• 16-year-old killed by unplugged PSU while fixing family PC
    193 replies, posted
Darwin award anyone?
[QUOTE=P1X3L N1NJA;37994960] Im quite suprised how many replies I'm seeing of people actually taking these things apart, they're just not worth it.[/QUOTE] ...but it is worth it. 90% of the time they fail because one component overheats. This is caused by either A: Dust buildup, B: Fan failure, or C: Fan failure due to dust buildup. Cracking it open and cleaning it out every 9-12 months will ensure a good power supply lasts decades. Hell, regularly cleaning it can make a really shitty $25 750W unit last a few years, even the crummy ones will get a lifespan increase worth the effort of popping the top and dusting them thoroughly. So yes, it is worth opening them up. If you have even the slightest desire to see your power supply live a long life you'll educate yourself on how to do so safely and pop the top for cleaning on a regular basis. It's how I've kept mine running for six years now, when normally it would have been discarded in three. Repair, not replace. A $10 fan every three years has saved me from spending $1,000 on computer parts these past few years. [QUOTE=Chryseus;37998320]It's not particularly difficult to repair ATX supplies, the problem usually is quite obvious and 90% of the time is due to bad capacitor(s) rather than anything else. Also some people here like myself are actually electrical engineers or at least know what they're doing. Electricity is perfectly safe as long as your know how to work around it.[/QUOTE] Most of the ones I've pulled apart failed because dust overheated something or caused the fan to fail. I've had to replace the fan in mine twice now, dust got in the bearings and siezed it right up both times. Since I clean mine every 9-12 months I noticed before the PSU itself failed and swapped in a new fan post-haste. [editline]12th October 2012[/editline] [QUOTE=Lomme;37994607] Still, i won't touch those cheap pieces of shit anymore, better invest in something at least decent :v:[/QUOTE] While I wholeheartedly agree with this sentiment, there is still something to regularly popping the top and dusting them thoroughly. Blowing in compressed air through the vents, even from a 90PSI 7CFM air compressor intended for power tools, is not sufficient to clean everything. It's better than not cleaning it at all, but you still end up with dust building up on vital parts, and that dust will eventually cause something to fail. I bought a reliable unit and I clean it every 9-12 months with Q-tips and rubbing alcohol. It has lasted me six years now and it's still rock solid, taking a beating and keeping right on.
Totally unrelated to a PSU/Part shocking you but I was somehow shocked by the power button on my 80gb fat ps3 the first time I plugged it in. Shit scared me so badly oh god:tinfoil:
[QUOTE=TestECull;38009757]...but it is worth it. 90% of the time they fail because one component overheats. This is caused by either A: Dust buildup, B: Fan failure, or C: Fan failure due to dust buildup. Cracking it open and cleaning it out every 9-12 months will ensure a good power supply lasts decades. Hell, regularly cleaning it can make a really shitty $25 750W unit last a few years, even the crummy ones will get a lifespan increase worth the effort of popping the top and dusting them thoroughly. So yes, it is worth opening them up. If you have even the slightest desire to see your power supply live a long life you'll educate yourself on how to do so safely and pop the top for cleaning on a regular basis. It's how I've kept mine running for six years now, when normally it would have been discarded in three. Repair, not replace. A $10 fan every three years has saved me from spending $1,000 on computer parts these past few years. Most of the ones I've pulled apart failed because dust overheated something or caused the fan to fail. I've had to replace the fan in mine twice now, dust got in the bearings and siezed it right up both times. Since I clean mine every 9-12 months I noticed before the PSU itself failed and swapped in a new fan post-haste. [editline]12th October 2012[/editline] While I wholeheartedly agree with this sentiment, there is still something to regularly popping the top and dusting them thoroughly. Blowing in compressed air through the vents, even from a 90PSI 7CFM air compressor intended for power tools, is not sufficient to clean everything. It's better than not cleaning it at all, but you still end up with dust building up on vital parts, and that dust will eventually cause something to fail. I bought a reliable unit and I clean it every 9-12 months with Q-tips and rubbing alcohol. It has lasted me six years now and it's still rock solid, taking a beating and keeping right on.[/QUOTE] Modern power supplies and their 120mm+ fans have that large opening which allows you to blow out say 95% of the dust with an air compressor. That's how I cleaned a Zalman 1000-HP PSU and it hardly had a trace of dust in it after 5 years of operation. I used one of those upright air compressors at around 60PSI and blew the whole thing out very few months, working back and forth between in the intake and exhaust side.
[QUOTE=No_Excuses;38011091]Modern power supplies and their 120mm+ fans have that large opening which allows you to blow out say 95% of the dust with an air compressor. That's how I cleaned a Zalman 1000-HP PSU and it hardly had a trace of dust in it after 5 years of operation. I used one of those upright air compressors at around 60PSI and blew the whole thing out very few months, working back and forth between in the intake and exhaust side.[/QUOTE] That's one model. I've taken apart hundreds over the years and never once did I find one that got completely blown out that way. There was always dust between some of the smaller components, under the heatsinks, on the rectifiers, that sort of thing. That certainly is the case with the unit I have now, it has a 120mm fan opening but blowing it out doesn't get it properly clean. I pop the top and Q-tip that bitch every year or so. It's great yours does but I've never run into one that did personally.
[QUOTE=Chryseus;38001624]Around 20mA through the heart is the threshold for ventricular fibrillation (less for AC), as for time 1 second is more than enough, you only need to interrupt the cardiac cycle for a very brief time to upset the rhythm, the reason devices such as tasers are not usually lethal is because the conductors are close together, lethal shocks are nearly always caused from arm to arm or lesser arm to leg shocks.[/QUOTE] You really have no idea what you're talking about. 20mA through the heart is impossible in this context due to tissue resistance, and I have no idea where you're pulling that figure from because we have only tried direct-to-heart testing on inducted fibrillation on pigs. Moreover, Taser lethality has absolutely nothing to do with their hitting the heart or not. [QUOTE=http://www.aele.org/law/Piskura_Taser_Zipes_exclusion.pdf]...there is not a single piece of medical, scientific, electrical, or engineering peer-reviewed literature, learned treatise, or statement from a professional association finding that an ECD causes cardiac capture, cardiac arrest, cardiac dysrhythmia, ventricular tachycardia, ventricular fibrillation ("VF"), or lethal cardiac consequences in humans. Indeed, human research studies on potential ECD effects are extensive and have never produced VF or lethal cardiac consequence, [B]despite probe vectors across the heart and continuous delivered ECD discharge durations up to 45 seconds.[/B][/QUOTE] [URL="https://www.ncbi.nlm.nih.gov/pubmed/18812645"]This instantaneous shit only comes into play when you're hitting the heart directly with AC peaking around 2A.[/URL] [QUOTE=Chryseus;38001624]Capacitors [b]store[/b] charge this takes [b]time[/b] to discharge so no it's not a transient event unless your practically shorting it out, the actual discharge time can be calculated using simple RC time constants, one RC constant when discharging is equivalent to a drop in voltage of 37%, assuming 350V one RC constant will equal 221V.[/QUOTE] It's a transient by definition, you nimrod. The current is diminished exponentially. Read a book. [IMG]http://online.cctt.org/physicslab/content/phyapc/lessonnotes/capacitorcircuits/smcurrentdecay.gif[/IMG] [QUOTE=Chryseus;38001624]Assuming my body resistance is 10k and a 100uF cap that will give a peak curret of 35mA, after one time constant which is (T = RC) 1 second the current will be 22.1mA.[/QUOTE] [URL="http://hyperphysics.phy-astr.gsu.edu/hbase/electric/shock.html#c3"]And 35mA is not going to do any more than freak you out to begin with.[/URL] You're only in danger assuming peak is much higher. [QUOTE=Chryseus;38001624]I've experienced both AC and DC shocks numerous times so I can assure you I can fully tell when I am being shocked, and I did actually measure that cap after it shocked me, it was around 170V definitely not a transient event.[/QUOTE] [QUOTE=Chryseus;37988013]I once shocked myself with cap charged to 350V at 100uF, it barely dropped 50V after giving me a very nasty shock.[/QUOTE] Pick a story and stick with it. [QUOTE=Chryseus;38001624]Oh and don't even try to go into detail when it comes to body resistance, it can vary dramatically depending on many variables, once your being shocked and the skin is breached it can drop significantly making things much worse.[/QUOTE] The broad spectrum is known, and there aren't going to be punctures coming from the leads of a capacitor.
[QUOTE=Xenocidebot;38024154] Pick a story and stick with it. [/QUOTE] I don't think he's arguing that the near instantaneous discharge of a capacitor isn't transient, but that the event where a loaded capacitor is discharged is no longer transient, and more of a charge decay. Technically filter capacitors like these shouldn't have anything but transient current changes, but when they're used in a situation like this such that the capacitor is used like a low ESR battery; I can't see how this would still be labelled as transient. Actually never mind, I'll leave the above text there but I understand what you're saying. The discharge itself is a transient event, wherein the discharge may or may not equal the capacitance.
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