[sci.electronics] Static and crashing PC's

levene@APLPY.JHUAPL.EDU (Robert A. Levene) (02/05/91)

Here's the story:

I have a formica computer table with metal legs.  I also have a standard
office chair with metal legs atop plastic casters.

Just by sitting in my chair I generate enough static electricity to cause a
spark when I touch ground.  The chair also gets charged up, and when the
chair leg gets close to the table leg, a spark is generated.

My '83 TI Professional Computer (an MS-DOS machine) immediately crashes, as
indicated by the immediate blanking of the screen.  A Vulcan-neck-pinch
(ctrl-alt-del) is necessary to re-start the machine.  Both the TI Pro
and the Macintosh on the table are connected to an ISOBAR surge protector.
(The Macintosh SE is unaffected.)

My troubleshooting included:

 (1) checked the office ground

     - It is intact.

 (2) disconnected all extraneous connections, leaving only the Keyboard
     and the video plugged in

     - The system wouldn't crash without the keyboard plugged in

 (3) swapped keyboards

     - The systems crashed on the second or third spark


Anyone out there have any ideas apart from "Reduce your static?"  Perhaps
the spark generates enough EMP to crash the TI-Pro video board?

Please e-mail and I'll summarize the results if there's enough interest.

- R

-- 
Robert A. Levene     Internet: levene@aplcomm.jhuapl.edu   Bitnet: RXL1@APLVM

Disclaimer: I speak neither for my race, my culture, my country, my religion,
            my political party, nor my employer, but for me alone.

dunne@motcid.UUCP (Jim E. Dunne) (02/06/91)

From article <9102041615.AA04354@aplpy.jhuapl.edu>, by levene@APLPY.JHUAPL.EDU (Robert A. Levene):
 
> My '83 TI Professional Computer (an MS-DOS machine) immediately crashes, as
> indicated by the immediate blanking of the screen.  A Vulcan-neck-pinch

  There's the problem!  You're using a TIPC (pronounced Tipsy).  Miserable
  wretch of a machine, even a DOS machine at that.  About 70%
  compatible with true DOS machines (major differences were diskette
  formats and graphics).  When I worked for TI I was provided with a
  screaming 4.77 Mhz job, with mono graphics and 2 floppies!  Used to
  crash when you looked cross-eyed at it, often requiring a power cycle.
  I don't recall any static-related problems, though.  TI machines got 
  even worse (TI BuisinessPro) until they went totally DOS-compatible.

levene@aplcen.apl.jhu.edu (02/06/91)

I wrote:

>> [Due to a nearby spark between my chair and the legs of the table on
>>  which the TI Pro is placed,] 
>> My '83 TI Professional Computer (an MS-DOS machine) immediately crashes, as
>> indicated by the immediate blanking of the screen.  A Vulcan-neck-pinch

In article <4547@ash17.UUCP> dunne@motcid.UUCP (Jim E. Dunne) responds:

>  There's the problem!  You're using a TIPC (pronounced Tipsy).  Miserable
>  wretch of a machine, even a DOS machine at that.
[deleted]

Yeah, and while you're at it, how 'bout making fun of the
1973 Dodge Dart V-8 which I used to drive a few years ago. ;-)

There have been about 4 or 5 replies, and the general consensus is
that lots of strange things could be causing the crash to occur, so
it's better to take steps to reduce static electricity, as in:

  Patient: "Doc, it hurts when I move like this." 
  Doc:     "Well, then don't move like that!"

The most common solution recommended was to connect a small touch
plate to ground and place the plate near the keyboard to enable quick
discharging before touching magnetic media.  I also made a similar
set-up for my chair, so that it discharges to ground before it can
touch the table leg.

Thanks for your responses,

Rob

-- 
Robert A. Levene     Internet: levene@aplcomm.jhuapl.edu   Bitnet: RXL1@APLVM
               
Disclaimer: I speak neither for my race, my culture, my country, my religion,
            my political party, nor my employer, but for me alone.