Power Switch/LED wiring question

[spence4]

I have a wiring question for my electrically gifted friends out there - (Minihack, Neilhart, ersterhernd, and Mactest57 I'm looking at you guys). I have recently purchased a hard drive enclosure that I think would make a nice home for my NUC. The power button to turn the thing on only has three wires though: black, red, and green. When I plug black and red into the power on/off header of my NUC, it turns the NUC on and off - easy as cake. However, when I add the green wire and connect it to either the + or - of the power LED header the light is on when the computer is off and when I turn on the computer the light either stays on, or turns off - not a piece of pie. Obviously the situation where the light is on when the computer is off and turns off when the computer is on seems to be closer to what I want as it has two states for the light rather than the "always on" state of the alternative. Anyone have any suggestions?

The push button switch and LED are housed in a plastic contraption that would require the snapping of plastic to see what is going on inside. Outside the plastic, on the little PCB there is "LED" written next to the green wire termination, and I just assumed that the red and black writes were the normal red and black wires of a power switch.

Appreciate any help people have.

Thanks.

 

[neilhart]

Spence - I would use an ohm meter and not your NUC to map the switch/LED. It sounds like your assumption of which wires are the switch is not correct.

Normally the motherboard power switch header pins have +5 VDC pullup power on the "+" pin and DC common on the "-" pin. On the power LED header pins, the "+" is a floating no voltage level until the motherboard puts 5 VDC on to it. The LED header "-" pin is normally DC common.

Your observation that the LED is on all of the time leads me to think that you have the anode of the LED connected to the power header + 5DVC pin.

Good modding,
neil

 

[spence4]

Neil,

Thanks for the quick reply. Turns out you were absolutely right. I had the black and red wires going to the wrong pins. I didn't realize this at first because pushing the power button still turned on the NUC (obviously this will always be the case because the two pins are momentarily connected) However after switching those two, I now have the leftover green wire going to one of the LED pins which gives me the accurate indicator for the state of the NUC (light on=computer on; light off=computer off). Unfortunately, it is a red light which doesn't really fit with the whole Apple thing. The light was showing blue before which I think is nicer, but still not as good as white. As I mentioned before, I'm a little weary of snapping the plastic to swap out LEDs.

Thanks again for clearing up my problem. Knew I could count on you.

Take it easy,
SPence

 

[rkwallace]

Neil,

Thanks for the quick reply. Turns out you were absolutely right. I had the black and red wires going to the wrong pins. I didn't realize this at first because pushing the power button still turned on the NUC (obviously this will always be the case because the two pins are momentarily connected) However after switching those two, I now have the leftover green wire going to one of the LED pins which gives me the accurate indicator for the state of the NUC (light on=computer on; light off=computer off). Unfortunately, it is a red light which doesn't really fit with the whole Apple thing. The light was showing blue before which I think is nicer, but still not as good as white. As I mentioned before, I'm a little weary of snapping the plastic to swap out LEDs.

Thanks again for clearing up my problem. Knew I could count on you.

Take it easy,
SPence

Can you post info or a diagram on which pins you have the wires connected.

From your pics I assume the green wire is connected to pin #4, red to pin #6, and black to pin #8. Am I correct?

Thanks Robin