14 Mar
2005
14 Mar
'05
9:12 a.m.
From: "Tom Jennings" <tomj at wps.com>
CMOS isn't *THAT* sensitive; easy, benign, reasonable precautions
are more than adequate. Ben, the days of early MOS/CMOS
hypersensitivity to static are long gone. Even 1970's 4000 series
had input-protection diodes.
The 4051,4052 and 4053 were very static sensitive. But it
is try that most were relatively insensitive. Still, if you
are hitting a part with a spark large enough to make
a sound, you are most likely doing some damage, even if
it doesn't show right away.
Dwight
15 Mar
15 Mar
noon
New subject: Static damage was Re: OT Troubleshooting: Old computers with modern parts
From: "Dwight K. Elvey" <dwight.elvey at amd.com>
From: "Tom
Jennings" <tomj at wps.com>
CMOS isn't *THAT* sensitive; easy, benign, reasonable precautions
are more than adequate. Ben, the days of early MOS/CMOS
hypersensitivity to static are long gone. Even 1970's 4000 series
had input-protection diodes.
The 4051,4052 and 4053 were very static sensitive. But it
is try that most were relatively insensitive. Still, if you
are hitting a part with a spark large enough to make
a sound, you are most likely doing some damage, even if
it doesn't show right away.
Dwight
From dvcorbin>
Duiring the '70s and '80s I worked at a company that made
many military and space grade components. A percentage
were de-lidded at the end of each lot and sent to a SEM
(Scanning Electron Microscope) to look for static damage,
that had NOT effected functionallity. If any (above a very
small threshold) was found, the ENTIRE lot was scrapped
[although they really became samples, lab grade, etc...]
It was AMAZING, the various craters and cracks that were
caused by static that you could not see, feel, or hear....
Wish I still had some of the prints....
The damage without imediate failure of components by static is known as
"Latent Failure", and is a very real problem. These failures can show up as
apparently random device failures for many years after the damage was done.
As an example, one of the systems I look after is a remote control system
for radio transmitters and receivers, and it uses CMOS ic's in FSK modems to
send and receive control signals to the remote equipment. It was installed
in around 1982, and soon gained a terrible reputation for reliability - if
you went a day without a fault, you were doing well! When I joined the
section in 1991, as the new boy, I was given this to look after :-( I, along
with another new, young engineer implemented anti static precautions around
the kit (they hadn't seen much CMOS before this, and where of the opinion
that if it didn't fail imediatly, why was everyone making such a fuss...).
After a couple of months, the failure rate dropped dramatically. The kit is
still working (approaching its 25th year), and now it is rare to touch it
from one anual maintenance to the next!
Interestingly, the previous generation of radio remote control equipment
(built around 1967, and still going strong!), used a qauntity of 74 series
TTL, and despite no ESD precautions, has hardly had any of it's logic
devices changed (wish I could say the same about the germanium transistors
in the alarm shift register - a 24 bit serial in parallel out unit built
with discrete components, and runing at around 4bits / second - you need a
storage scope to fault find).
I take ESD very seriously on all logic systems, especially classic ones - I
would hate to accidentally "zap" that irreplaceable chip...
Jim.
12:08 p.m.
New subject: Static damage was Re: OT Troubleshooting: Old computers with modern parts
Jim Beacon wrote:
From: "Dwight K. Elvey" <dwight.elvey at
amd.com>
>>From: "Tom Jennings" <tomj at wps.com>
>>
>>CMOS isn't *THAT* sensitive; easy, benign, reasonable precautions
>>are more than adequate. Ben, the days of early MOS/CMOS
>>hypersensitivity to static are long gone. Even 1970's 4000 series
>>had input-protection diodes.
>
> The 4051,4052 and 4053 were very static sensitive. But it
>is try that most were relatively insensitive. Still, if you
>are hitting a part with a spark large enough to make
>a sound, you are most likely doing some damage, even if
>it doesn't show right away.
>Dwight
>
I've changed an unholy amount of these in old analogue synthesizers.
Ensoniq Mirages seem to be the worst for it.
Gordon.
12:31 p.m.
New subject: VCF East 3.0 ?
No time like now to start preparing...
So what is the status of VCF East this year? Approx date/month? Are
we gonna have it at Sun again? It was nice having it there, but the
logistics of security, sign-in and getting equipment in were rather rough.
Curt
8:49 a.m.
New subject: VCF East 3.0 ?
On Tue, 15 Mar 2005, Curt @ Atari Museum wrote:
No time like now to start preparing...
So what is the status of VCF East this year? Approx date/month? Are
we gonna have it at Sun again? It was nice having it there, but the
logistics of security, sign-in and getting equipment in were rather rough.
Not sure. I made initial forrays into finding a location but nothing
concrete so far. Sun is a no-go. Had an interest from the folks at the
Boston Museum of Science but they flaked.
Haven't given it much thought since. For the time being I'm focusing now
on a VCF Midwest and trying to finish some time critical projects that are
taking up all my time.
When I do start thinking about it again, it will be whether or not I'm
going to actually hold it this year since I have some other plans that
take priority. Sorry to have to say that, but I just don't want to let
anyone down.
There's still the possibility to organize it from afar if I can get a
local host, but there would only be a 50/50 chance I would actually attend
myself.
--
Sellam Ismail Vintage Computer Festival
------------------------------------------------------------------------------
International Man of Intrigue and Danger http://www.vintage.org
[ Old computing resources for business || Buy/Sell/Trade Vintage Computers ]
[ and academia at www.VintageTech.com || at http://marketplace.vintage.org ]
16 Mar
16 Mar
7:29 a.m.
New subject: VCF East 3.0 ?
When/where will the VCF Midwest be?
-Bob
On Tue, 15 Mar 2005, Curt @ Atari Museum wrote:
--
bbrown at harpercollege.edu #### #### Bob Brown - KB9LFR
Harper Community College ## ## ## Systems Administrator
Palatine IL USA #### #### Saved by grace
No time like now to start preparing...
So what is the status of VCF East this year? Approx date/month? Are
we gonna have it at Sun again? It was nice having it there, but the
logistics of security, sign-in and getting equipment in were rather rough.
Not sure. I made initial forrays into finding a location but nothing
concrete so far. Sun is a no-go. Had an interest from the folks at the
Boston Museum of Science but they flaked.
Haven't given it much thought since. For the time being I'm focusing now
on a VCF Midwest and trying to finish some time critical projects that are
taking up all my time.
When I do start thinking about it again, it will be whether or not I'm
going to actually hold it this year since I have some other plans that
take priority. Sorry to have to say that, but I just don't want to let
anyone down.
There's still the possibility to organize it from afar if I can get a
local host, but there would only be a 50/50 chance I would actually attend
myself.
--
Sellam Ismail Vintage Computer Festival
------------------------------------------------------------------------------
International Man of Intrigue and Danger http://www.vintage.org
[ Old computing resources for business || Buy/Sell/Trade Vintage Computers ]
[ and academia at www.VintageTech.com || at http://marketplace.vintage.org ] 
10:48 a.m.
New subject: VCF East 3.0 ?
Bob Brown wrote:
When/where will the VCF Midwest be?
Oo! Please say Illinois!
--
Jim Leonard (trixter at oldskool.org) http://www.oldskool.org/
Want to help an ambitious games project? http://www.mobygames.com/
Or check out some trippy MindCandy at http://www.mindcandydvd.com/
15 Mar
15 Mar
6:33 p.m.
New subject: Static damage was Re: OT Troubleshooting
The reliance on ESD protection diodes is way over-sold. From EDN Dec,2004;
"On a schematic, ESD-protection diodes resemble the diodes engineers
sometimes use to limit overshoot and undershoot on a high-speed bus, but
with one significant difference: the expected lifetime of the diode. An
overshoot-limiting diode is huge compared with its ESD-protection cousin,
and, because of its large size, the overshoot-limiting diode can absorb
pulse after pulse of high-powered current transients, lasting essentially
forever. ESD-protection diodes, on the other hand, are small, have limited
strength, and aim to handle only a few events in their lifetime. "
At Hughes we conducted (no pun intended) failure analysis on any electronic
parts we thought may have been compromised (not just CMOS). The parts were
de-capitated and scanned (as stated in the other thread). Equipment shot
into space cannot tolerate latent defects, as in those days we didn't have a
shuttle that could bring back the close orbit satellites. With the high
density sub-mil geometry's in IC's now ESD is a huge problem. A lot of dies
have "spark gaps" incorporated into the etch. Below is some typical and high
end readings for ESD voltages (source: Fairchild ESD Application Note:
AN-248).
Person on carpet: 12,000 V (highest reading 39,000 V)
Person on Vinyl : 4,000 V (highest reading 13,000 V)
Person on workbench: 500 V (highest reading 3,000 V)
16 Pin DIPs in plastic box 3,500 V (highest reading 12,000 V)
I think you get the idea. The diodes are normally tested at 400 Volts. After
multiple ESD hits the diodes fail open and go to their maker.
Best regards, Steven C.
Jim Beacon wrote:
From: "Dwight K. Elvey"
<dwight.elvey at amd.com>
>>From: "Tom Jennings" <tomj at wps.com>
>>
>>CMOS isn't *THAT* sensitive; easy, benign, reasonable precautions
>>are more than adequate. Ben, the days of early MOS/CMOS
>>hypersensitivity to static are long gone. Even 1970's 4000 series
>>had input-protection diodes.
>
> The 4051,4052 and 4053 were very static sensitive. But it
>is try that most were relatively insensitive. Still, if you
>are hitting a part with a spark large enough to make
>a sound, you are most likely doing some damage, even if
>it doesn't show right away.
>Dwight
>
I've changed an unholy amount of these in old analogue synthesizers.
Ensoniq Mirages seem to be the worst for it.
Gordon.
7224
days inactive
7226
days old
7 comments
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participants (8)
-
bbrown＠harpercollege.edu -
cannings＠earthlink.net -
curt＠atarimuseum.com -
dwight.elvey＠amd.com -
gordon＠gjcp.net -
jim＠g1jbg.co.uk -
trixter＠oldskool.org -
vcf＠siconic.com