A little background to my question: I got a laptop some time ago from my grandparents because the screen was broken and they didn't want to fix it. Being your typical tech geek, I already have a laptop and a more powerful desktop, so I decided to take the motherboard, hard drive, etc. out of the laptop and make it into a small media box to hook into a TV. Wanting to give the front a nice, clean look, I got an LED-lit N.O. momentary switch for the front to switch the power on/off, and I was hoping to wire it in parallel with the laptop's current power switch, taking it out of the loop so to speak.

I'm now looking at the power switch used in the laptop, and I'm not sure where, or if, I can hook wires to it. Here are some pictures:Top side, switch located lower left. Top side, switch located lower left.Bottom side, switch located lower right. Bottom side, switch located lower right.

I was wondering if anyone was familiar with this type of switch or had suggestions for testing where the actual switching contacts are? I've taken a multimeter with a resistance test to various pairs of contacts and couldn't find any difference when the button was pressed.

I'm also open to other suggestions for controlling the power from the switch in the front of my new box.

  • \$\begingroup\$ Looks like a normal run of the mill pulse button. 4 obvious pins are the metal shield to prevent it coming from the board. 2 more contacts that become a pulse-make contact will be below or at the back of the switch. May be connected to the transistor on the bottom through a via. In fact I think I can see one of the two connect to ground on the transistor side. But these pictures might have been much less fuzzy given better light and actual in-focus-ness \$\endgroup\$
    – Asmyldof
    Mar 28, 2016 at 23:49
  • \$\begingroup\$ can you use a multimeter and press the button and probe while doing continuity/beep test? \$\endgroup\$
    – Wesley Lee
    Mar 28, 2016 at 23:52

1 Answer 1


You really need at least a basic meter to confirm which pins are which. There are four pins coming out of the switch, two on each side. This is a SMD (Surface Mount Device) and the same pins that hold the switch on to the board are also the electrical connections. There are several possible different configurations that the switch could be. With even a $5 budget DMM you could probe various combinations of pins to confirm which ones connect together when you activate the switch. Then you can solder wires from your added witch across the existing switch.

There is some likelyhood that the two pins on the button side of the switch are connected together as are the two on the rear. And then when you activate the switch the two pins on the front connect to the two pins on the back. For example see the data sheet:



  • \$\begingroup\$ Thanks, Richard. I knew it was an SMD since it didn't appear to have thru pins to the bottom (though as Asmyldof pointed out, they could have been located under it), but I didn't have the first clue of where to look for a data sheet. When I checked the first time, I just looked at the pins going across the switch not front to back. Checked again, went from infinite to negligible resistance from front to back pins when the button was pressed. Problem solved. \$\endgroup\$
    – dboston
    Mar 29, 2016 at 0:24

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