From: hybl@umbc4.umbc.edu (Dr. Albert Hybl (UMAB-BIOPHYS))
Subject:  More info about my troublesome 3b1
Organization: Univ. of MD, Baltimore County
Distribution: na
Date: Thu, 10 Sep 1992 21:40:17 GMT


This posting is in response to a mild scolding from a
respondent:  "It would have been nice to have an indication as
to which version of O.S. you are running.  (B.T.W. The [panic]
messages vary with the version of the O.S.)  Also, are you on a
7300 or a 3b1?  How much memory on the CPU card?  Any extra
memory?  Any other cards present?"

There are no cards in the expansion slots.  There is 2Mb of
memory on the motherboard.  I am running 3.51m.  The disk
cntr is WD1010 and the motherboard is P3...P5.  The machine
was sold to me as a 3b1.  It has the hump and a full height
HD with 67 Mb of memory.  The power supply is Model PS 1569
that says it is a 7300 (3B1s use model PS 1610-1).  Reading
the FAQ description of the differences:

"The 7300 machines featured 512k RAM on the motherboard with a
10 or 20MB disk.  The later 3B1 machines had 1M or 2M on the
motherboard, and came with a 40 or 67MB disk. ... The 3B1 also
has a heftier power supply."  ARE THERE ANY OTHER DIFFERENCES
BETWEEN A CPU MOTHERBOARD OF A 3B1 AND A 7300 BESIDES THE AMOUNT
OF MEMORY?  I assume not.

It seems that I have either an underpowered 3b1 or a memory enhanced
7300.  I plan to add a 2Mb memory expansion board and a STARLAN
board.  WILL THE PS-1569 POWER SUPPLY BE A PROBLEM?

Since my first post I have had several panic messages,
one with trap vector 11 followed by a "Double panic" with
trap vector 1 after which the system did not reboot
and the monitor only displayed the green screen:
--__--__--__--__--__   etc.to the end of a line 
--__--__--__--__--__
--__--__--__--__--__
--__--__--__--__--__
The lines on the screen are very close together and the pattern
fills the screen. (The -- are true lines not dashes.)
They could be called shallow square-wave patterns that fill the
whole window. 

I opened the machine again to expose the FD, HD and Power Supply
and noticed that the GREEN ground wire from the switch block
to the back corner of the power supply was held by a loose
screw!  It was not disconnected just loose.  I tighted that screw
then examined the other wires and cables.  The cable to the monitor
has an indentation caused by the HD and the screw that should hold
it to the frame on the left side was missing.  The other wires
look OK.

Without closing the machine, I reattached the keyboard and turned
the 3b1 on.  Two pencils separate the keyboard from the
metal platform where it would usually be when packed.
The monitor faces the ceiling with space allowed for
the fan to function.  THE MACHINE BOOTED AND HAS BEEN
RUNNING SINCE--ABOUT 40 CONTINUOUS HOURS SO FAR.  I have run
a number a tasks on the machine, including I/O via the floppy
drive.  I'll start running the diagnostic disk to test the
memory soon.

The metal plate below the keyboard is running warm.  The CPU
is surely just as hot as when the hood is closed.  The fan
seems to be working well and there was no indications of
overheating when the shell was closed.  This suggests that
it is probably not a temperature-sensitive problem.  It may
be related to a crimped cable or poor grounding.

The loose ground wire must have been like using a two prong
adaptor plug to defeat the grounding prong.  COULD or DOES
POOR GROUNDING CAUSE PANIC PROBLEMS?  COULD INTERMITTENT
CONTACT BETWEEN COMPUTER AND GROUND CAUSE PROBLEMS?

Thank you,
Albert Hybl (hybl@umbc3.umbc.edu)
Newsgroups: comp.sys.3b1