Path: utzoo!utgpu!watmath!uunet!portal!cup.portal.com!thad From: thad@cup.portal.com (Thad P Floryan) Newsgroups: unix-pc.general Subject: Re: Random HDERRs Message-ID: <11944@cup.portal.com> Date: 30 Nov 88 08:46:35 GMT References: <447@manta.pha.pa.us> Distribution: unix-pc Organization: The Portal System (TM) Lines: 30 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@cup.portal.com (OR) ...!sun!portal!cup.portal.com!thad]