Possible to wire up power button without front logic panel?

[sickr1rider]

I bought and early 2008 mac pro case. I am putting in a gigabyte p35-ds4 (yes the dremmel and jb weld has been used : )

Anyway the case I got only has the power button with no front panel logic board. The button does have four wires that go to a very small connector.

Am I going to have to buy the logic board on ebay to make the power button work or is there something else I can do.

I could honestly care less about the front usbs and such. Its going to be in the floor and I have usbs on my monitor but I would love for the power button to work. I am sorry if this is a total noob question but this is my first ever case mod.

Thanks in advance

 

[humph]

The ones I've seen had 3 wires - perhaps that's the later version?
Anyway, I guess that two are for power button and other two for LED light.

Hopefully someone else can be precise, but failing that, should be easy to figure out if you can grab a multimeter (ohms) and check all the (6?) combinations of connecting 2 wires to see which results in connection (zero-ohms) when the button is pressed.

Also, check using multimeter if any wires are connected to "ground" (the metal button itself); if so, be sure to use that one of the identified button pair to connect to the "ground" (GND/0V) of the respective power-on pins on the motherboard's front panel connector.

If the "spare" 2 wires are indeed for the light, then you can likely connect those to the power-on LED connections on the MB's front panel header. Polarity will matter. Provided neither of these wires is also connected to "ground", then it's safe to try each way - if no light then swop the wires over (i.e. reverse connection to power-on light pins).

 

[sickr1rider]

Please excuse me for my noobness. I do have a multimeter from working on old arcade machines. Should I clip off the small connector of the power button, strip the wires, and twist two of them together until i find the right combo that gets a 0 ohms reading? Will I even get a reading with no power plugged in anywhere?

Thanks in advance

 

[flatfoot]

I had my G5 case's front panel open a few days ago and I think that mini-plug on mine had 4 wires, too.

But anyway, basically, finding out which of the wires are 'shorted out' when the button is pressed and then connecting those two to your mobo's front panel power button + and - respectively should do the trick.

 

[minihack]

Pretty sure the middle is a common ground for the switch and the LED and that the outside wires are + power and LED positive connection .Not sure which is which, but using a multimeter to check which of the two pins shorts to the middle pin when the switch is pressed will tell you.
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My first guess would be R is the positive side of the switch, B is the ground and W is the LED positive side.

 

[sickr1rider]

Your right it is only 3 wires and they are labeled just as yours are. I did however manage to completely screw up : I was carful to cut off the small connector and barely strip the wires.

I have a digital multimeter and tried to get a 0 ohm reading when pressing the power button with 2 wires twisted together.

I had no luck so I thought I should strip them a little more and see if I wasn't just getting a bad connection.

I ended up pulling the top wire loose from the button Should I try to solder it back on or is it a lost cause and get another one on ebay for around $25?

That is what you were wanting me to do right? Twist top and middle together but black multimeter cable on metal case, put red multimeter cable on twisted wires and then press the power button and it should read 0hm instead of 1? I tried all 3 combos of twisted wires.

Thanks for any advice, I believe I may be in over my head.

 

[minihack]

Your right it is only 3 wires and they are labeled just as yours are. I did however manage to completely screw up : I was carful to cut off the small connector and barely strip the wires.

I have a digital multimeter and tried to get a 0 ohm reading when pressing the power button with 2 wires twisted together.

I had no luck so I thought I should strip them a little more and see if I wasn't just getting a bad connection.

I ended up pulling the top wire loose from the button Should I try to solder it back on or is it a lost cause and get another one on ebay for around $25?

That is what you were wanting me to do right? Twist top and middle together but black multimeter cable on metal case, put red multimeter cable on twisted wires and then press the power button and it should read 0hm instead of 1? I tried all 3 combos of twisted wires.

Thanks for any advice, I believe I may be in over my head.

No.

How you work a multimeter is you put one terminal (e.g. black lead) of your multimeter on one lead from the circuit board (for instance the middle one), the other terminal (e.g. red one) of your multimeter onto a second lead of the circuit board. Make sure the multimeter is set for "Ohms" or "resistance" and check the resistance. The resistance should be high (i.e. off the scale) when the button is not pushed and zero when the button is pushed. When you have found the pair of leads on the board that exhibit that behaviour you have found which ones are the switch. As I said I am pretty sure the middle lead is the "negative" side of the switch.

 

[sickr1rider]

Ok thanks again, I am sorry I am such a noob but I guess we all have to start somewhere. Do you think I could solder the wire back or just buy a whole new button? I have soldered before but only a couple times. Guess its worth a shot?

 

[minihack]

Ok thanks again, I am sorry I am such a noob but I guess we all have to start somewhere. Do you think I could solder the wire back or just buy a whole new button? I have soldered before but only a couple times. Guess its worth a shot?

You have nothing to lose.

Make sure the soldering iron is up to heat. First apply solder to the end of the wire to "tin" the bare end, then using your three hands (!), put the tinned end of the wire onto the tab of the pcb and apply the soldering iron, adding solder if needed.

Practice first on an old circuit board until you get an idea of when/how solder melts.....

I am sure too there will be youtube videos etc. on how to solder that you can watc before jumping in.

 

[humph]

I ended up pulling the top wire loose from the button...

Oops! Glad to see others have dived in with better explanations than mine.

Re-soldering wire(s) should be no problem. Only thing to be aware of is to avoid excessive heat transfer, meaning don't hold the soldering iron on the solder pad, on the back of the switch, for too long - just enough to get a good solder connection - else you might cause the solder pad to lift off the PCB (by "melting" the glue that holds the PCB together etc) or damage the internals of the switch.

If it all goes well, perhaps it might be nice re-solder all connections with new wires, longer, right connector on the other end, etc