From: kushmer@bnlux1.bnl.gov (christopher kushmerick)
Subject: SUMMARY: Intermittant failures on 386/486 machines
Organization: Brookhaven National Laboratory
Distribution: na
Date: Sat, 2 Jan 1993 23:32:36 GMT

Last month I was seeking advice on how to fix my intermittant problems
on my relatively new 486-33. Many people responded. I am trying 
some of the ideas. I'll repost when I figur out what works best. 
Meanwhile here is the summary.

Here is the original post.

I have a 6 month old 486-DX-33 machine. I have used it a lot and so
it is safe to assume that it is "burned" in. But:

When it is on for a few hours, things (see below) go wrong that only 
seem to be fixable by turning off the computer for a while.

I am interested in how many owners of 486 machines have intermittent 
problems. Here are a few of what I get after the computer has been on
for a few hours


1) When I run word perfect, I get the message "packed file corrupt".
I am running from DOS, and I believe that this is a dos message.


2) windows progman gives access violations (or what ever they call it)
as reported by "application failure" report. This occurs during windows 
startup and I usually can not start windows

3) In the same time frame as 2), when I start window, the screen goes blank
and the computer hangs.

I try reset the computer, even power down/up but it does not help. the
only thing that helps is turning the power off for a few hours.


I long ago disabled smart drive, thinking that this may be the problem. 
It did not help.

Disk doctor reports nothing unusual (well actually there were a few lost chains
I don't know if this means I should reformat the disk and reload everything
or not... Any suggestions here).

SO please send me mail if you have intermittent problems on you new 486, or
if you did and figured out how to fix them. I'll summarize replies.

One obvious idea is insufficient ventilation. However this occurs as frequently
when the house is 65 F. as when it is 75F. degrees. the air coming out
of the (large tower) case is always cool to the touch, although I never
measured it. Perhaps the air is not circulating properly though the 
boards. I may try to put in a larger fan this week...


Please do reply (mail or post) if you have any ideas .

thanks,

-end of original article. Here are the replies

From: "Maoee Tsen" <tsen@chemsun.chem.umn.edu>
It look like that you have a over-heated element somewhere in your
system.  Try to run your system with case removed and see you can run
the system longer or not, if yes, then you need better ventilation in
your system.  You may consider buying a cooling device for your CPU,
there was an ad on the forsale newsgroup for $25 a few days ago,
Zeos also sell that for $25+$3(S/H).  Good luck!

-Maoee

From: t06@clark.edu (Torry Schreiner)

In article <1992Dec14.235952.10145@bnlux1.bnl.gov> you write:
>I try reset the computer, even power down/up but it does not help. the
>only thing that helps is turning the power off for a few hours.

I had the same sort of problem on a 286.  It turned out the power supply
was hurting and not giving my computer real clean power and then would
just die.  You might want to check out you power supply.

From: "M. Munoz" <mem28103@uxa.cso.uiuc.edu>

Well, how about reseating everything that can be reseated.  i.e. unplug
everything and plug them in tight.  This includes all connectors, ROM BIOS
chips (maybe just press down on it dont pull it out), SIMM's, power
connectors, boards.

Maybe try rearranging boards.  So that the video board is as far away
from everything else as possible.

Maybe try putting a CPU cooler on your 486 (get the clip on type).  Possibly
the chip is getting hot locally while the rest of the system stays
relatively cool.

Also, check all chips on expansion boards to make sure that they are 
well seated.

Make sure that any PKLite files are v1.14 or higher.  Use CHK4LITE.EXE
program (comes with PKLite).

Check for memory conflicts.  Try running off a bare AUTOEXEC.BAT
file and a CONFIG.SYS with only FILES=40.  Or remove all device
drivers but the main ones (e.g. himem.sys, emm386.exe, etc)

Make sure all of you DIP switches and jumpers are set properly.

Well, I can't think of anything else.  Good Luck

			-Marc

From: chodges@nswc-wo.nswc.navy.mil (Christopher Hodges)


Based on the sparse information I read, I could guess at a few solutions:

	- it's a bad chip, possibly the BIOS ROM

	- something's loose in there, again, possibly a chip

	- perhaps the power supply.  this gotcha is too often ignored.

From: the stupid one <warren@wam.umd.edu>
Message-Id: <199212151944.AA06514@rac3.wam.umd.edu>

for the lost chains: run chkdsk /f.
it will ask if you want to convert lost chains to files.  say yes.
when it exits, there will be a file[s] with wierd names (bunch of letters
and numbers) probably in the root directory of that drive.  delete them.

for the main problem: it might  indeed be a cooling problem, but a bigger
fan might not help.  as a test, try taking the case off and running the
machine with a room fan blowing on it, and see if it still acts wierd.


From: Gordon Edwards <gedwards@ncratl.atlantaga.NCR.COM>

>as reported by "application failure" report. This occurs during windows 
>startup and I usually can not start windows

I just upgraded my machine at work to a 486 33MHz DX and am getting these
same annoying application failure messages, but am only getting them in
a Dos Window right now, haven't gotten any yet inside other windows
programs.

I have a 386 40MHz machine at home with the same BIOS (maybe not the same
version) and have no problems with it.


From: ab245@cleveland.Freenet.Edu (Sam Latonia)

It sounds more like you have a bad opwer supply than anything else.
Get a can of FREEZE IT from Radio Shack and when the problem starts
power down the computer and spary the inside parts of the power supply
if the problem is resilved on repower up then you can iether replace
the hole power supply. Or start over again and only spray one
componute at a time till you find the bad part in the power supply.
Then just replace that bad part with a new one...Sam


From: Shane Hartman <shane@spr.com>


I had problems like this on a 486/33 everex.  I tried lots of things
too.  It still failed.  I dumped it and bought a gateway 486 66/DX2.
No more failures.  I have always suspected the bios.

However, I think your problem may be your keyboard controller (ref
article in byte magazine, forget the issue).  Older keyboard
controllers are called K-9, newer K-10.  What does the keyboard
controller have to do with anything?  It has the A20 gate which
controls access to extended memory in windows.  Try two things: If
your machine has an option called "Fast A20 gate" or something like
that in its bios setup, turn it on.  If not, When the machine boots,
it will put some numbers at the bottom of the screen (the bios ident).
If you see K-9 or K9 you probably have an older keyboard controller.
Call the manufacturer and see if you can get a K10 controller chip.


-- 
Chris Kushmerick
kushmer@bnlux1.bnl.gov
Newsgroups: comp.sys.ibm.pc.hardware