-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 The Monday 2006-10-23 at 20:52 -0500, Rajko M wrote:
The magic that burns electrostatic sensitive parts is amount of electrostatic charge that will go trough the part driven by potential (voltage) difference between human body and the part. Not every static is damaging, but in the winter our skin is dry enough to load quite a bit.
I know. But in my case the operator is probably at ground potential: humidity of 80%, artificial stone floor.
Attached ground to the chassis will not help if operator forget to use antistatic strap attached to the metal part of the case, but then the for the safety reasons cord must be unplugged from the wall outlet, because you are accessing malfunctioning device where you have no idea what is wrong. That means you have to find a ground that is for sure ground, and not "it should be ground", because "it could be line voltage" as well.
For that reason, good antistatic straps have a 1..5 meg resistor in series ;-)
Second reason not to use this method is construction of todays computers, where "switch" is just a signal key that tells motherboard to turn power supply on. So there is no real separation of electric power (110 VAC) like it was some 10 years ago. Thanks to Stan to remind us on this.
True. But good poower supplies also have a "real" switch at the rear. That's the one I meant. You can also switch it off at the main connection bar.
Groundign everything and using antistatic straps is valid in industry where worker/operator has to touch many objects and in the same time has to focus on job, not on ESD (ElectroStatic Discharge) problems.
It's easy to forget to "touch metal" periodically and often.
On a single device it will work without straps, but with unplugged power cord, as long as repairer has in mind that discharging is not one time process, but it has to be done after each contact with something outside the computer case.
Just walking a few meters on a carpeted room does it.
Did I mentioned, that disconnected cord helps a lot against bad luck. I'm not that superstitious, but by now it helped better than a rabbit foot.
X-) - -- Cheers, Carlos E. R. -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.2 (GNU/Linux) Comment: Made with pgp4pine 1.76 iD8DBQFFPe0WtTMYHG2NR9URAt1UAJ9LJrKW6Bt9GCFaWZcdhGv1yDg54ACfVd2j A+kVCpScQ8kfztELn2c3hjs= =wr/j -----END PGP SIGNATURE-----