Voltages on older PCs

Julian Stacey jhs at berklix.org
Thu Jul 24 13:47:27 UTC 2008

Hi hardware@ (cc Gary & Michael)
Comment welcome before I return a FreeBSD-7.0 host to service, 
	(taken away for analysis after it fell off line a few times).

I've long since rebuilt world, (still 7.0-REL), & built a few needed
ports/, but much reduced ports/ than before, Many less auto start
processes load from local/etc/rc.d & especially, no mailman, (cos
I've seen thrashing from mailman on FreeBSD before).

I'd checked temps long since too, with a real probe, not BIOS, they're OK
(& the normal remote site has good power & very cool )

Checked Volts last night (Yes AT style 2 adjacent 6 pin connectors):
	PIN             COLOUR  NOMINAL Slim    Test
	P9.[4-6]        Red     +5      +5.14V  +5~
	P9.3            Green   -5      +0.282V -5~
	P8.[56] P9.[12] Black   0       -       -
	P8.4            Blue    -12     -11.94V 0.56
	P8.3            Yellow  +12     +11.9V  +12.3
	P8.2            Purple  +5      +5.11V  +5
	P8.1            Grey    ?       +2.4V   +5

 	P8.1:	OTS book says: "Power Good" but no V. is specified.
 	Slim:	The remote server in question
 	Test: 	For comparison: Open frame pentium I test cards with.

I recall some old PCs needed an extra negative (-5 or -12 ?), for
RAM refresh, (& another also -12 for proper RS232, though rarely
if ever did PCs use more than 0/5 on cua/tty, thus not Real RS232),
but that some negatives got abandoned on some m. boards as no longer
needed (I think refresh requirements changed).

Curious thing is these 2 boards both run, but with different low
voltage pins. Can anyone cast insight ? If not, I'm inclined to
shrug & return server to service (where it's largely a backup anyway,
not domain critical).

Thanks for any insight,
Julian Stacey: BSDUnixLinux C Prog Admin SysEng Consult Munich www.berklix.com
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