly convinced that it's not a problem with the supply. As I say, I've moved house since it began, and nothing else is blowing fuses, even from the same powerpoint. That said, I don't know what I'm talking about; it's just that someone I know who does know a bit about electrics (but not computers) says the machine must be drawing too much power, rather than the supply pushing too much.

Cheers,
Rat.

[Zep]

Surge protection.

If you can find someone who can put a Dranetz recorder (http://www.dranetz-bmi.com/products/products.cfm) on your power line for a few days (it records power condition) then that may show up something regular. Eg. your off-peak water heater cutting in may be spiking the lines in your house - OK for the kettle, but bad news for the PC. Also, note that repeated smaller spikes can be just as damaging as one big one.

[Soapy Sam]

Rat- at 400W, a 3 Amp fuse should be adequate. 5 would cover you for momentary surges on startup.

If it's blowing 13 amp fuses there's something seriously wrong.

Is this the fuse in the 3-pin plug you mean?

There is nothing in a PC that could possibly draw that sort of current, except the power supply itself, so it's either that , or as skeptoid suggests , an intermittent short in the power cable.

Does it happen at startup? That would suggest a momentary overload at the power supply. Or a fan locked up.
Does it happen when some part of the setup is being moved?
Do any peripherals draw power directly from the PC? A laser printer for example?

[Rat]

Hmm. Always happens when I'm out at work, but then that's 10 hours a day, so it's not unexpected. So I suppose it could be something else kicking in at a certain time. The event log shows nothing at any particular time. Well, except a bad block on a hard drive - probably time to get round to a proper backup procedure.

It is the fuse in the plug that blows, and it's never at startup. The scanner draws power from usb, but it's not often plugged in, so I can rule that out.

I suppose a ups isn't a bad plan. The whole ac/dc/ac/dc conversion thing should flatten things out. It's an expensive solution, though, I expect.

The whole thing started when I tried to silence the pc, but I suspect that's a red herring. Got a silent psu (but back to the jet engine one now) and a flower cpu cooler. The cpu cooler shows no problems, and if anything were overheating (the cpu runs at about 60c) I'd expect the machine to bleep and then shut down, but not blow the fuse.

I'm thinking of upgrading various bits soon anyway, which may solve the problem, but I'd still like to know for sure.

Cheers,
Rat.

[ShowMe]

Originally posted by ratcomp1974
As I say, I've moved house since it began, and nothing else is blowing fuses, even from the same powerpoint.

I missed that part. In that case I would look at serial devices first (modems or COM cards). Those are usually the things that get fried first, and if it's only a "little" toasty it might occasioanlly draw too much power.

One other thought...maybe it's your monitor. Do you turn your monitor off when you leave?

[Rat]

Sometimes I switch the monitor off (that is, to standby), sometimes I leave the power-saving to do it for me. Couldn't say whether it's one or the other, but they amount to the same thing. No way to turn the monitor off without pulling the plug, unfortunately.

As far as I can recall (I usually leave the case off, but it's currently on) the only card I have in any slot is the pci adsl modem. Oh, and an agp graphics card, of course.

I guess I'll try changing the lead (to be sure) and see if it happens again.

On a time-tracing note, can anyone think of a way to write a trivial event to the event log every couple of minutes or so without taking too much cpu power? That at least would give me an idea of whether it's happening at a particular time.

Cheers,
Rat.

[Soapy Sam]

Trivial? Sure. Enable Windows Auto Update.:D

I suppose you could write a script to print the time to a txt file every so often.

Or use the task scheduler to do so.
Or get a cheap mains electric clock and wire it across the plug. (Or feed one from the PSU).When the fuse goes, the clock stops. At least you then know when it happens, which might tell you something.

Definitely change the cable- swap with an old kettle or something. Can't hurt.

Check to see nothing else on the same ring main could be causing a surge. (Fridge compressor, washing machine?)

I keep thinking it comes back to the power supply. Recheck all the connections. Bad connector somewhere?

[mickky]

Being familiar with all things electrical (less so with the inner workings of printed circuit boards) I would be inclined to think that an automatic process that the computer enables (while you are away from it) is causing some sort of ground (earth) fault. You have stated that the fuse which blows is in the plug-an arrangement encountered in the UK and other parts of Europe-not in North America.

I'm obviously speculating here, but if you have moved, this would eliminate the possibility of surges from your supplier, (You would have dmaged other components in your home with that kind of current) and the mains cord is new; probably, something in the system (frames, shielding, or the like) is allowing a surge to ground (earth).

In any case DO NOT install another 13 amp fuse! Doing so could cause a dangerous overheating situation the next time this problem occurs. 400 watts does not draw a lot of current, but keep in mind it only takes 0.075 amps to cause your heart to fibrilate.


I could be totally wrong here, but explore all avenues...

[Darat]

Originally posted by ratcomp1974
Sometimes I switch the monitor off (that is, to standby), sometimes I leave the power-saving to do it for me. Couldn't say whether it's one or the other, but they amount to the same thing. No way to turn the monitor off without pulling the plug, unfortunately.

...snip...

Are you powering the monitor from an outlet on the PC's PSU? That's not something I'd ever recommend.

[richardm]

It might be worth checking the socket on your PSU. I used to have one that had a slightly larger-than-spec socket, and the cable could slowly work its way loose. Sometimes this would just remove power from the PC, and sometimes it would take the fuse with it as it went.

In the end I wound a layer of gaffer tape around the end of the plug and pushed it firmly home - problem solved.

[MRC_Hans]

Are we to understand that you have repeatedly blown 13 amp fuses?? 240V and 13 amps, thats over 3000W :eek:! Nothing electronic draws that kind of "juice" and lives. So possible culprits should narrow down to plug, cable and the socket in the PC (although that is usually integral with the PSU, which you say you have changed). There are some filter condensers built into the cable socket, but with that kind of power, they would probably fry.

Mmm, are you SURE its a 13 amp? And not a 1.3 amp?

Hans

[jimlintott]

To see when it was happening I'd write a batch file.

Something like:

sleep 120 #wait two minutes
echo 'a string' > AFILE #create a file
BATCHFILE #run the same batch file again

This should (in theory) leave a file that will be time stamped within two minutes of the failure.

(Please note : I don't use Windows and haven't written a DOS batch file for many years but I see no reason why this shouldn't work.)

[Soapy Sam]

Hans I'm sure he's right. 13 Amp is a standard fuse supplied in most detachable British 3 pin plugs. I have often wondered why. Apart from fan heaters , practically any appliance should have the fuse replaced with a 5 or 3 amp. These are the commonest available ratings. I never saw a 1.3 and don't believe such a fuse is available here.

Like you, I can't imagine any pc component blowing a 13 A fuse, which is why I lean to eithera fault in the cable or at the PSU

[Thumbo]

Originally posted by ratcomp1974
Hmm. Always happens when I'm out at work, but then that's 10 hours a day, so it's not unexpected.

Yikes! If it's blowing a 13 amp fuse, something is seriously broken: that's a lot of curent, so something is also getting very hot. Possibly red hot - your typical 1kW electric heater only takes four amps. And you're leaving it switched while you are out at work? I hope your fire insurance is up to date.

Seruiously, never leave this computer plugged in and unattended until you get this fixed. It is a fire hazard.

[MRC_Hans]

Well, whatever is repeatedly blowing 13 amp fuses must leave some traces.

Mmmm, how often has it happened?

Hans

[TillEulenspiegel]

Wow Lot of advice here, mostly good. The bottom line is that a 13@ fuse @ 220v is a major short ..period. You don't want to come home to a fire or destroyed house so until You find out whats blowing the fuse , You might want to unplug the computer entirely unless being used.

There are lots of suggestions about the culprit here , one that isn't mentioned is a safety feature found in some power supplies . It's called a crowbar circuit. What it does is if it sees to much current draw or or leakage or a power spike from the house power, lightning strikes and line transients occur all the time ( like where I live in Tampa Fl ...) it presents a direct short to blow the fuse and protect the rest of the down the line components . If this happens sometimes ( especially if it happens more then once ) the circuit can get fussy.

Get a power strip that has line protection. That works by presenting a short to power surges and if it trips You know the the incoming power is to blame. good luck

Bottom line unplug the damn thing before it becomes a flaming inferno while your at work.

[Kopji]

Saw a similar problem involving the little recessed 110V/240V switch once. Might unplug the PC and work the switch a few times to clean the contacts.

Most likely is the line voltage though. Another defective device on the output of UPS might set it off, (like a laser printer).
The UPS tends to isolate the output so if one device is bad it might cause another to blow.

Might try unplugging everything but the PC and see if it goes away.

[a_unique_person]

I've said it before and I'll say it again, there is no computer problem that can't be solved by throwing enough money at it.

[mickky]

Speculation, part 2...

People here with much more familiarity with how a computer works can correct me, but...

If the power management program on your computer that powers down your monitor, hard drive etc., enables some switch in the PSU, this switching may be causing the fault.

I say this since you have stated it happens when you are away from the computer. I'm not sure if this 'switch' actually exists, but from what you're saying, it may be a bad PSU.

Kopji:
'Might try unplugging everything but the PC and see if it goes away.'

I'd do that first, too. Make sure you're at home when you run these tests!

[evildave]

FUSE?

What the heck is there a fuse in there for? There shouldn't be a user servicable fuse in any MODERN power supply unit....

Never mind, it doesn't matter.

Replace the power supply. Problem solved.

Even the most expensive, highest quality power supply for a desktop shouldn't run you more than $80. An adequate one will cost less than $20. Can you afford $12 for a new 400 Watt power supply? How about if AC gets into your hard drive? Can you afford that?

The first time a PC has any sort of power fault, treat the PSU as truly dead, and do not try to "revive" it. It's never, ever worth it.

The only part on a power supply unit that's worth bothering with is a noisy fan, and that's only if you have a fan of the right size, and a soldering iron handier than another whole power supply.

http://www.pricewatch.com/ shows a great, steaming pile of power supplies for under $20.

Start THERE.

Kopji
If there's a laser printer plugged into a UPS, there shouldn't be. Those are power-hungry beasts with a heating element, and guarantee the UPS will be of practically no use at all if the power goes out while the laser is on. All but the biggest, priciest UPS manuals tell you not to plug a laser printer into them.

mickky
Gah! There are no 'power management' settings that will blow a fuse. If such a "switching" fault exists, it's in the power supply unit, and once again replace it.

[Darat]

Originally posted by evildave
FUSE?

What the heck is there a fuse in there for? There shouldn't be a user servicable fuse in any MODERN power supply unit....

Never mind, it doesn't matter. ...snip...

It may not matter but I thought you might like the information anyway. ;)

He is not talking about a fuse within a PSU, he is talking about the fuse in the plug of the power cord. All* UK household plug sockets require a 3 pin, fused plug.

(*There are exceptions such as electric shaver sockets.)

[evildave]

Doesn't matter.

It should be obvious that the power supply is blowing the fuse, if you've already replaced the cable. Replace the power supply. At best, it will eat fuses. At worst (very rare), you'll let the 'magic smoke' out of far more expensive parts of your computer, even things plugged into your computer.

Yes, taking practically the whole box apart is typical in this operation. There's usually OTHER stuff that has to come out to get the power supply unit out. Fishing bundled wires out from behind things, and unplugging lots of plugs. None of it is rocket science. Just make sure you get the same kind of power supply (AT, ATX, whatever), and at least as many watts of output (more is better, but equal is adequate), and then pay attention to what parts went where.

[mickky]

mickky
Gah! There are no 'power management' settings that will blow a fuse. If such a "switching" fault exists, it's in the power supply unit, and once again replace it. [/B][/QUOTE]


Re-read the post...where do I say Power Management settings blow fuses?

and as I said-maybe a bad PSU!

[Captain_Snort]

As EvilDave said, replace the power supply.


I had a PC that constantly crashed, even after I changed the mobo. I took the PSU out, took it apart, gave it a good going over with a smallish paintbrush to remove all the dust that had built up, and hey presto, works like a dream now.

[evildave]

Originally posted by mickky
mickky
Gah! There are no 'power management' settings that will blow a fuse. If such a "switching" fault exists, it's in the power supply unit, and once again replace it.


Re-read the post...where do I say Power Management settings blow fuses?

and as I said-maybe a bad PSU! [/B][/QUOTE]


If the power management program on your computer that powers down your monitor, hard drive etc., enables some switch in the PSU, this switching may be causing the fault.

If I've misinterpreted your post, then sorry, but that sounded a bit like you're blaming APM, which if you read a LOT of posts by people who have computer faults, isn't a surprising sounding assertion (for being dumb).

The only switch there is in the power supply is the one to switch on, and switch off. The rest is motherboard switching logic and a requirement for some "always hot" low voltage leads comming out of the power supply. NO WAY it could do anything like blow a fuse on a power cord from there.

[evildave]

To Novices:

Do keep in mind that the ONLY high voltage present in an ATX power based computer is in that ATX power supply box, and it does have some capacitors in it that can hold a nasty, surprising charge after power has been removed (especially if there is an electrical fault), like a burnt trace, or blown inductor. If you don't know what a capacitor or inductor is, especially don't open it up.

They're cheap enough to replace outright. Especially don't "clean it", if that means run it through a dishwasher, or spray it down with carburetor solvent, or whatever else to you.

Just replace it outright. I mean it. I'm not going to be the one to contribute to an episode of 'HCF' (halt, catch fire) and a 911 (or whatever) call because someone mentioned "scrub it" and it fixed his particular problem once.

110VAC is bad enough. Personal experience has taught that 220/240 is actually more than twice as bad to feel (or find yourself across the room from, wondering how you got there, because your heart wasn't beating right for a little while).

[MRC_Hans]

To be exact, 240V is four times worse than 120V in most situations, since it will dissipate four times as much power in a given load (which could be you :eek: ).

I did read one of the early posts as if the PSU had already been changed, but if not, as Evildave says, do it now.

There are parts in a PSU that have potential to blow fuses and survive to do it again later ;), especially if there is a phase correction circuit in your PSU. A phase correction circuit basically works by chopping the the AC voltage to little bits and feeding it to a capacitor. This operation involves a big ugly power transistor connected more or less directly across the power terminals (OK in series with a small inductor, still..), and if the circuitry controlling this decides to let it stay turned on for a few milliseconds, then ...*POOF!*.

- And that transistor might be big and strong enough to survive the action.

Hans

[Rat]

OK, all in all, I guess the psu is the first thing to go for. It's not on all day at the moment anyway, as the hard drive just died, so I'm waiting on a replacement. (Running Knoppix in the meantime).

I have indeed changed the psu once, but that was after the first time, which I suspect may have been a different cause That was the one that I blew by accidentally putting a 13 amp fuse in. And no, that wouldn't cause it to blow; just perhaps to blow more spectacularly.

I suspect, as some have suggested, that something is just shorting to earth. Replace cable, replace psu, see if it still happens.

Mind you, I'm not convinced by the prices quoted. Bearing in mind that I need a silent psu (I use the machine for music and stuff), I'm looking at about £80 ($150) for a silent 400 watt psu. The first one I blew was under warranty, and I got a returns number, but then moved house and forgot about it. Doh.

Cheers,
Rat.

[evildave]

http://www.turboled.com/product.aspx?catID=119&lastcatID=117&family=83

Two 400 Watt power supplies on this site, DELIVERED TO YOUR DOOR for around $12.00. You'd have to find a UK equivalent to 'Pricewatch' to get similar price search.

Go to http://www.pricewatch.com/ and type "power supply" if you don't believe me.

Of course, if you've kept everything, but haven't already replaced the PS CABLE yet, you're just being silly. Those can get frayed inside and wear out, too.

Mind you, any power supply can be "silent", if you don't mind engineering your own cooling for it (such as by putting a variable speed fan into it yourself).

Any computer can be "silent" if you put it in a sound dampened box, or put it into another room and run the keyboard, mouse and monitor cables in through a small hole in the wall.

Do you have some of those fiberglass shipping boxes full of foam? You can probably get one on ebay cheap. Cut a couple of air holes in it and stick the chassis in side. Baffle the air channels through the foam so there is no straight path from the fans. Once inside a big box, there's no need to close the chassis up. Add one BIG, SLOW fan to move the air around, and some cardboard air channels in front of it to direct air where it needs to go. Put as many chattering hard disks in as you like.

[Wudang]

Have you looked at Novatech - they do a quiet 400W PSU kit for £49. www.novatech.co.uk.
Also worth checking cclcomputers.co.uk and ebuyer.co.uk.

[Riddick]

the poor bugger bought a pc with a fuse --- unfortunate.

laff, i just had to use "bugger" in a sentence, cause i know it's a uk thing.

let this be a lesson --- do not buy a pc with a fuse.

[Skeptoid]

Sod off, Riddick. The poor bugger's fuse is in the power cord, just like nearly all corded appliances sold in the UK.