Troubleshooting the power button

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tmn313

I have put together all of the components for my new PC. The power LED on
the motherboard is on when I plug it in, so I know power is going to the
board, but when I press the power switch, nothing happens. I've verified the
cable from the button is connected to the board per the instructions and all
of the drive connections and cards are secure and the fans are all plugged
in. Where do I start troubleshooting? The system specs are below:

Antec Plus660AMG case
Ansus P4P800 Deluxe
Intel P4 2.6Gz
Seagate 80GB drive connected to primary IDE slot on board and set to cable
select
Western Digital 180GB drive connected to the PCI controller it came with and
set to cable select
DVD drive from my old PC connected to the secondary IDE slot on the board
and set to cable select
3.5" floppy, additional USB2 card
 
When your putting a new system together it is best,IMO, to start booting with the bare minimums. PSU,MB,CPU,MEM,VID. Then add on a
couple at a time or all the rest if you prefer. For now, nothing happens as in no beep, no cpu fan? Your case has a 'case speaker'?
Memory is in the correct slot(s)? reseat the CPU, did you have any problems when you closed the lever? the IDE cables are in wrong.
All guesses as you know... hope you get it.
 
tmn313 said:
I have put together all of the components for my new PC. The power LED on
the motherboard is on when I plug it in, so I know power is going to the
board, but when I press the power switch, nothing happens. I've verified the
cable from the button is connected to the board per the instructions and all
of the drive connections and cards are secure and the fans are all plugged
in. Where do I start troubleshooting? The system specs are below:

[...snip]

To test the ATX PSU:

First, disconnect everything from the power supply (including MB.) Plug
AC cord into the rear of the PS. IF the PS has its own rocker on/off
switch, turn it ON. There should be +5v on pin 9 of the 20 pin connector
(+5vsb, usually a violet wire.) There should be >0.8v on pin 14 (PS-ON,
usually a green wire.) This is from an internal pull-up to the +5vsb.

Connect PS power leads to 1 or 2 IDE HDs (for a load). Jumper pin 14
(PS-ON) to pin 13 (ground, black wire.) At this point, fan in PS should
start spinning, drives should spin, and + 5/12v, -5/12v, +3.3v, and
+5vsb should be present at 20 pin connector.

Disconnecting pin 14-13 jumper should turn supply back off.

Further:

When your system fails to start, what is the voltage on pin 9? If it is
less than 4.75v, either a) the logic on your motherboard is shorting
b) your +5vsb is under powered, or c) your PS is bad. It is
most likely a combination of b) and c).

If your +5vsb is OK, measure pin 14 of the PS/MB connector. If it is <0.8v
(and the +5vsb is OK), the power supply should be on. If pin 14 is <0.8v,
the +5vsb is OK, and the PS is OFF, the PS is bad. If pin 14 is >2.0v, the
power supply is being told to stay OFF by the MB. If depressing the front
panel ON/OFF switch does NOT lower pin 14 to <0.8v (and the +5vsb is OK),
then the problem is NOT the power supply, but rather MB related.
 
Got it fixed - started by unplugging everything but the motherboard and
using Antec's instructions on how to test the power supply - led to
discovering that the power switch connections were off by 1 pin on the
board! Thanks for the pointers.
 
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