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Computers Breeding Harmful Fungus 70

Soft writes: "The BBC has a story on several kinds of fungus proliferating among the dust inside computers. Not quite Dust Puppies, but hospitals are worried about the computers they use, especially in intensive care units." So besides monitor burn, eyestrain, electrical shock, carpal tunnel syndrome, short attention span and lifting-related injuries, now you can worry about Aspergillus fumigatus, too. (Or occasionally disinfect.)
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Computers Breeding Harmful Fungus

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  • .... and I thought that floaty feeling was just from playing Counter Strike too long..

  • You have to wonder what kind of computer placement and usage habits they have to have developed such a problem. I have never seen an "exhaust" coming from my computer's fans. I'm going to (probably incorrectly) assume that they are probably storing their computers in a not so healthy way... maybe they're too crowded or something, too close to those bio-hazard boxes hospitals use for refuse. It's more likely that the computers picked up a fungus or two from the patients and just became a home for it, than started growing it on their own.... improper care by the hospital attendants kept the fungus alive. I just wanna know, though: how does a fungus grow in a computer? Sure, it's dark and hot, but there's not much moisture in there, and not much organic matter for the fungus to consume, except maybe the small amount of dead skin cells and so forth in dust. Ew!
  • by dj28 ( 212815 )
    I guess you could say that all computers have bugs in them ;)
  • by Jonathunder ( 105885 ) on Saturday May 26, 2001 @04:07AM (#197070) Homepage
    For those wondering what in the Heck the "the as-washrooms-are-to-bolsheviks dept." reference is about, it was a 1920's advertisement [] by the Scott Paper Company, warning if your company restrooms didn't have the right paper towels, you may be fostering Communism among your employees. Really.
  • Since notebooks and flatscreens have less space, fewer vents, and in many cases no fan at all, would fungus be less likely to grow in them?
  • by Chas ( 5144 ) on Saturday May 26, 2001 @04:14AM (#197072) Homepage Journal

    Something a lot of people outside the health institutions don't hear much about.

    Nosocomial Infections

    Basic Translation: Hospital-Acquired Infections (you get sick from stuff you didn't have before you came into the hospital).

    It's really not surprising that relatively warm, dark environments like computer cases are breeding grounds for this sort of thing. Heck, you have people going into and out of infected rooms, picking stuff up, mixing it about on keyboards, touch-screens, etc. Computers are already an avenue of infection simply due to their high traffic usage.

    I work on an orthopaedic/trauma/general surgery unit at my institution. You name it, we've seen it. There's so much stuff (disease-causing organisms) coming in, that most people barely notice if they pick up "a little something else".

    Consequently, we spend a LOT of time making sure rooms are clean and surgical patients are kept as far as feasibly possible from infected patients.

    Chas - The one, the only.
    THANK GOD!!!

  • I anticipate a growing market for nice hot vacuum tube computers...
  • by Alik ( 81811 ) on Saturday May 26, 2001 @04:17AM (#197074)
    Aspergillus is a favorite fungus for my profs to test, because the second your immune system goes away, it just waltzes in and starts invading everything it can find. However, one of the things I recall being taught is that part of the reason we have troubles with it is that it's literally *everywhere*. I'd be willing to bet money that it was in the ICU dust beforehand, just due to all the incredibly sick patients (some of whom had invasive aspergillosis) that had come through. It's the same reason the antibiotic-resistant bugs live in hospitals --- we can't get rid of them.

    Oh, and for everyone else worried about Aspergillus from their computers: quit it. Unless you've lost a seriously large chunk of your immune system to chemotherapy, AIDS, leukemia, or something similar, the worst Aspergillus can do to you is trigger your mold allergies. When something is everywhere, the body learns to deal with it.
  • Sounds almost as good as Microsoft saying that Linux is communism!
  • by IronicCheese ( 412484 ) on Saturday May 26, 2001 @04:25AM (#197076)
    When something is everywhere, the body learns to deal with it.

    Are you sure about that? I mean, MSFT is everywhere and...oh, nevermind.
  • Well, you know, I've been *trying* to get them to put "Windows-induced psychosis" into the DSM-V, but for some reason all their eyes glaze over and they chant "Bill-is-good-all-hail-Bill".
  • by xx01dk ( 191137 ) on Saturday May 26, 2001 @04:54AM (#197078)

    Just reminded me of the time I was tasked with finding out why my boss's keyboard didn't work any more.

    There was literally a hardened crust of fried chicken skin, hair, grease, coffee grinds (and probably coffee), cola, nail clippings, and various other unidentified biological stuff. Sounds like the perfect breeding ground for anything that likes to grow in warm, dark, sticky places.

    Of course, this was the guy everyone feared because of his projectile spittle, so it was probably not unreasonable to be able to find remnants of his meals inside everything at his desk, including his computer. Glad I don't work there anymore.

  • I recall seeing pictures, etc of direct emmersion of running electronics in things like freon. Things like TVs, etc

    If you want a very technical discussion the article here [] covers it nicely.

    Simply put, full immersion would handle the problem because the fungus would not grow under those conditions. Of course, other factors may make this inconvenient.

    OverClockers would likely find the magazine where the article comes from, Electronics Cooling [], interesting to read as well.

    Check out the Vinny the Vampire [] comic strip

  • Computers clearly are dangerous for everybody. Small children should be kept away from them. They will kill you before you even realize it. You should wear a combination gas mask/radiation suit when within 50 feet of one. Computers are polluting the environment too through our landfills.

    They must be stopped!

    P.S. I hope you realize that's sarcasm.

  • ..would be to get [] a [] clear [] case [] for your computer, so you can at least keep an eye out and know when the fungus appears :)
  • Except, these computers are in ICUs, which means they are near patients who are already fighting to stay alive.

    Yes, I know we are talking about the dust inside the computers, but particles this tiny go everywhere, especially if there is any contact between the person using the computer and the person treating the patient.

    Ever been in an ICU? It is a scary place to be. Nobody there needs extra heath problems to worry about.

  • Open up a machine that's been running in even a slightly dusty office building for a few years, and you'll find plenty of dust. Certainly enough to grow a nice colony of fungus on. As for moisture, there is an awful lot in the air, you know. Many microorganisms can survive, and thrive, with just this as a resource.
  • You're missing my point. The fungus is *already* in the ICU. It's already being blown around by the ventilation system. Sure, you can reduce risk a little by not having your computer fans kicking dust right into the patient's face. However, blaming the machines for the presence of the fungus is just plain wrong.

    Are there things on the computer keyboard? Yes. And also on the sheets. And on the equipment. And on the countertops. And being tracked in from the outside with each new patient. You can't sterilize the ICU, at least not yet. No matter what you do, any surface that isn't either fresh from the autoclave or inside a sterile wrapper is automatically contaminated. Now, maybe those antibacterial surfaces we've read about will cut this down eventually, but for now, the only solution is careful monitoring of patients.

    (And for the record, yes. I'm a med student. I've never been in the ICU as a patient, but I've been there several times as staff/observer.)
  • Those fsking things run hot enough to cauterize a severed limb. It's like having your own personal autoclave. Few fungi can survive 400 degree temperatures.
  • by wowbagger ( 69688 ) on Saturday May 26, 2001 @05:45AM (#197086) Homepage Journal
    This is why you should clean you machines once in a while: shut them down (quitcherbitchn about your uptime - it's not a contest!), open the case, and either vacuum (with non-static generating vacuum) or blow (again, with a non-static generating air source) the dust out. Clean the power supply (the 300VDC on the main caps will tend to attract dust) very carefully. Ditto for the monitor: the 27KV anode will pull dust out of the air like a magnet pulls iron filings. (You should see some of the machines I've seen in machine shops/auto garages/printing shops.... Gak!)

    Not only will you prevent allergies, you'll keep your system running cooler, help prevent you power supply from sparking out, and have a good chance to check all your fans to see if any are about to fail.

    If you are really hard-core, you'll put filters on all intake fans, run positive pressure (i.e. fans blowing in, and air exiting via slots/holes etc.) and clean the filters once a month.

    And DON'T SMOKE NEAR YOUR MACHINE! You've no real association for the word "disgusting" until you've worked on a monitor that was used by a smoker. I've seen some monitors that I 'm surprised didn't die of cancer of the CRT, they had so much tar and nicotine on the bottle. You can go through an entire bottle of 99% isopropyl alchohol (DON'T use regular rubbing alcohol, it is 30% water!) and still not get all the gook off.

    A clean machine is a happy machine.
  • Fungi like dark, warm, environments, no? What if a small fluorescent light were installed in the cases? Perhaps that would help keep the growth down. Or maybe an ultraviolet light? UV is sometimes used to sterilize drinking water and is known to alter the DNA of fungi, bacteria, viruses to keep them from reproducing. There's a chart of how much UV is required to kill certain organisms at [].

    Most computer manufacturers who sell large quantities to hospitals and other health-care facilities would probably be willing to install these.
  • by Waffle Iron ( 339739 ) on Saturday May 26, 2001 @06:03AM (#197088)
    And DON'T SMOKE NEAR YOUR MACHINE! You've no real association for the word "disgusting" until you've worked on a monitor that was used by a smoker. I've seen some monitors that I 'm surprised didn't die of cancer of the CRT, they had so much tar and nicotine on the bottle. You can go through an entire bottle of 99% isopropyl alchohol (DON'T use regular rubbing alcohol, it is 30% water!) and still not get all the gook off.

    Here's some more important advice: DON'T SMOKE NEAR YOUR LUNGS! You can't swab them out with alchohol. Same goes for your coworkers' lungs.

  • I recall seeing something, some polymer coating I believe, that prevents bacteria from growing on anything that has the coating. Anyone have a link?
    3 S.E.A.S - Virtual Interaction Configuration (VIC) - VISION OF VISIONS!
  • So that's what happened to the Mir fungus!
  • You don't think there are any lurking variables here? Like the techies that came in with the computers to install them into the hospital? It seems to me that they could offer the same influx of new germs into the environment that a few boxes of metal and plastic could, except that these boxes of metal and plastic generally aren't known to produce, uhh, biohazards.

    I'm sorry, but this just doesn't seem right to me. If I were in the hospital, hazard or not, I would rather have a computer in the room and a flatscreen above me so that I may cruise the net while I lie helpless.

  • A warning for you fungus out there: don't grow in computers! You know what heppened to the Mir! It can happen to you too!
  • is this the beginings of a new nemises for the dust puppy? Since the crud puppy seems to be long gone.
  • It's been a while since I've studied history, but this should be something approaching the truth:

    The bolsheviks were a political, not a racial group. In the original days of the russian Commumist party under Lenin, there was a divide between the 'bolsheviks' and the 'mensheviks' over various policies. The bolsheviks rose to the ascendent, and the mensheviks (I think) were variously expelled, imprisoned or executed depending on how much of a nuisance they made of themselves. The 'bolsheviks' then essentially became the Communist party in Russia, & so the early Russian strain of Communism became known as Bolshevism.

  • Gee.. computers already contain three deadly elements, including lead.
  • I'm sorry, after reading through this again, I've realised that I forgot to mention that by 'early days' I meant just prior to the Revolution - I think that the Mensheviks were thrown out prior to the Communist's rise to power, although their name (given after the event, meaning 'of the minority' compared to 'bolshevik' meaning 'of the majority') continued to be employed for years afterwards as a phantom enemy to keep the people in line (read 'Animal Farm'). Stalin later used the same tactic with his talk of 'Trotskyists' etc.

  • I just looked inside my baby and found that the healthy green glow I've been seeing at night is indeed a giant 'shroom, and not an LED as I suspected. At least it's not as bad as the nasty mutating fungus that was devouring Mir and is probably starting to take a hold on the ISS. BTW, does anyone know if this stuff is actually dangerous to healthy people?
  • I spend all my time debugging software, and I start worrying about my hardware too?

    If I'm lucky, when I'm finished debugging the computer, and throw it over the wall, maybe I'll hit a QA person or two.

    I'm thinking the monitor might need some debugging too.

  • by Technician ( 215283 ) on Saturday May 26, 2001 @08:22AM (#197099)
    I wonder if one of the custom case jobs could be modified just for this. Instead of fancy Neon in the case, put in a germicidal short wave UV lamp. Don't forget to add the charcoal filter over the power supply fan for the ozone.
  • I noticed I have a slight dust allergy, so I went and spend $50 on an air cleaner from Sears. It works great! Now, I just wish they'd combine an air cleaner and a humidifier into the same unit. THere's lot's more than fungus to worry about. Dust mites, pollen, soot, insects alive & dead - all can be bad for you. I also read somewhere than there's a fair amount of radioactivity in common dust. I have yet to take a geiger counter to my dust filter or vacuum cleaner bag, but if anyone has a counter, I'd be interested in hearing the results it they did.
  • dont know about fungus, but i got three spiders roaming all over my pc case, preferring the back just below the smps vent. they seem to re make their webs every three days. sometimes the web is smaller and designed differently. i couldnt understand what they were eating...but later i saw them trapping a small flying insect which looked like a mossquito. ( several of these fly at night near my place. i didnt disturb the spiders ( web, etc you know )but lately theyve gone away. note a small lizard. ..ok gecko maybe. so he too stays. but i also saw a toad just round the corner , behind the door. any softweare with tha name? else he gets kicked out fast.
  • ...aren't you confusing Dust Bunnies and Hush Puppies?

    (Yes, it is in fact my duty to nitpick.)
  • I doubt it. It isn't the airflow from the fan that causes the fungus, it's dust and warm, moist air passing through the computer. While laptops might pick up a little less dust, they probably would still take up enough to be contaminated. On the other hand, without active exhausts, like fans, laptops might be less likely to spread the fungus outside of the computer's case, even if it were growing inside.

    "Sweet creeping zombie Jesus!"
  • The point of the article was not that the computers are bringing in new germs or fungus. The fungus existed in the ICU before, carried in by patients and the like. However, patients leave, and most areas of hospitals are regularly scrubbed down with anti-bacterial and anti-fungal products. But if places aren't cleaning the inside of their cases, there is a nice safe haven for fungus and bacteria, which is almost immediately re-introduced into the environment by the exhaust fans of the computer.

    "Sweet creeping zombie Jesus!"
  • American researchers found a rare hospital fungus "Aspergillus fumigatus" in their intensive care wards following the installation of computers. Dr Forstall said the fungal contaminations were first discovered when the computers were introduced into his hospital's 23-bed Intensive Care Unit (ICU).

    I'm a medical student and have done some rounds with the doctor incharge of microorganisms at our hospital, so I can say fairly confidently that they were testing for the stuff long before the computers arrived. Granted, I'm in the US, but culturing for bacteria is not that expensive. The article says the fungus was found in the wards after the introduction of the computers. Assuming they've been tesing all along, which I'm bet there were, I think its fair to say the computers were a reservior for the bugs.

    You are right, Aspergillus is everywhere in the environment, and probably is occasionaly introduced to IC units in other ways, but those places are cleaned reguarly and bed sheets are more often thrown away and burned rather than reused. So I'm sure it gets introduced other ways occasionally, but once the source leaves or is cleaned, its gone. Now the computers on the otherhand it seems were overlooked as a source and provided a regular source of contamination which to a patient lacking a cell mediated type of immunity (ie. AIDS, organ transplant patients) can be deadly.

    Like you said, though, no one healthy would have to worry about this unless you started licking your computer clean! Aspergillus is known to produce a toxin called aflatoxin, which can cause liver damage and liver cancer. Normally this is only seen in areas of Africa south of the Sahara desert where the mold tends to grow on there food before it is eaten.

  • This seems to be yet another argument against cooling fans in computers...
    Am I glad that I'm working with a fan-less computer!?!
  • or perhaps the greasy IT admins. If I were this hosptial, I'd look into the hygenic habits of the IT staff first.
  • aren't you confusing Dust Bunnies and Hush Puppies?

    Have you ever read the User Friendly [] comic strip? Dust Puppy is the mascot of UF.

  • How do you clean a power supply safely? I do not want to open it for obvious reasons. They are kind of expensive to replace though when they are clogged with dust. ALso you should never open a monitor unless you had lots of training. A television stores over 20,000 volts of electricity. THis is why the old televions took 2 or 3 mins, for the screen to pop up. They just just amplified the power in teh coil into it was high enough and then shot the electron gun in the tube. Todays monitors I assume use the same principle but the screen pops up faster because the monitor stores the electicity internally.

    Even if its not on!

    Anyway my p166 died a few months ago due to dust in the power supply. I want to revive it but paying alot of money for a new power supply on a pos obselete computer does not make much economical sense. If I could just get the dust out and replace the fan myself, I would have it made. I think I will play conservatively on this issue.

  • Power supplys aren't that expensive...a brand new ATX 300W power supply runs about $60 I think---an older one for a P166 should be much cheaper.

    -Julius X
  • If the computer case is the source of the problem, then the case shouldn't be in the ICU patient area. There are a number of off-the-shelf products for moving a monitor, keyboard, and mouse far, far away from the system unit.

    So you put the PC cases in a machine closet (with proper AC separate from the ICU AC to keep the machines running cool) and run the KVM extender to a convenient point to the bed in the ICU.

    Or use Unix in a closet and run VT-100 terminals...

  • My rat seems to have a perverse taste for thin copper wires. I had stored my old computer in my bedroom corner for a while, with one front panel missing. When I opened it for turning it into a web server, I found a pile of chopped wire from the bottom: cgi/ratputer.ser?height=768 [] and cgi/ratputer.ser?current=1&height=768 []

    Luckily, I had to replace just the ground wire and the IDE cable, as most other wires are useless anyways (who needs a reset button?). Also the processor's cooler fan wire was cut, but I couldn't figure where it should be connected. Luckily, the processor runs very cool without it, so I guess the cooler is there just to give an impression of a powerful processor?

    (The computer in the pictures is now the web server serving the pictures, so please don't slashdot the poor old non-cooled processor too much... )

  • by wowbagger ( 69688 ) on Saturday May 26, 2001 @12:47PM (#197113) Homepage Journal
    The simplest way it to take the power supply outside, and using a source of compressed air blow the dust out.

    However, use a source of clean, dry air: don't just go down to your local gas station and use the air for airing up your tires - it frequently has lots of water in it. (when filling your tires, it's a good idea to bleed some air from the air line, and if you see mist, go elsewhere.)

    Opening a power supply is really no big deal. The capacitors in the power supply will have bleeder resistors that will pull the charge off them when the power supply is turned off. Just undo the case of the power supply and air it out.

    As for a monitor: again, not a big deal. You're not going to be reaching around inside the thing, just hosing it out with compressed air. Don't worry about the charge on the bottle: again, modern monitors have a bleeder resistor that drains the charge off in a few minuts.

    Also, the warm up time of an old monitor had nothing to do with "amplifying the power in the coil" - the delay was in heating up the filaments in the tubes used to power the monitor. Until they were hot enough to emit electrons the tubes didn't work. Modern monitors don't use tubes, save for the bottle, and the time for the CRT's filament to heat up is only a few seconds.

    However, if you don't feel comfortable opening up your monitor or power supply, then don't. You are the best judge of what you can or cannot do. However, I wouldn't (and don't) worry about it. Just make sure to unplug things when you are working on them.
  • I was just thinking of something similar, except the irradiation would be SW controlled, to zap the organisms for 30 seconds or so.
  • > YOUR LUNGS! You can't swab them out with alchohol.

    I bet some people do..

    Rather appropriately to the story - just as I was writing this, a big spider landed on my shoulder. As if I wasn't deep enough on the web already.


  • The primary symptom of Microsoft-induced psychosis is the belief that "computers are unstable and must crash often".
  • It probably didn't help that the moisture level is probably higher in a hospital than in an office, thus the fungus had more water than in most an office. Particularly in an ICU, the humidity level would be kept high enough to reduce breathing irritation. Some ICU patients would be on various respiratory devices which provide humid air. And those smooth floors are cleaned regularly with mops.
  • "UV is sometimes used to sterilize drinking water and is known to alter the DNA of fungi, bacteria, viruses to keep them from reproducing."

    And induce skin cancer in human beings. If you're using enough UV to kill a microorganism, you're using more than enough to cause nasty sunburns and eventually, tumors.

    Not that this has to happen, of course, but I wouldn't go putting a short-wave UV lamp in any conventional computer case, what with all their openings, and their tendency to be placed under desks (near legs)...
  • No, I don't ready UF. UF is fucking stupid.
  • That reminds me of a place I worked. It was a software company that produced restaurant software. One of the biggest customers was Burger King. After rolling out the product to 500 stores, I worked in support. The Burger King employees would call in with software and hardware issues.

    After calling in a ticket for a tech to go to a store that was having network issues, I got a screaming tech on the phone. He said that he wouldn't go back to that store, as he had already replaced the network cabling 3 times. Every time he went out, rats had chewed through the cables (and this was coaxial 10base2).

    From the rollout, I saw what can happen to a computer in a hostile environment. Fun things like:

    • A film of grease 1/16" to 1/8" thick on all components.
    • A box cutter stuck in the floppy drive.
    • keyboards so covered in grime that you needed to wash your hands after using them (we actually installed plastic covers on the new keyboards).
    • keys that wouldn't return do to the inordinate amount of softdrinks spilled on them.
    • cabling scorched by frying equipment.
    So, I can imagine that a computer that is exposed to germs rather than grease could build interesting things. I'll have to remember that the next time I take a consulting gig for the medical industry.

  • Yep, except you are forgetting that all the whirring, humming equipment that are keeping patients in the ICU alive have....wait for it....wait...wait....FANS in them.

    Oh my god.

    I happen to know this doctor - as a matter of fact I installed 90% of the computers in our little Flint, MI Corporate Super Power's patient rooms. I headed up the project.

    This guy was a major pain in my ass, and for no good reason. Infection rates in ICU's spike and drop like the weather. The pattern is totally chaotic, but more than anything it is usually related to the overall health of the healthcare providers that are working on the patient. In addition to their general hygiene.

    Additionally, to those who had wondered - no cultures were not taken before the pc's went in. What would they be taking the culture samples from? There wasn't a pc there to swab! The infection rates spiked quickly after the PC's went in, and the medical staff went on a rampage trying to associate the two. Since then the levels have died right back down to normal.

    Of course, it could have something to do with one of my techs testing positive for exposure to TB after the project was over.

  • More people are spending more time at their computers. I eat infront of mine all the time. I know someone who has put their keyboard throught the dishwasher because it collects food and all sorts of stuff that can't just be blown out. I got this old 486 from a government office and I was actually afraid to type on the keyboard. I took it out side and shook it out, it was full of hair and dirt. I'd be more worried about stuff growing in there than in the case, especially because we touch the keyboard everyday.
  • If I open up my old 286-based notebook, I'm gunna get legionaire's disease! Yeah right, AOL 3.0 floppies collection is gathering more dust & is definitely mouldier than the inside of that old hardware ever will. Read the main article again. They are most concerned of use in hospitals, where evil flesh eating fungi could end up in you chest cavity... Well anyways, don't take me seriously. I sure don't.
  • And they think computing is a safe hobby ;-)
  • When I was in high school the computers there were dusty to a level you cannot believe (unless you are a tried and true geek, then I suppose you could...)

    I had a 286 begin to smoke, and spark, then it died, all because of the dust inside.

    Worse, a IBM PC Junior I was using caught fire because of the amount of dust in it. Suffice it to say that system did not survive either. (I unplugged it, not that that helped stop it from burning, it went out on its own once the dust was consumed.)

    To this day whenever a computer crashes anywhere within my vicinity my friends still refer to my "EMP" field that I generate...
    (Yes this supposed "field" has crashed *nix boxen too, but not as often as other OS's)
  • not sure if this is exactly what you mean, but try this []
  • It would be nice if this would work, but UV destabilizes plastic molecules just like viral or fungal DNA. Place some of that shiny neon-colored plastic outdoors this summer and you'll see it fade to a lighter non-neon or clear color and crack. This is even easier to see in video rental stores as all the older title boxes from the 80's are faded to white (the neon-yellow fades to white).
    I work in a injection molding plastic factory and we did neon-orange flashlight cases for a while. The company put the reject cases on the driveway guide posts and these would fade from neon-orange to orange to yellowish to white over the course of a year (and these had a UV-stabilizing compound added to prevent this). Of course, this is symptomatic of all fluorescent materials.
    The best method to de-germ hospital PCs would be to add a spill-proof keyboard cover (less chance of hair & skin cells entering the keyboard to grow mold and could be washed and replaced regularly). The charcoal filter over the air exhaust is a good idea (though ozone does kill germs and also chews up organic materials).
    A quick Google search for "sterile computers" gets me an industrial link
    (not exactly ergonomic, but dust-proof)
  • Actually...

    Aflatoxin is found everywhere. Harvested peanuts are a common source, but it is also found on corn and cottonseed as well. It just needs the right conditions of humidity and organic matter.
  • A UV lamp inside your computer would do wonders for your EPROMs. Like, erase them all...

  • Just make sure to unplug things when you are working on them.
    Um... unplugging the monitor doesn't discharge everything inside it. There's still enough charge to kill you, hours afterwards. Don't play with high voltage unless it's your job.

  • Metal tabs over the windows takes care of that. Most computers are no longer using EPROMS they are using flash or EEPROMS
  • Not quite true: read the post again. All modern electronics have bleeder resistors to bleed the charge off the caps for that very reason - so techs don't get shocked.

    Secondly, the only thing in a monitor that has anywhere near the charge to kill you is the power supply. The bottle may be charged to very high voltage, but the source impedance is very high. Look at it like this: the bottle sinks about 200-300 watts of power, at 26KVDC or thereabouts. P=VI so I=P/V, so I = 300 Watts/ 26000 V = 11.5 mA, or enough to be felt and that's about it. You need about .1A to kill. And that's assuming the high voltage supply is running. If all you are getting zapped by is the capacitance of the bottle, you will have much less current, and that only for a few milliseconds. The greater risk of damage is from you flinching and hurting yourself.

    Now, the power supply, that's a different animal. You have about 300W of power at 300VDC (the first thing any modern power supply does is rectify the AC line voltage to DC). That's 1A of current, more than enough to kill you. Furthur, that's being fed into about 50-100 uF of capacitance, and that will store enough charge to hurt you. Except that the caps in the power supply have 1Mohm bleeder resistors on them, and will drain down within a few seconds of being turned off. The only danger there is if you remove the bleeders - then dielectric recovery will allow the caps to charge back up.

    However, IF you don't remove the bleeders, IF you let the monitor have enough time to bleed down, IF you unplug the damn thing before you work, you will be fine.

    NOTE: I'm directing this toward cleaning the monitor. You don't need to turn the thing on to clean it. Troubleshooting it is a different matter, since you will have to turn it on to do so. If you are troubleshooting it, then you need to follow all the HV precautions: don't work alone, keep one hand in your pocket (so if you do get bit, the current won't go through your chest, thus reducing the risk of inducing ventricular fibrillation), and use appropriate tools. However, if you have the needed skills to be troubleshooting a monitor, you should already know this, and not need me to tell you.

    Trust me, I've worked with everything from 440VAC three-phase power to 40KV laser pulse drive systems to 2KW microwave systems. I'm still here.
  • I've always heard that it only takes 10mA through the heart to kill, so by your calcs it could be dangerous. A quick search didn't turn anything up that would support either claim.

    Without lots of knowledge and a little experience, high voltage can be tricky.

    In the end though, I'd tend to agree, your monitor's tube is probably only going to give you a good zap, chances are you'll live to tell the story.

    Chris Cothrun
    Curator of Chaos

  • Correct: 10 mA through the heart will induce v-fib, however if you are getting zapped through your hand, the current will spread out throughout the torso, and to get a current density high enough to put 10mA through the heart, you'll have to dump at least 100mA total current. Visualize it like this: for any given path, your heart takes up less than 10% of the total cross-sectional area of the chest.
  • Wow, I never cease to be amazed by peoples tendency to panic and not think things through.
    What conventional computer case is going to let the UV light escape and shine directly onto someone's legs?
    And I think that in the unlikely case where some moron positioned it so that it did shine on someone, say through an open port in the back, AND they were wearing shorts then they would probably notice a strange tanline before they got cancer.

    There are a limited number of IQ points in this world, and the population is rising.
  • Q: why do you think it needs humidity and organic matter?

    A: Because those are the conditions perfect for Aspergillus. Aflatoxin is a toxin, not an organism. It is produced by an organism, and to my knowledge the only one that does is Aspergillus

Who goeth a-borrowing goeth a-sorrowing. -- Thomas Tusser