How to find Power SW on my Motherboard for external power button?

[maks]

Hey guys,

I recently picked up an Alienware Alpha and have mame setup in it. Its going inside a cabinet and will need a power button. Problem is that I can't find the Power SW cable. All I see is a 12 pin connector attached to Alien_Head with 11 black wires coming out of it. Motherboard doesn't name each connection either. I think the rest of the wires are for LED lights.

There's no motherboard manual and I checked the 87pg Alienware Alpha Service Manual on Dells site but still can't find a schematic for these pins. Is there another way to find Power SW???

[behrmr]

Trace the wire from the switch to the header.

[Warborg]

Well, it might have some risk but I've done it several times and not had a problem...  With the system already off, go along with a flat head screwdriver and bridge a couple pins at a time until it powers up.  Theoretically as it's off there should be no power going to that header's LEDs pins so shouldn't be a problem with dead shorts, so just tap a couple pins at a time until it powers up.

[yotsuya]

Well, it might have some risk but I've done it several times and not had a problem...  With the system already off, go along with a flat head screwdriver and bridge a couple pins at a time until it powers up.  Theoretically as it's off there should be no power going to that header's LEDs pins so shouldn't be a problem with dead shorts, so just tap a couple pins at a time until it powers up.

Yep. This.

[nitrogen_widget]

Well, it might have some risk but I've done it several times and not had a problem...  With the system already off, go along with a flat head screwdriver and bridge a couple pins at a time until it powers up.  Theoretically as it's off there should be no power going to that header's LEDs pins so shouldn't be a problem with dead shorts, so just tap a couple pins at a time until it powers up.

haha.
My favorite method of turning on every motherboard I get my hands on that is no longer in the case.

[yotsuya]

What I've found more often than not is that the front panel connector is usually a 10 pin one, and the power switch posts are usually the two next to the missing pin on the 10 pin header. What's nice is most of the newer boards I've worked with color code these pins red.

[maks]

Thanks so much guys I'm going to try the bridge method. I was curious if it would be safe to do so. If i get this done my cabinet would be near complete. I'll update when i find it.

[heykool69]

Well, it might have some risk but I've done it several times and not had a problem...  With the system already off, go along with a flat head screwdriver and bridge a couple pins at a time until it powers up.  Theoretically as it's off there should be no power going to that header's LEDs pins so shouldn't be a problem with dead shorts, so just tap a couple pins at a time until it powers up.

hahaha......I used to use this method years ago.  I'm glad i'm not the only one.  And my co-workers called it "ghetto" style.

[deano71]

Im going to run my power button from the top of the cabinet. Can you tell me what type of cable I would need and will a standard arcade control push button work?

[blacketj]

Yes, an arcade button will work.  And you can use the same type of wire you will be using for your other buttons.
You might want to hide the Power button on the back side of the cab or under the control panel. You don't want it to get hit accidentally during game play.

[05SRT4]

The old flat head bridge is what I usually do but.....

I just recently worked on an old Dell XPS 400 and the pin out for the front panel is like a 30 pin connector. I was not able to find the actual pins needed.

So I just kept the front panel board connected and just soldered wires to the actual power button. On the bottom of the front panel board it was super easy to find where I needed to solder.

If you can find the pins then use a JST Connector then a normal arcade button on the other end. Keeping it away from edges and the top. People tend to rest their arms up high and press it on accident.

[maks]

Got it on the first try. Went to a local hobby shop and found a JST connector for $2.50. Had to shave it down on the sides to fit in my motherboard. It was indeed right next to where the missing wire was.

Thanks so much guys. Now i gotta get a power button.

[jeremymtc]

Awesome, Maks.

Anecdotally (I think I just made up that word), I remember one time I was screwdriver probing a mobo for the power pins, got a bootup and proceeded to wire my switch and assemble. Darndest thing though, was after finishing it the system would just boot up and immediately shut down again. Removed and reinstalled the RAM a couple of times, re-seated the CPU a couple of times, and then realized that I had isolated the reset switch pins by mistake

[qnology]

Hello @jeremymtc,

Apologies for replying to a old thread but I also have an Alienware Alpha R1 which I'm looking to use in a bartop arcade.

Thank you for identifying the power sw pins on the motherboard.

Using the power sw pins you identified, I'm able to power on the computer just fine, but unable to power off the computer using the same switch (arcade button). However, if I plug back in the original switch, the computer power off just fine.

Any ideas? Did you have a similar issue? Thank you.

[Drnick]

Hello @jeremymtc,

Apologies for replying to a old thread but I also have an Alienware Alpha R1 which I'm looking to use in a bartop arcade.

Thank you for identifying the power sw pins on the motherboard.

Using the power sw pins you identified, I'm able to power on the computer just fine, but unable to power off the computer using the same switch (arcade button). However, if I plug back in the original switch, the computer power off just fine.

Any ideas? Did you have a similar issue? Thank you.

Have you set the system to shut down when power button pressed?  Default would be do nothing.  If you hold switch in for 5 seconds does it power down.  If so look for power settings and set the option for power switch to shut down when pressed.

[ChronosWing]

Hello @jeremymtc,

Apologies for replying to a old thread but I also have an Alienware Alpha R1 which I'm looking to use in a bartop arcade.

Thank you for identifying the power sw pins on the motherboard.

Using the power sw pins you identified, I'm able to power on the computer just fine, but unable to power off the computer using the same switch (arcade button). However, if I plug back in the original switch, the computer power off just fine.

Any ideas? Did you have a similar issue? Thank you.

Having this same problem... everything in windows is set correctly, computer will boot from off and from standby with the button but will not sleep or shutdown no matter the setting. My temporary fix which may become permanent was to splice in another JST connector to one of my encoders and use autohotkey sleep script. Now pushing the  button puts the computer to sleep and pushing again wakes it, also it doubles as the power on button if the computer loses power. Wish I knew what the real issue was though so I didn’t have to macgyver it.