P8
1 Orange PwrGood
2 Red +5Vdc
3 Yellow +12Vdc
4 Blue -12Vdc
5 Black Gnd
6 Black Gnd
P9
1 Black Gnd
2 Black Gnd
3 White -5 Vdc
4 Red +5Vdc
5 Red +5Vdc
6 Red +5Vdc

"The only discrete "signal" in the AT-style power connector is the Power
Good (Pwr-Good
or PG) signal. This signal is typically tied to the CPU's Reset pin. When
the PC is
first powered up, this signal is logic 0 and the CPU is forced into a
continuous reset mode.
After the power supply is stable (usually about 0.5 seconds from the time
you flip the
power switch), this signal rises to a logic 1. This releases the Reset, and
the CPU can be-gin
processing, which starts the boot process.".... So, power good must be +5v
to make the system work...


Alberto Stapelfeld.



----- Original Message -----
From: Wayne Harris <[log in to unmask]>
To: <[log in to unmask]>
Sent: Friday, January 28, 2000 7:19 PM
Subject: Computer not posting


>     Good evening. I have a problem with a computer not POSTing. It is a
> 486/66, and /or a Pentium 166 (I have 2 motherboards) I originally was
going
> to upgrade to the 166, but ran into problems.
>     The 166 tested out fine with just the motherboard, 166 chip, 32M of
RAM,
> and a video card attached to an extra power supply (no OS). It posted fine
> and I got a display on the monitor. The hard drive spun up and it sought
the
> floppy drive ok. That was as far as I had tested it.
>     I then tried to install it into my AT case. I did not get a post, I
did
> not get a monitor display, the hard drive spun up, and it sought out the
> floppy. I tested another known working monitor and it still didn't
display.
> I replaced the 166 motherboard with the 486/66 motherboard  (and another
> video card) and it did the same thing. A note to say that when I
> disconnected the video cable from the video cards,   I did get a raster
(on
> both of the monitors).
>     My next step was to drag the motherboards out of the case, in case
there
> were any shorts, and still got the same thing on each motherboard.
>     The only things I seem to be left with are bad P8/P9 connector
voltages,
> or bad RAM. I can't believe that both motherboard RAMs are bad,  so I
> suspect the plugs are bad. I can't get to a meter until next Monday, so I
> was wondering if anybody out there had any ideas of anything else I could
> try before next Monday rolled around.  Also does anybody know the voltages
> from the P8/P9, and what pins have what?
>                                                 Thanks Wayne Harris
>
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