The system is a 80486 DX2/66, 24 megs memory, running Win95 OSR2.  There
is a  single on board IDE connector.  HD is a  240 meg Samsung connected
as master with a Mitsumi CD-Rom as slave.  Because of a fan failure in
the 230W power supply, I replaced it with a similar 230W unit labeled as
a "PS/2 generic".  It had the same form factor and connections as the
original with the exception of a single two wire connector, possibly for
an LED or the cpu fan, which I did not connect,  and a chasis ground
wire, which I connected

Following the power supply transplant, got a disk error on the boot,
forcing a Drive A: boot with a rescue disk. Unable to access the hard
drive or the CD-Rom.  Drive A and the Zip drive worked normally with the
Zip drive assigned letter C instead of E.

Did the following trouble shoot:
        1. Ensured solid connections of the IDE cable, and checked
correct pin 1 orientation at all components.  No skipped pins, no bent
pins.
        2. Checked correct CMOS configuration for HD.
        3. Used CMOS HD autodetect...no drive found.
        4. Reset CMOS using BIOS defaults and power on defaults.  Still
no detection of the HD.  Restored original CMOS settings.
        5. Removed the hard drive from the CMOS, disconnected the HD
from both the IDE and power supply, reconfigured the CDROM as master,
plugged it into the IDE connector previously used by HD and rebooted
with the rescue disk.  The CD-Rom was not detected by config.sys or
autoexec.bat.  Not detected by DOS 7.
        6. Purchased a new 2 drive IDE ribbon cable, installed and
repeated above.  Still no detection of HD or CDRom as slave or master.

Note that my rescue disk has been previously tested with successful
access of all the drives (A,C,D,E).  Also the drive lights for both the
HD and CDROM are operating and the  CDROM drawer motor works.

My problem seems to be an isolated failure of the on board IDE system or
simultaneous HD and CDRom failures.  Doubtful, unless caused by the new
power supply.

As the next step I will briefly install the old power supply.  I will be
surprised if this makes a difference.  After that I am faced with a
motherboard replacement (an upgrade opportunity!) or a hard drive
replacement which stands to be unsuccessful if I am right about the
motherboard.

Any thoughts or suggestions will be welcomed.  Is the power supply the
culprit?  Is the MB wrecked?  By the way, the ps fan works fine.

Tim Peterson
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