Archived from groups: alt.comp.hardware.homebuilt (
More info?)
On 10 Mar 2005 22:16:33 -0500,
MRGiam@hotmail-dot-com.no-spam.invalid (MRGiam) wrote:
>How do you count the pins...? (there are no markings.) I have the same
>MB and the same trouble. By the way, the On_Off pin should be pulled
>down (grounded) or pulled up (+v)??
>
>I am about to trash the board... I won't come up...
>
>M
Pin 1 is usually in the top left corner, all you have to do
is figure out which is the top left corner. Often there is
a little silkscreened arrow or other marking for pin 1.
The easiest way to determine pinouts on these OEM boards is
to look at the OEM wiring harness that was used with it.
That "must" go to the front LEDs, switches, etc, so a simple
continuity check with a multimeter will reveal which pins
are which.
An alternate method for those ambitious would be to take a
resistor, say 100 ohm, and touch it very briefly to each pin
with the other end grounded. When touching the pin that
turns system on, you then only need check the other pins
(start with those adjacent) to find the ground. Ground plus
that pin will go to the switch. It is possible the OEM only
used one or two ground pins rather than a ground for each
front panel "component" (like LEDs, switches, etc), in which
case you'd need to split the ground into several leads to go
to each component, unless of course you still have that OEM
wiring harness and connectors and/or circuit board, then do
whatever seems appropriate per the new case.
Frankly it's easier to just reuse same OEM case and wiring
instead of redoing it all.