A Hidden Threat To Handhelds 214
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.
Easily Dealt With (Score:4, Insightful)
Uh-huh... (Score:2, Insightful)
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.
Having to deal with this... (Score:3, Insightful)
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
ESD isn't a joke - but everyone thinks it is (Score:4, Insightful)
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!
This quote says it all... (Score:4, Insightful)
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.
I can speak firsthand about PDA/Desktop damage. (Score:4, Insightful)
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.