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Handhelds Hardware

A Hidden Threat To Handhelds 214

Posted by michael
from the shocked-through-the-heart-and-you're-to-blame dept.
Logic Bomb writes: "An article from the San Francisco Chronicle focuses on a lawsuit against Palm, but talks about a larger issue: static and handheld computers. Basically, as computing equipment becomes smaller and more likely to be carried around, major damage from static becomes a serious threat. As the blurb at the end of the article says, it takes 3500 volts for a human to feel a shock, but only 200 to potentially scramble a microchip." We already mentioned the lawsuit, but this has more information about the supposed risks to your motherboard.
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A Hidden Threat To Handhelds

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  • ..of blatant negligence on Palm's part, or a case of corporate stupidity, or a little of both?

    If they prove that Palm knowingly sent out these devices knowing they could toast h/w, then unleash the hounds...but if it was a simple oversight (which is highly unlikely), well thats where things get interesting....

    personally, i think we're getting a little too sue happy these days...
    • Getting to be too sue happy? As in, has not been too sue happy before? ;-)

      I always figured sueing was a national sport in the US. Just after baseball and basketball in popularity.

    • It's unbelievable... There's no doubt that both palm and Motherboard Manufacturers should do better when designing for ESD resistance, but users should be careful rather than sue... but this, I guess is the american way...

      --CTH
      • There's no doubt that both palm and Motherboard Manufacturers should do better when designing for ESD resistance.

        Sure, they could ESD harden the motherboards, but are you willing to pay for the increase in cost?

        Basically Mr. Sue-Happy is gonna raise the price of your computer components. I'd rather have cheaper components than pay for someone elses uneducated electronics bumblings.
      • There's no doubt that both palm and Motherboard Manufacturers should do better when designing for ESD resistance, but users should be careful rather than sue...

        Which is it? Palm/mobo should handle ESD better, or users should be more careful? If the Palm/mobo really should handle ESD better, shouldn't the users sue? How else would the get better ESD handling? If the users really should be more careful, why should Palm/mobos waste money on better ESD handling?

  • Basically, as computing
    equipment becomes smaller and more likely to be
    carried around, major damage from static becomes a
    serious threat.


    So don't stay static and yer safe! Keep on moving boy ;-p~
  • It doesn't matter how small it is. Since It's a Class B computing device it can only radiate a certain amount of emissions (or is that just RF). The user should simply be aware that any electronic device will carry this risk, no matter how small, and by purchasing the device, assumes the risk... No harm no foul...

    A bunch of lawyers just decided that they might be able to make a quick buck here...

    --CTH
    • Class B has nothing to do with static electricity- it is just about intentional and unintentional radiation derived from the normal operation of the electronics.

      I'm not even sure a (single) static discharge would show up on an EMI scan (which is done for class B certification) It would probably show up as a slight increase in the baseline noise level, but not push it beyond the class B limits.
      • That's exactly my point:
        I'm not even sure a (single) static discharge would show up on an EMI scan (which is done for class B certification) It would probably show up as a slight increase in the baseline noise level, but not push it beyond the class B limits.
        /blockquote>While I agree that the specification doesn't specify allowable static discharge, I would consider it a componant of the radiation the device emits...

        --CTH
        • I would consider it a componant of the radiation the device emits...


          But the device isn't emitting it- the person is the source of the static discharge. The static charge is absoulutely *not* generated by the operation of the device- If it was, then I agree that it would have to be taken into account.

          For static discharge, the FCC class rating of the device is a non-issue. It is a concern safety-wise, but the FCC rating is about emissions, not about safety. There are other, separate, certifications about safety.

          I've taken part in EMI testing for class B certification- static discharge is not a part of it.
    • The problem has nothing to do with the FCC certification of the Palm or the user's computer. The FCC is concerned about radiation from electronics devices causing interference to other RF spectrum users, not about the safety or reliability of electronics devices.

      A serial port (RS-232 interface) that can be damaged or destroyed by the static electricity from a user is poorly designed.

      • I agree that the FCC is not specifically concerned with static discharge, although it would probably sho up on the EMI test.

        As for your other point:
        A serial port (RS-232 interface) that can be damaged or destroyed by the static electricity from a user is poorly designed.
        I completely agree, although I believe one of the PC manufacturers who the users claim can be affected by this problem is DELL, which as far as I'm concerned isn't known for their poor design. I would certainly expect them to have sufficiently grounded serial ports.

        --CTH
    • by choco (36913) on Tuesday August 28, 2001 @08:41AM (#2224886) Homepage
      You are confusing ESD (electrostatic discharge) with EMC (electromagnetic compatibility). They are very seperate issues.

      is a serious problem. It IS possible to design interfaces which offer useful resistance. But it is suprisingly hard to design and build in practice and it causes problems throughout the electronics industry. To build a Port (USB, serial, whatever) which can resist electrostic discharges requires that you use most of the following :

      Protective devices which can dissipate the energy. The risetime from Static discharges is very fast and overwhelms all but the best protective devices.

      Drivers/receivers which are hardened against static (the major semi manufacturers who do such chips do now make some - but they tend to cost more

      Careful mechanical design to further reduce the problem - arrange that the "grounds" always touch first - preferably through a few hundred thousand ohms of resistance.

      Optical isolation (although many people fail to understand the limitations of this technique - the stray capacitance between the isolated section and everything else is almost always high enough to allow static damage to happen.

      More importantly manufacturers need to test their designs properly using realistic test models. Much equipment - including from the big name manufacturers pays little or no attention to this issue. Presumably for cost reasons - although if the right measures are "designed in" from the start the premium is going to be pretty small. It's interesting to compare the serial interface from a top branded PC with a functionally-identical interface from some serious telecomms kit.

      I'm an engineer - not a lawyer. But I do know that I'd hate to have to do the finger pointing in the "Palm v motherboards" issue. If forced to comment I'd say that both sides should share the responsibility.
      • Careful mechanical design to further reduce the problem - arrange that the "grounds" always touch first - preferably through a few hundred thousand ohms of resistance.

        Ummm... how the hell is ground to be effective with that kind of impedance? Ground potential should be equal.

        • It's only a "transient" state during the mating process. Once fully mated you want the impedance to be as low as normal.

          But ideally you want the "first touch" to be a high impedance. That dramtically slows down the rise time - which is likely to prevent damage.

          Most likely static "sources" can be effectively discharged to safe levels by a leakage impedance of megohm or so - and within a few ms.
      • You are confusing ESD with EMC

        I just can't keep up. I know about RMS and ESR, but who are these new guys?
    • Of course you have to be careful of static electricity. Anybody who's taken a rudimentary hardware course and paid attention knows that computer hardware is susceptible to static electricity


      Anybody who uses a computer without knowing how it works deserves whatever evil befalls him.

  • by Anonymous Admin (304403) on Tuesday August 28, 2001 @08:28AM (#2224851)
    It must have been my imagination that hurt when I plugged that paperclip into the wall outlet.
    • I think it IS your imagination. AFAIK you need 2 paperclips, 1 in each hole of the outlet to expercience the real hurt. : )
    • The UK phone system uses about 50 volts as a carrier & I got one hell of a belt off of the back of a winmodem the other day.
      • Modems often have line transformers, and these have coils.
        Coils can increase the voltage quite a lot - that's likely to be what happened.

        If you 'charge' a large coil even with a low-voltage battery, and then remove the battery, the coil will try to discharge. Since there is no longer any connection to discharge through, the voltage will increase until it can discharge with a spark (or through leakage currents, whatever comes first).
      • The US is supposedly using 48 volts, but I measured 72.9 on a friend's phone line.

        I also know that in the past, I could touch my phone line posts, no problem. Now they have a ZING to them. Maybe they increased the voltage.

    • Ever tried one of them 9v things on your tongue? I did, plenty, when I was a kid, not quite painfull but you feel it.

      Somehow I also managed to get my tongue stuck on my toy racing track once (which was like 12 or 18v or so).

      THAT HURT!
    • And the amperage also has an effect.
    • Yep. My finger slipped when handling a circuit board in high school electronics class. Got a nice belt of 225V before the circuit breakers blew. Knocked me off my stool onto my ass. I make sure the power is disconnected if I have to do that sort of work now!

      BTW, if you unkink the paper clip, bend it into a "U" shape, then push it through a pencil eraser (so that it looks like a fork), you will be protected from the shock an average outlet will deliver. Fries the eraser eventually, though.
    • Ok, they clearly say in the writup that they are referring to *STATIC* electricity. The stuff coming out of your wall is not static electricity. Granted, its made of the same stuff, but wall socket electricity has a much higher amperage than static electricity does. You can shock yourself with 10000V of static electricity just by rubing some slippers across a carpet, but since the amperage is only a few hundred thousandths of an amp the total power is low, and really the total power of a shock is where all the danger is. The warning "Danger, High Voltage" is a misnomer it should really be "Danger, High Power" Electric circuits, however, are much more sensitive to even low power electric shocks, thusly 200V and a few microamps can fry a circuit, while you dont even feel it.
      • by xtal (49134)

        Yes and no. It takes about 0.183A (IIRC) to cause your heart to go into an irregular pattern, resulting in a heart attack. Higher current loads through the heart are different; They cause it to stop, and (likely) start beating again. This is the principle used to start your heart again after it's stopped beating.

        Much has to do with the resistance in ohms of your skin when you have the electrical shock applied; Are you doing something stupid like working on a grounded metal roof in wet bare feet with power tools (case study in class, that one), etc etc etc.

        Many variables are at play here; Power is dangerous and something to be resepected at any level. I zapped myself real good with 25kV once, never again .. :)

    • The strength of the current (i.e. amperes) depends on the resistance (about 500 to 1000 Ohm for the human body, AC 50 Hz): ampere = volt / ohm. The resistance depends on AC vs. DC, and also the frequency in case of AC (usually 50 Hz in Germany). In general, DC is more dangerous than AC (because the body is a better conductor for DC).

      The main danger for the body are muscle cramps, which may lead to respiratory or cardiac arrest at strengths of more than 20-50 mA after few minutes. A few 100 mA may cause cardiac arrest if lasting longer than a full heartbeat (about 0.8 sec).

      A static discharge will last only a very brief moment, so in most cases there is little reason to worry ...

  • err (Score:2, Informative)

    by crazney (194622)
    it takes 3500 volts for a human to feel a shock, but only 200 to potentially scramble a microchip.

    excuse me? it depends on the current flowing and stuff.. for example, I got shocked by 240v two days ago, and i bloody well fealt it.
    • by blixel (158224)
      excuse me? it depends on the current flowing and stuff.. for example, I got shocked by 240v two days ago, and i bloody well fealt it.

      Voltage = the rate at which energy is drawn from a source that produces a flow of electricity in a circuit

      Amperage = The strength of an electric current
      • Voltage is *NOT* "the rate at which energy is drawn from a source". What you are describing is power.

        Voltage is the electric potential between two points.

        -Jeff
  • by Brento (26177) <.moc.razotnerb. .ta. .otnerb.> on Tuesday August 28, 2001 @08:33AM (#2224864) Homepage
    "As the blurb at the end of the article says, it takes 3500 volts for a human to feel a shock, but only 200 to potentially scramble a microchip."

    You can say the same thing about water - it takes quite a few drops for humans to notice that it's raining, but just one well-placed droplet will fry your motherboard. Do you see me suing Toshiba because I can't use my laptop by the pool?
  • by ksb (517539)
    He said that damage attributable to static electricity causes losses to the global electronics industry in excess of $45 billion per year. The estimate, based on a sampling of electronics companies, includes the cost of damaged goods and their replacement, and field service for equipment repair.

    I wonder if the Damage by static is the default option in the returns database of these manufacturers ;)
  • getting shocked.... (Score:2, Informative)

    by benny_lama (516646)
    Partly wrong....you can become an electrical conductor at any voltage if the conditions are right. Besides, it takes a combination of the right voltage pushing a high enough current to hurt or kill you. 100mA conducted through the body is enough current to kill the average person. When you get zapped by static electricity, there is a potential there of about 13kV....but there is a very small amount of current....that is way you don't get hurt.
  • The complaint is:
    Palm Inc. failed to disclose that static electricity passing through its personal digital assistants could damage computers connected to the device's cradle.
    This is a half way plausable issue technically, although proving it in court to a bunch of non-technical jurors or a non-technical judge would be another issue. They further claim:
    PDA in the cradle causes a static charge to go up the cable to the desktop computer's serial port and into the machine's innards.
    I'm not entirely convinced, although if this is a problem, it would be simple for Palm to fix. All they'd have to do is ground the cradle, which could be achieved by replacing the power chord used to charge the Palm when in the cradle, with a grounded cable. It probably wouldn't cost them an outragous amount (when compared to the cost of a class-action lawsuit. I think they should fight this though. The users should know better. the Palm is clearly labeled as a computing device. Did they really think it didn't have the potential to hold a static charge...

    --CTH
    • This is a half way plausable issue technically, although proving it in court to a bunch of non-technical jurors or a non-technical judge would be another issue.

      Not as difficult as you would think since fact hardly ever enters the equation. As a private pilot, I follow the inevitable lawsuits that occur whenever someone gets hurt/killed in a plane crash. Juries routinely reward an incompetent pilot with millions from whatever deep pockets the lawyers can find despite the obvious (to anyone with an IQ of over 15) neglect on the part of the pilot. Real-life example: some idiot goes out and flies his twin engine plane into the side of a mountain. The plane itself was older than 17 years, so the manufacturer was off the hook. The magnetos in the engine had been replaced recently, though, so Bendix got sued instead, and ended up losing millions. How do the magnetos cause you to fly into a mountain? They don't, but juries don't care when they're presented with the weeping widow and teary eyed orphans. Someone has to pay, and any deep-pocketed corp. will do.
    • I'm not entirely convinced, although if this is a problem, it would be simple for Palm to fix. All they'd have to do is ground the cradle, which could be achieved by replacing the power chord used to charge the Palm when in the cradle, with a grounded cable.

      Doesn't fix the Palm III or Palm VII. Also, what if the user doesn't plug in the power cord?
    • It is grounded.
      The RS232 port's ground is also connected to system ground.
      Not to mention the outer part of the db9 connector is connected to chassis ground of the case in turn connected to power ground.

      They could just make sure that the ground of the serial port is 0V, and connect that to chassis ground.

      Need sleep, not sure if I made sense....

    • replacing the power c
      hord used to charge the Palm


      I've still got a Palm III that runs on replaceable batteries. Should I just give it the odd bit of air guitar [omvf.net] ?

  • Easily Dealt With (Score:4, Insightful)

    by skroz (7870) on Tuesday August 28, 2001 @08:38AM (#2224881) Homepage
    All they'll have to do is have a grounding connector pin placed slightly ahead of the data and power pins on the connector. Hot swap drives do this today, why can't handhelds?
  • by Ctrl-Z (28806) <tim.timcoleman@com> on Tuesday August 28, 2001 @08:40AM (#2224883) Homepage Journal

    It doesn't take 3500 volts for a human to feel a shock, naturally. It takes 3500 volts for a human to feel a static discharge, which is what the story asserted.

  • So, I wonder how this could potentially play with Docker's new pants. You know the ones that I'm talking about. They have the extra hidden pockets.
    Instead of keeping your Palm in a proper case, you carry it around in fabric where it can move around and possibly create some static and then you go to unzip and grab it and you don't even feel the zap, but then the Palm won't turn on.
    And those x-ray glasses in the ad really fool ya too.
  • The article mentions that it could destroy the serial port of your computer? So what, just replace the serial I/O card and it works again! (hmmm... these days the serial ports are on the motherboard). Unplugged your printer one too many times? Replace the printercard (euh... these days the parrallel ports are on the motherboard). Videocards? On the motherboard. USB ports? On the motherboard. IDE/FDDI cards? on the motherboard. Ethernetcards? On the motherboard. Sounddevices? On the motherboard.

    Why is everything so all integrated into one device? Why is there a chance the videocard gets broken when something happens to my serial port?

  • Uh-huh... (Score:2, Insightful)

    by weslocke (240386)
    Stephen Wise, a San Francisco accountant, said he smelled smoke and heard a crackle of static after putting his Palm Vx in the cradle. Wise claims his computer was damaged, forcing him to replace his PC during the busy tax season.

    Great example to give... certain to frighten every non-tech out there. Of course, how many times have you 'smelled smoke' from an ESD? Sheesh.
    • It can happen. The static discharge can produce a short circuit in the chip, resulting in the catastrophic destruction of the chip. I've seen chips with small craters in the middle of the package where the silicon die used to be.
  • by Simm0 (236060)
    A human can be given a shock/electricuted at even 12V given enough current.
  • Static Electricity (Score:2, Informative)

    by chrysrobyn (106763)
    I believe that the poster is unfamiliar with today's microelectronics. Yes, static electricity has gotten a bigger deal as the geometries have gotten smaller. However, do you remember the days of the PC clones with static strips nearby? If you didn't touch the static strip and were walking on carpet, you could fry the entire computer (my friend toasted two motherboards that way, by way of the keyboard). How often do you hear about this kind of thing today? (Expected answer: every now and then) How does this compare to the days that electronics were much less pervasive? (Expected answer: It happens less often)
    The reason behind this is that chip manufacturers have been working on modelling the kinds of static electricity that humans produce (human body models) and machines produce (machine models), and designing I/Os to accomodate the new parameters.
    Yes, some companies take their chances, ignoring static electricity (and there are some performance benefits to doing that), but these are risks that most of us can weigh.
  • For example, a 2-year-old whose hands wander onto the family computer could accidentally cause a static discharge -- and the equipment must be designed to withstand it, said hardware engineer Stephen Smith of Luxon, a Bay Area firm that makes graphics for portable devices.

    Of cause it should be able to withstand some amount of static, but how much is the limit before you risk a lawsuit? If we create an environment with the right combination of carpets and shoos; I believe we could kill any device. Should the manufacture then put a lawsuit against us?

    What about shock absorption? Should we put up a lawsuit, just because we dropped our palm on the floor? I think its common sense that things being dropped on the floor break... but I also thing it's obvious that high levels of static's will destroy electronics. If I produce hardware is I then responsible of educating people? What about water and electronics? Should I tell people not to plug the palm into the power sockets? Etc...

    I know it is difficult to put up the line between a bad piece of hardware and a bad use, but it appears that everything goes into lawsuits rather than trying to counteract the actual problem. Hardware may be damaged if it is badly produced and/or is misused.
  • by stienman (51024) <adavisNO@SPAMubasics.com> on Tuesday August 28, 2001 @08:54AM (#2224911) Homepage Journal
    I doubt that this is the case at all. It would be very difficult to get a charge to travel in one of the serial ports wires and not get grounded on the way there. Furthermore, the serial port, being one of the available external ports, is generally very well protected from static discharge. The real problem here is that nearly every integrated mobo has the serial port contained in the northbridge/southbridge chipset, so discharge to the port means discharge to a critical IC in the computer as well.

    Good mobos will have protection right at the port, including zener diodes and possibly MOVs (MOVs break down and conduct at high voltages, zeners prevent the voltage going above a certain point, in this case above or below 13 volts or so).

    The actual IC will generally also contain similar protection.

    But this isn't an issue of whether it happened, or is even a remote problem. This is the "The coffee burnt my lap" problem. In our increasingly litigious society we sue people for not warning us of possible problems. All computer and electronic devices say "Static electricity may cause damage to device." What these laywers apparently want is Palm to put in big bold letters that "This device may act as an additional path for static electricity to damage your computer or other palm attached device." Which is silly. The user, had they read their documentation, knows that both devices are sensitive to static. Do they think they are immune to it by ganging the devices up?

    Another lowest common denominator problem...

    -Adam
    • The real problem here is that nearly every integrated mobo has the serial port contained in the northbridge/southbridge chipset, so discharge to the port means discharge to a critical IC in the computer as well.

      I doubt that it fried anything bigger than a TTL<-->RS232 converter IC. The reason? The designs of the large ICs don't work well when designing conversion circuitry. Sure, the UART will be part of the chipset but the signals on the I/O will be TTL or CMOS level outputs.

      Those signals will then hit an IC like the MAX232 (An RS232 converter IC from Maxim Electronics) which contains the charge pumps and converts that +5/GND (or +3/GND) signal to +12/-12V required to meet the RS232 spec and back. Chipmakers like Maxim also make static-protected versions as well. (In Maxim's case, they usually designate ESD-protected devices with an E suffix.) These chips are good for a 11kV direct zap using the human body model.

      No, I don't work for Maxim. Burr-Brown (Now part of TI), National Semiconductor (now spun off to Fairchild) and a host of others make these chips. I'm just most familliar with Maxim's.

      If the motherboard fried, they used substandard (IMO) converter ICs. I've hit my laptop and several PCs very hard with ESD and I've yet to have a problem. The biggest problem is that ESD is a slow killer. Rarely does it fry something outright. Usually it just weakens the oxide layer on the semiconductor FETs and causes early death and spurious operation.

      Palm should be no more liable for this than every company which manufactures serial, parallel, USB, FireWire and really ANY external device. If the guy bought a shit motherboard, deal with it. It's not Palm's fault.

      • Palm should be no more liable for this than every company which manufactures serial, parallel, USB, FireWire and really ANY external device. Most external devices (printers, modems, mice, video cameras) are hardly ever unplugged from the computer. Palm-tops are going to be in and out of their cradle all the time. They should have put static protection in the cradle.
      • Darn, try that again...
        Palm should be no more liable for this than every company which manufactures serial, parallel, USB, FireWire and really ANY external device. Most external devices (printers, modems, mice, video cameras) are hardly ever unplugged from the computer. Palm-tops are going to be in and out of their cradle all the time. They should have put static protection in the cradle.
  • by baptiste (256004) <mike@@@baptiste...us> on Tuesday August 28, 2001 @08:57AM (#2224922) Homepage Journal
    Most people don't realize this - but computer ports are VERY exposed. Why?

    Serial ports (I'll stick with RS-232 and 485 - I'm most familiar with them) use voltage & logic shifters to handle the conversion of the port voltages to internal logic voltages. For years, most RS_232 ports on PCs used the MC148x or MAX232 type serial inetrface chips - got news for you, NONE of these chips have ESD hardening. RS-485 ports were even worse - they used a chip called a 75176 - those things would blow when you pulled one out of a pack to insert it in place of a blown chip. Ever notice how many cards with 1489type interface ICs had them in sockets? There was a reason - I've replaced a fw in mine.

    I've designed embedded boards for Home automation and our boards used RS_485 which gives you long distance (1000-4000') over twisted pair at decent speeds for system control. The original design (which I didn't do and which was done BEFORE ESD variant chips were available) used the 75176. I had customers calling for replacements all the time. Those long twisted pair cables connecting nodes together were asking to induce surges AND when folks wired them up with bare hands and no static strap - they induced charges into the wires connected to all other nodes!

    Maxim IC came to the rescue by developing the MAX232E and MAX485E which were ESD hardened interface ICs for RS-232 and 485 respectively. These things are amazing. One article I read had a guy sending massive (like 40kV) pulses into these chips and they survived. They are rated for +15kv and man do they work. When we switched to these chips (our main controller had both RS_232 and RS-485) our serial bus failures went away. TO dtae I have not had a customer complain about a failed ESD hardened chip from Maxim. Only problem is they ARE more expensive - about double. But WELL worth it IMHO.

    Obviously - anyone handling motherboards or any other bare electronic board without using a static strp is an idiot - you're just ASKING for it - and um if you unplug your PC and then ground your strap to the case - it doesn't help much sinc ethe case is only grounded when its plugged in! You have ot ground your strap to somethign thats grounded!

    But ddesigning your system with external ports and not using ESD haardened ICs and surge supressing devices is just asking for trouble - but these things cost money. Surge problems are worse than ESD often. But the savings in customer satisfaction and warranty repair costs often outweigh the extra pennies - but its hard to measure.

    As for static straps - its amazing how people hate them so. I managed a 10k sq ft data center with almost 700 servers, from small $5000 machines to monster Auspex boxes costing millions. We implemented a policy that every tech in teh room had to wear a static strap on theri wrist, shoe, or static shoes and had to test the device when they entered (testers at every door) This was for ISo compliance but it was also smart. A single board for an Auspex might cost $50,000 to $250,000!!!! Yet I constantly had to police the situation and hassle people because they refused to wear the straps. The worst were the Sysadmins - they figured since they didn't touch teh cards themselves it was OK, yet they were plugging serial cables into exposed serial ports to hook up root terminals (before we had a networked root term setup) It was amazing the resistance I encountered for such a simple thing.

    The bottom line is, if you are design a device for end use - spend the $$$ on ESD and surge suppression. If you are a tech or even a hobbiest working on teh guts of a PC or even hooking UP a PC that might not have said ESD protection, wear the strap or shoes. All it takes is one zap and thousands of dollars go up in a spark!

    • Err. you dont have to plug your device in to get a ground. thats not what the straps are for.

      if you connect your strap to a case and DONT plug it in, that is fine. the strap is there to allow you and the case to be at the same potential. As long as this is the case, you will NOT zap anything.

      Simply holding the case whilst manipulating components is enough to protect them as you insert them.

      In fact, hooking the case to mains ground is asking for MORE failures, as the harware you pick up is likely NOT to be at ground potential, so you will still zap it even then.
      • if you connect your strap to a case and DONT plug it in, that is fine. the strap is there to allow you and the case to be at the same potential. As long as this is the case, you will NOT zap anything.

        Wrong - when you pick up that motherboard sitting on teh table and zap it (cause you may not be at the same potential) you still hate it. Ground a strap to GROUND is important. Why? Because it disappates the charge from your body. Storing boards in ESD bags? They disappate any stored charge on teh board when you picj it up. Grounding your PC case - again, disappates any charge in the case.

        So yes, if you strap yourself to an ungrounded case, you won't zap the case cause you are at the same potential, but you can still zap external compnents you pick up. Yes its rare and something is betetr than nothing - I agree. But for proper protection every thing MUST be grounded. But at the bare minimum, always touch the metal of the case before messing with a PC - that helps but you STILL can zap something in a dry environment.

    • "if you unplug your PC and then ground your strap to the case - it doesn't help much sinc ethe case is only grounded when its plugged in! You have ot ground your strap to somethign thats grounded!"

      I've never quite understood this. Current only flows when you have a potential difference, right? So if you equalise yourself against the case using a strap, regardless of whether or not it is at real "ground", you still won't get any sparks generated between you and your equipment because you are both at the same potential. Or am I missing something?

      Q.

    • got news for you, NONE of these chips have ESD hardening.

      If you used which which weren't able to withstand ESD and you did nothing to protect them... you're a pretty shitty designer, or you had a shitty management (financial) decision laid down on you. It's not hard to put a 10 ohm resistor in series with the input pins, throw on a bit of a filter and finish it off with some good fast 1W transzorbs. Takes care of ESD and EMI/RFI.

      As for static straps - its amazing how people hate them so. I managed a 10k sq ft data center with almost 700 servers, from small $5000 machines to monster Auspex boxes costing millions.

      Static straps and other such protective measures are a pain in the ass. Get used to it. It probably would have been better for everyone if you just used ionizing air filters and kept the air relatively humid.

      The worst were the Sysadmins - they figured since they didn't touch teh cards themselves it was OK, yet they were plugging serial cables into exposed serial ports to hook up root terminals (before we had a networked root term setup) It was amazing the resistance I encountered for such a simple thing.

      Whenever I have to touch a computer, I make special note to touch the case often. It may not drain every last volt of potential difference from the case and I, but I've never had troubles. I'd bitch and complain if I were a sysadmin too. Or rather I would touch the case and the connector before plugging anything in.

      • you did nothing to protect them... you're a pretty shitty designer,

        err, read my post - I stated I didn't do the original design, it was inherited. and later in my post I speak the praises of using ESD and surge protection in a circuit design - but thanks for the description of my abilities all the same. I'll admit that some early designs of mine as well didn't have ALL aspects of ESD covered, but you learn as you go - or did you know it all from the start? ;)

        As for straps - they are a PIA. Agreed. But we also provided shoe straps (slip it on in the morning - take off when you leave) which wern't too bad. The HW techs got static sneakers to drain away charges since they were always swapping stuff out - the shoes used to be klunky but had become fairly stylish and felt like normal sneaks. And the bottom line is - tough shit. Your fooling around with millions of dollars of corporate hardware and you work for the company - deal with it or take a walk/find new job. I can't tell you how nervous my HW techs got holding processor cards worth hundreds of thousands of dollars - its scary! And I can tell you the heat from on high if the company faild an ISO inspection because of folks in teh computer room without ESD protection would have been immense.

        I'm still amazed that Mobo makers don't toss in dispoable straps with their retail boxed boards - hell they only cost 50 cents or so.

        • Watch those shoe straps -- they've got to stay reasonably clean to work (hard to do when you walk on them...), and when you're sitting down, your feet aren't on the ground firmly enough for them to work. We also use ground chains on the chairs, but that's effective only as a backup to wrist or ankle straps. That is, one winter day when the humidity (indoors) was low, my arm went near a metal object while getting up out of a grounded "anti-static" chair. Half-inch spark. I got out the static testing equipment, and the chair actually was grounding me as long as my weight was on it, but the trousers collected thousands of volts when separating from the chair. So keep the wrist strap hooked up until you are on your feet.

          You can put the wrist strap on your ankle instead, if that's more convenient. (Under the socks, of course, and if you're too hairy it might take a dab of conductive lotion. But the strap tester will tell you that, anyway...)

          All of this is beside the point in regards Palm's responsibility. We assemble circuit boards, we handle semiconductors, we've got to learn this stuff and buy the necessary equipment. So do electronic techs and anyone else who is going to get inside the electronics box. Palm's customers are mainly businessmen, not techies -- they never open the box and aren't going to learn ESD control. Palm should have designed to handle it -- it just takes a few cents worth of diodes and ferrite beads.
  • Instead of soldering the chip to the motherboard, just fasten it with a piece of play-doh. Or better yet, an eraser - they're made of rubber so the static electricity can't pass through them - problem solved!

  • Can I sue the makers of poly-propylene for toasting my palm? I get zapped non-stop while wearing this stuff.
  • IIRC from my early Computer Engineering classes, all it takes to damage a circuit is +5 volts or static electricity. It seems like it was something around +10,000 volts of static electricity before we as humans feel it. I think that's right. I'll have to dig out my old books. They showed a demonstration video of a typical engineer in a simple short sleeved button down shirt (plain) and simple tie. He neutralized himself (voltage equalization IIRC). Then someone (also equalized) held the tie at shoulder level just away from the 1st guy's shirt. He let go and let the tie brush against the guy's shirt. They then measured how much static electtricity was generated. It was more than enough to damage a circuit board. Mind you, +5v probably won't toast a board right away but it could easily cause damage that shows up down the road. IIRC correctly of course. It's been a while since I had that class.
  • by Vuarnet (207505) <luis_milan.hotmail@com> on Tuesday August 28, 2001 @09:02AM (#2224935) Homepage
    From the article: "You cannot expect people to become more educated," Smith said. "The equipment has to be perfectly safe."

    See, here's why there are so many lawsuits and bad stuff (like the DMCA... do I get extra karma points for mentioning the DMCA in a completely unrelated discussion? Ah well, nevermind) happens.

    Expectations. If you don't expect people to be educated, then they never will be. Instead of having so many lawyers going "my poor client didn't knew thay you shouldn't stand at the top of a 15-foot metal ladder in the middle of a thunderstorm, while installing his TV antenna", you should get more judges who think "Serves you right for being such an idiot. Next case!".

    I agree that sometimes consumers must be protected from Evil Corporations Who Want To Take Over The World, but there's a big difference between: a) not letting oneself get screwed by the Evil Corporations etc.; and b) blaming the Evil Corporations etc. for each and every stupid accident that could have been prevented with a little common sense.

    As usual, let's blame the lawyers instead.
    • There used to be something called the "reasonable man" standard. (Yes, it's a sexist term. This was a while ago.) Basically, the courts asked whether an average, ordinary reasonable mind would have seen the danger. If so, no liability applies for the manufacturer, since the user "should have known better". Alas, setting the bar for a "reasonable" mind is hard and the standard appears to have fallen away.
      • The "reasonable person" was taught in my paralegal classes as last as last semester--and it doesn't seem to be getting loose.

        In addiontal to "common sense", a reasonable man never comits a tort, nor does he ever fail to read everything he agrees to, nor the instruciton manual of anything he gets.

        A simple "warning, these are very succeptible to static electricty" would probably suffice for the PDAs, but then again, IANAL.
      • Think "programmer with screwdriver" or "phd with soldering iron". Common sense and intelligence often seem to be inversely proportional.
        • Blockquoth the poster:

          Common sense and intelligence often seem to be inversely proportional.

          Indeed. Which is why the standard was a "reasonable man" and not, say, a "well-educated man". The idea is, there are certain rules of living that one evolves as one moves through the world, and -- quite a hypothesis here! -- such rules are, within a certain fuzzy box, common to everyone and recognizable by anyone reasonable.



          "Reasonable man" and "common sense" are not exactly the same thing but are very related.

    • This equipment has to be perfectly safe

      ... said the lawyer as he got in his Ford Explorer to drive home.

  • From the Just-Because-You-Disagree-Doesn't-Make-It-Wrong department, this just in:


    It's not about AC vs. DC at all. The article is referring to static discharge, which is the equilization of differing voltage levels. Here [google.com]'s the google cache of the first decent explanation I dug up on google. I'm sure you can find more yourself.

  • Have you shocked yourself on a speaker? A Mouse? A Keyboard? Each of those devices can roast the computer it's attached too. I don't remember seeing people run around sueing the manufacturers of those devices. The same 'ground yerself before you touch' principle holds up for any device attached to a computer.
  • by bellers (254327) on Tuesday August 28, 2001 @09:44AM (#2225088) Homepage
    I have a Handspring Visor (well, I've had 2 of them). At work, I noticed that my system had the decidedly unhealthy habit of occasionally performing a hard reset the moment I set the Visor in the cradle. Driver upgrades and firmware revisions to the desktop did not alleviate the problem.


    3 months into my new Visor, I had one final hard reset incident, and after that my USB port became non-functional (I also have a USB Zip drive that I use several times a day, so I can tell you precisely when it died). Hardware support happily arrived and replaced the system board in my Dell, but I was wondering what could possibly by the problem that caused the failure in the first place?


    Eventually, I exchanged the Visor, and brought the new one back to work. I put it in the sync cradle. *reboot*.

    At this point, I knew it wasnt the Visor, and I knew it wasnt the Dell, but it was obviously some combination of the two. As an experiment, I went a week with a grounded anti-static wriststrap wrapped around the back of the sync cradle. I made a point of touching it before I set the Visor in the cradle. Lo and behold, no more hard resets!

    I decided to make this modification more or less permanent. I found the ground cable in the cradle, and the corresponding copper spring clip where it mates to the Visor. Using a trusty set of hemostats, I bent and extended it up to where it is the first bit of the cradle that touches the Visor. On the other end of the sync cable, I ran a little pigtail wire from the metal sheath of the male USB port to a screw on the back of the case.


    This has the benefit of directing any static directly to the ground of the case, instead of routing the discharge through the USB controller, to *it's* ground.


    Now, I dont really know whether or not this worked, because static shocks are pretty rare here in the summer (St. Louis, MO, where the humidity rarely drops beloe 75%). I'll have to wait until this winter, when the central heat kicks in, and the relative humidity in the office is about 15% before we see whether or not I've improved my sync cradle.

  • "it takes 3500 volts for a human to feel a shock, but only 200 to potentially scramble a microchip"

    When will the world catch on that it is not the volts that matter, but the amps! I can hit you with a million volts at .000005 amps and you will never notice, but one hundred volts at five amps will light your ass up!
  • The article only mentions cradles attached to a serial port. Does this affect cradles attached to a USB port as well?
  • Just a small scratch on the touchscreen plastic can ruin a Palm totally. And the repairs to replace the entire screen cost something like...$100?

    It's rather silly that the plastic plates are not available separately. But I guess they have calculated that they make more money selling entire new screens or even new PDAs...

    I'd call that level of repairability as useless. People really should pay more attention to this kind of problems.

  • by manon (112081)
    Things are more complex than just the amount of voltage you get through your body. One can die from 400V and survive from a shock of 10000V. How come? The current is very important and so is how well you are grounded.

    (The funny thing is, the 220V (110V US) we use daily is less dangerous than the 24V in your phone when ringing.)

    How much current is dangerous? Well, 5 milliamperes can be felt, 10 will be felt and hurts, 15 will really hurt, 30 will freeze you on to the current source. And we are just talking about milliamperes people.
  • This is probably a place that has never heard of a humidifier... I once did a service call at a local univeristy office, they had steam heat, and I was getting ZAPPED with inch long arcs (~30KV). I wasn't surprised at all when attempts to connect printers to a switchbox resulted in problems, anytime the switch was moved, something went wrong. I left the case before it was resolved.

    If you're running ANY electronics in an environment like that, you'll see it die, eventually, if not sooner. It doesn't matter what you connect, once you put a wire outside of the computer, it's another route for things to get zapped.

    --Mike--

  • A few tips from an old ESD compliance tester:
    • Fabric softener is your friend. A dilute solution on all fabrics in the area (esp. carpet) can save a fortune.
    • Ferrite Is Good. A clamp-on ferrite (much easier to find in Japan than in the USA, dang if I know why) around a cable does wonders to slow down current edges so that the ESD devices have a chance to swallow the charge. No, it won't hurt your signal speed (differential vs. common-mode propagation.)
    • Common Ground. It's amazing how often you have two devices hooked together by (e.g.) a USB cable but plugged into different outlets. This makes the grounding at one useless-to-dangerous to the other.

  • Testing for ESD (Score:2, Informative)

    by scharkalvin (72228)
    Thirty years ago I worked for Digital Equipment Corp, as a systems testing engineer. Our department did hardware and software testing of all systems configurations that went out the door, I worked on the LSI-11 based stuff. One of the tests we had to do was for ESD, or static discharge as it was there called. The test consited of drawing an arc from any exposed surface of the equipment, to pass it had to withstand an arc of at least 5000 volts (IIRC). The tester was a high voltage power supply that could be adjusted to as high as 15kv (it was limited to a few MA). The probe was an old VTVM high voltage probe with the tip replaced by a metal sphere about 6-8" in diameter. The tester would crank up the voltage and pass the sphere around the outside of the computer to draw an arc from various locations as the computer was running a systems diagnostic. There had to be no systems failures. Usually we didn't fry anything (I can't remember ever destroying anything), but sometimes the diagnostic would fault or the computer would re-boot when the arc was drawn. I wonder if any of todays PC's could pass such a test? (Not running windows!, probably get the BSOD when you draw an arc!).
  • by wirefarm (18470)
    ...damage attributable to static electricity causes losses to the global electronics industry in excess of $45 billion per year...

    Would that include lightning strikes? (If I remember gradeschool science correctly, lightning is static electricity on a big scale...)

    $45 billion dollars? that sounds kind of high - Any chance Bill Gates will off himself scuffing across the carpet in his slippers next year?

    Cheers,
    Jim in Tokyo
  • I do electrostatic discharge and interference tests for a living. We can produce electrostatic discharges ranging from a few hundred volts to over 300 thousand volts (landing aircraft) in house. We also radiate products with radio frequency interference from a few hundred kilohertz up to the microwave range. Sometimes we just listen to what products put out as well.

    Most of the devices we test are safety-critical. Your home computer likely will never be seen in our lab. We recently conducted a test where a product in its box was shocked with a 300 kV static discharge. The spark (besides traveling three feet) went through the box, in one terminal of the item, and out another.

    While charges on your body are not nearly that strong (the highest you'll build up likely is 25-30 kV), you shouldn't laugh at them.

    Many modern manufactuers no longer include safety components ment for repair technicians. Often saving less than a fraction of a cent (in bulk), the lack of these parts make it an extreme risk to open things like microwaves and televisions. Not to be dismal, but don't open these items unless you know what you are doing; I have heard of experienced technicians putting their hand in the wrong place and regretting it.

  • Quick and simple [apc.com].

    On another topic: Your comment violated the postercomment compression filter. Comment aborted

    Lose the lameness filter, Taco.
  • Yes, believe it or not, modern computers are quite sturdy. I've beveled the edges of my Duron with homebrew watercooling tech., I've passed current through my heatsink (melting the contact points to boot), hooked up who knows what to the serial ports, and currently my tv card is being fed via telephone wire because I ran out of coax. On top of that, I unplugged and then plugged back in my cdrom drive while my computer was running, producing a bright arc of electricity and a seemingly dead motherboard, which I revived the next day. These people are either unlucky that their computer fried, bought cheap crap, or they want cash (probably the latter).

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