barber@applga.aa.cad.slb.com (Steve Barber) (07/19/90)
Well, last night was bad news. A lightning storm was coming
into the area so I shut down shade, my 3b1. Since I knew
his insides hadn't been cleaned in a while, and I had a battery
sitting around waiting to be installed the next time I had
the time and the opportunity, I pulled him all apart, cleaned
the (literally) mounds of cat fur and dust off the motherboard
and power supply, and replaced the battery with a coin-type
battery holder. (With battery, of course!)
The humidity was high, so I wasn't too worried about static.
Well, looks like I got bit anyway. On power up, I got the screen
full of bit patterns, then a clear screen for a split second, then
a screen of alternating all on/all off words, where it hung.
(i.e.: xxxxx xxxxx xxxxx xxxxx
xxxxx xxxxx xxxxx xxxxx
xxxxx xxxxx xxxxx xxxxx
(etc.)
)
The LED pattern was: Red: ON
Green: off
Yellow: ON
Red: off
which a friend with the reference manual tells me is the code for
bad motherboard memory.
Now, I have 2Mb of motherboard memory, and I'm almost positive it
is not socketed. I have a couple of spare 41256 RAM chips, but
desoldering all those chips does not thrill me, and even then I
have no idea which chip is bad. (If I *were* to go and pull all
those chips, I'd most definitely stuff sockets in there...)
My friend suggested that AT&T had some diagnostic EPROMs that
would locate the bad chip. I seem to recall that people on the
net had not been able to find these EPROMs in the past though.
Then I thought I'd write and burn my own diag eproms to find
the bad chip, until I realized that I had lost my assembler and
linker setup for the EPROM programmer when I lost shade.
So. Does anybody have any suggestions? I *have* to get this
fixed, and cheaply. (I'm a student who needs a working computer
next fall, but can't afford to go back to school if I spend
much money getting this fixed!)
Those of you with worthwhile suggestions, please send e-mail to me
at: barber@applga.aa.cad.slb.com. I'll try to monitor these
groups from work, but I might miss something, so e-mail is best.
Thanks a million,
Steve
--
Steve Barber, Schlumberger CAD/CAM, Ann Arbor, Michigan
Work: barber@applga.aa.cad.slb.com (313) 995-6000
Home: steveb@shade.ann-arbor.mi.us (313) 665-0884