kmcvay@oneb.UUCP (Ken McVay) (07/07/90)
The machine: An early 10MHz 286 "baby at" stuffed into an XT case.
DOS: MS-DOS 3.3
History: 18 months' operation without flaw, running 40-meg hd, 360k fd, internal
2400 modem, ega and 1024k from 135w power supply. This was used as a mail
system, running FrontDoor, and ran 24-hours a day for about 18 months.
Portents: the owner decided to upgrade the box, and added an Everex RAM3000
board with a meg on it, a 1.44 meg 3.5" fd, and a second 40-meg hd. Poof.
Power supply apparently fails, and is replaced with 200w. Still won't work.
Replace HD controller (NCL 2:1 16-Bit) with another one, still won't work.
Replaced power supply with another 200w......
In other words, your average nightmare. ...in the course of playing with the
system, I first removed the RAM card, modem and IO card, leaving nothing but
the hd, fd, video, and controller. The drive booted and tested for 90
minutes without error....the test involved looping through a batch file that
worked the hell out of the disk, ran Vopt, NDD, chkdsk/f, Vmarkbad, etc. and
then looped and did it again. No errors whatsoever.
So, convinced the drive and controller were ok, I powered-down and put the RAM
card in. Tried to boot, but got "INVALID OR MISSING COMMAND.COM"
Removed RAM card, rebooted from floppy, copied new command.com from dos dir
to \ and rebooted....no sweat.
Inserted RAM card.....same error, except this time I couldn't reboot, even
after replacing command.com. It was as if track zero itself had been zapped.
Removed RAM card, rebooted, low-levelled the disk with Disk Manager and
MS-DOS 4.01 - but the systems BIOS now says "HIT A KEY TO REBOOT" and
will not boot.
It appears as if the motherboard may be flawed, and perhaps zaps the power
supply or drains it to the point where the disk can't turn fast enough to
be properly read....I have no idea, although I will soon test the drive and
controller in another box to see what happens.....if anyone has any
suggestions (other than "scrap motherboard and power supply and begin again")
I'd love to hear them - always did enjoy a good mystery....
btw - the owner ordered a new 386, but I want to know WHY this sucker fails
like it does before I bury it.
cheers/knm
--
1B Systems Management Limited, Nanaimo, British Columbia | kmcvay@oneb.uucp
Canadian Distributor: FrontDoor Automated Mail Systemsroy@cs.umn.edu (Roy M. Silvernail) (07/07/90)
kmcvay@oneb.UUCP (Ken McVay) writes: > The machine: An early 10MHz 286 "baby at" stuffed into an XT case. > DOS: MS-DOS 3.3 >[...] > Portents: the owner decided to upgrade the box, and added an Everex RAM3000 > board with a meg on it, a 1.44 meg 3.5" fd, and a second 40-meg hd. Poof. >[...] > ...in the course of playing with the > system, I first removed the RAM card, modem and IO card, leaving nothing but > the hd, fd, video, and controller. The drive booted and tested for 90 > minutes without error.... This is your red flag! (I shan't quote the remainder of your message...:-) You indicate that the machine would once again operate, after removing the RAM card, so I suspect the RAM card is FUBAR. As for re-formatting with DOS 4.01, I don't know what the conflict might be. Will the machine boot (without the RAM card) from a DOS 3.3 floppy? If so, re-init the HD with DOS 3.3, and scrap the RAM card. Also, did you test the power supplies you assumed to be fried? My 165w supply will not do anything at all (not even spin the fan) unless loaded. A floppy drive is enough to do it, but with no load it appears completely dead _even to a voltmeter_. > btw - the owner ordered a new 386, but I want to know WHY this sucker fails > like it does before I bury it. Don't bury it... send it to me! <grin> -- Roy M. Silvernail | 'I don't see why you people | Opinions found now available at: | seem to think this is magic... | herein are mine, cybrspc!roy@cs.umn.edu | Its just this little chromium | but you can rent (cyberspace... be here!)| switch here...[click]' | them.