wilkins@jarthur.Claremont.EDU (Mark Wilkins) (11/18/89)
In article <4129@phri.UUCP> roy@phri.UUCP (Roy Smith) writes: >In <cZMlnuG00WB404Z0cv@andrew.cmu.edu> kn0j+@andrew.cmu.edu (Kenneth Blake >Nerhood) writes: > >> do I have to have a dealer install it or can I do it easily? > > I'll only address the technical issues -- there are also problems >of warranty violations and the like of which I know little. Plugging in a >SIMM is pretty trivial -- if you can plug in a PC board, you should be able >to plug in a SIMM. You put the edge with the contacts into the socket and >then gently push it over to one side until the plastic clips engage the >holes in the SIMM PC board. If you decide to install your own SIMMs, PLEASE, PLEASE use proper static protection. The circuitry is extremely sensitive to static discharges which you may never notice until you boot your machine and get a sad mac, and this applies to the Mac internals as well as the RAM. The solution to this problem is either to wear a static bracelet, usually an elastic bracelet with a metal piece at the wrist, which has a wire which you connect to the case of the machine so that your wrist is grounded, or to touch the power supply's metal case with your working hand and hold onto it with the other hand while you work. Sound like a hassle? It is. It's the main reason that doing this will void your warranty. And this sort of care is what you pay for when you get a dealer to do it. If you routinely do this sort of work or you know someone who does, then go for it. I just installed 4 megs of RAM yesterday. If you feel even a little uncomfortable, then consider that it might be better to pay someone $50 and be safe rather than lose $500 worth of memory or $5000 worth of computer. -- Mark Wilkins wilkins@jarthur.claremont.edu P.S. Followups to comp.sys.mac.hardware
roy@phri.UUCP (Roy Smith) (11/19/89)
In <3122@jarthur.Claremont.EDU> wilkins@jarthur.UUCP (Mark Wilkins) writes,
in response to my instructions for installing SIMMS:
> PLEASE, PLEASE use proper static protection.
Yes, absolutely. I meant to mention that in my article but forgot,
so now all I can do is endorse what Mark says. My rule of thumb about
static protection is "be paranoid". I use a 3M model 8501 anti-static kit
which has conductive pad to lay the machine or board on, a grounding clip
which you can attach to the chassis frame ground, and a conductive wrist
strap. Cost me $55 and worth every penny. You may not be able to justify
something that sophisticated, but use something!
--
Roy Smith, Public Health Research Institute
455 First Avenue, New York, NY 10016
{att,philabs,cmcl2,rutgers,hombre}!phri!roy -or- roy@alanine.phri.nyu.edu
"The connector is the network"jg13@umd5.umd.edu (Allon Stern) (11/24/89)
In article <3122@jarthur.Claremont.EDU> wilkins@jarthur.UUCP (Mark Wilkins) writes: >touch the power supply's metal case with your working hand and hold onto it >with the other hand while you work. (this to prevent zapping the motherboard/simms with static) My question is, does the computer have to be plugged in to do this? It seems that in order to get a ground it would have to be.
wilkins@jarthur.Claremont.EDU (Mark Wilkins) (11/25/89)
I wrote: >>touch the power supply's metal case with your working hand and hold onto it >>with the other hand while you work. In article <5671@umd5.umd.edu> jg13@umd5.umd.edu (Allon Stern) writes: >My question is, does the computer have to be plugged in to do this? It seems >that in order to get a ground it would have to be. Sorry, forgot to mention that. With all static sensitive circuitry it is necessary to leave the machine off but plugged into a grounded outlet. -- Mark Wilkins wilkins@jarthur.claremont.edu
pepke@loligo (Eric Pepke) (11/27/89)
In article <3231@jarthur.Claremont.EDU> wilkins@jarthur.UUCP (Mark Wilkins) writes: >I wrote: > >>>touch the power supply's metal case with your working hand and hold onto it >>>with the other hand while you work. > >In article <5671@umd5.umd.edu> jg13@umd5.umd.edu (Allon Stern) writes: > >>My question is, does the computer have to be plugged in to do this? It seems >>that in order to get a ground it would have to be. > > Sorry, forgot to mention that. With all static sensitive circuitry it is >necessary to leave the machine off but plugged into a grounded outlet. This is dangerous, especially if you are grounded through a different path. If the machine is plugged in to the wall, there is always the chance that you will touch the hot, in which case you may die. The best way is to ground yourself and the machine to a common ground that has nothing to do with power. You can use the grounding hole of an outlet, but only if you are absolutely sure that it is a true ground. There are a lot of outlets out there with floating grounds or grounds that are just tied to the neutral. If you do use a wall ground, be sure to use one of those plugs where the flat prongs are non-conductive plastic and only the ground prong conducts. Also be sure to use a ground strap that contains a resistor for safety; in theory, it is supposed to lower the current to below what usually causes fibrillation in a healthy person. In practice, those that live the longest tend to be those who avoid tempting fate and safety mechanisms. Better than a grounding outlet is a real ground, such as a cold water pipe. When you are connected to a ground, never go anywhere near anything that could be live. When you want to plug in the Macintosh to test it, first disconnect yourself completely from the ground. Eric Pepke INTERNET: pepke@gw.scri.fsu.edu Supercomputer Computations Research Institute MFENET: pepke@fsu Florida State University SPAN: scri::pepke Tallahassee, FL 32306-4052 BITNET: pepke@fsu Disclaimer: My employers seldom even LISTEN to my opinions. Meta-disclaimer: Any society that needs disclaimers has too many lawyers.
rieman@boulder.Colorado.EDU (John Rieman) (11/29/89)
[a series of articles suggest grounding yourself to various household objects...] Like outlets, cold-water pipes are only theoretically safe. Water utility folk and plumbers are taught to exercise extreme care with water pipes, since a faulty appliance can turn the cold-water pipe "hot." Even if the pipe is a good ground, wiring yourself to it while you open up a 110V device is less than smart -- it's too easy to get caught up in the excitement and plug the Mac back in, just to see if it's gonna run. Then when the bomb appears, you figure you'll just wiggle a board and... PZZZZT! Anyway, as I understand it, what you want is not (necessarily) an absolute "ground." You just want the potential between you and the machine to be zero. If you're both floating at 500 V relative to some Platonic ideal ground, no problem. The recommendation I've read, which I've seen VAX, Apple, and various other professional computer service people follow, is just this: Unplug the machine, snap a grounding strap around your wrist, and clip the lead from the grounding strap to the machine's chassis. For board-level work, such as installing chips, try to find a metal desk or table, and ground yourself and the equipment to that. (Don't wear polyester and don't shuffle your feet -- probably good advice in any case.) - john