15 Aug
1998
15 Aug
'98
6:56 p.m.
Unfortunatly the subject line describes how a bunch of the PDP-11/03 boards
that I got today came. What is the chance that they are operational?
Zane
| Zane H. Healy | UNIX Systems Adminstrator |
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+----------------------------------+----------------------------+
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15 Aug
15 Aug
6:14 p.m.
On Sat, 15 Aug 1998, Zane H. Healy wrote:
Unfortunatly the subject line describes how a bunch of
the PDP-11/03 boards
that I got today came. What is the chance that they are operational?
I got a bunch that way recently, too. But mine came from a distinguished
scientist who should've understood that aluminum is a conductor :-( Just
don't rub your feet on the carpet for good luck before you unwrap them.
-- Doug
6:27 p.m.
As I understand it, the idea is to keep the whole board at the same
potential, whatever that is. Damage only happens when you get one
part of the board grounded and another part hits a higher (or lower)
potential; current flows through components, probably in ways not
intended, and certainly at higher voltages than normal if it's static
electricity. I would think you could wrap a board in foil, charge it
up to a few thousand volts of static electricity, and then ground the
foil with a big blue spark and no damage to the board. If the
wrapping being conductive is a problem, why does the whole industry go
to such pains to use conductive foam, peanuts, and metallic plastic
bags?
-Bill Richman
bill_r(a)inetnebr.com
http://incolor.inetnebr.com/bill_r
(Home of the COSMAC Elf microcomputer simulator!)
6:19 p.m.
New subject: Apple TechStep CPU Tests
Hey, Apple weenies, I just picked up a dignostic ROM for the Mac LC, LCII,
and CLSII. It includes trouble-shooting docs. $12000 or best offer :-)
-- Doug
6:34 p.m.
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7:12 p.m.
On Sun, 16 Aug 1998, Tony Duell wrote:
The foil forms a faraday cage round the boards and
protects them from
static. About the only danger from wrapping boards like this is that if
the foil and board are at different potentials when wrapped, there will
be a diacharge from the foil to the board. But apart from that, it's
perfectly OK to wrap them in foil.
Time for me to brush up on my physics. So, does this really work well in
practice? It seems to me that when I'm holding a board in one hand, I'm
grounding any components that happen to be touching the foil, but there
will be plenty of microgaps. If I then zap the foil, I would guess my
chance of zapping more than one component would be greater than if the
board were either completely isolated from the foil or completely in
contact.
-- Doug
7:16 p.m.
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7:34 p.m.
On Sun, 16 Aug 1998, Tony Duell wrote:
Remember that you essentially have a hollow conductor
with no charges
inside. The electric field inside such a conductor is 0. So no zaps at all.
Got it. So the main danger would be when the pins start poking holes in
the foil, have a little clearance around them, and then I zap the pins
directly.
-- Doug
7:34 p.m.
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16 Aug
16 Aug
8:22 a.m.
On Sun, 16 Aug 1998, Tony Duell wrote:
Yep... Although actually, that's not that big a
problem. Use a couple of
layers of foil and you should be OK...
Got boards you need to store safely? Drop in any PC store that builds
systems in house. They have should bunches of anti-static bags & boxes
headed for the trash. I got a bunch yesterday from regular PC
motherboards that were a perfect fit for some UniBus stuff.
-wayne
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