Random HDERRs

[Thad P Floryan]

Re: Brant's "random" HD errs, check your power supply's voltages.

Don't laugh.

I've seen UNIXpc's whose "+12VDC" was actually +10.53VDC, and the HD error
symtoms are/were IDENTICAL to those you describe.

There is a labelled "+12 V Adjust" potentiometer (and a +5 and -12 (unlabelled)
on the UNIXpc's power supply.

The easiest and most reliable way to adjust the voltage is to get one of those
disk-drive power "Y" cables (probably $1 to $2) and have everything connected
AND your digital VM's probes into the 3rd connector while making the adjustment

Turning the +12 pot clockwise increases the voltage; be SURE to use a plastic
non-conducting tool for making the adjustment (in case you sneeze and/or
drop the tool into the power supply!  :-)

I've found that adjusting to slightly OVER the 12 volt mark is a wise move
(I set mine (4 systems) to between 12.15 and 12.20 VDC)

5% of the 5VDC is  5.25V to 4.75V

5% of the 12VDC is 12.60V to 11.40V

Would STRONGLY suggest doing a file backup BEFORE the voltage adjustments, esp
if the adjustment alters the performance slightly (which I HAVE found to be so)


Thad Floryan [thad at cup.portal.com (OR) ...!sun!portal!cup.portal.com!thad]