G5 front panel question

[Gus]

Use this. Only need to connect pin 2, 9, 10, 11, 12, 13, 14. Connect pin 2 to any Mobo ground.

 

[Gus]

Pin 2 to any ground. Either Power Led Ground(-), or Power Switch Ground(-).
Pin 13 to Power Led Positive (+).
Pin 14 to Power Switch Positive (+).
Pinout

 

[chaosdesigns]

I have a question. Where on a motherboard do I connect the +25V Firewire connection (Pin 1)? My power supply is a "single rail 12V".

 

[Gus]

I have a question. Where on a motherboard do I connect the +25V Firewire connection (Pin 1)? My power supply is a "single rail 12V".

If you find a pinout of a Firewire header, you will see it has pin 7 and pin 8 as +12V. So simply connect these together to get your Apple pin 1 +25V.

PS It does not matter that it is 1V less.

 

[chaosdesigns]

Thanks, Gus.

My worry is that once you connect the two 12V supplies together; wont they feed back on each other into the MB? Would installing a diode on each supply before connecting them be a better idea? That way the diodes would prevent each of the supplies from back feeding. And I believe the voltage drop would be negligible.

One other thing... I examined my Corsair 850D wiring harness as it includes firewire on the front panel. It's 1394 motherboard header only connects to one of the 12V pins, the other is not connected, yet the port is fully functional.

Your thoughts?

 

[nikstar]

You do not have to put a diode on those 12v supplies.

Your harness is probably connected to the motherboard header at one of the 12v pins but it should be split it at the other side at the both of those pins.
Is probably like this for money saving. Less cables.

 

[Gus]

As mentioned above. I wouldn't bother putting on diodes. I have never even thought about this. And I used to make and sell those front panel harness' hence why I can so easily tell you what to do. Eelhead has been using one of my cables from the very begging of his G5 career. And it was made by mating both the +12V firewire header pins and joining them to the single +25V pin on the apple pcb. And to my knowledge he nor anyone else has had any problems with the that set up.

 

[nikstar]

I am saying that is not necessary to put diodes at the power lines but also it will not harm if you put one.
I make my own G5 front panel without diodes and is working perfect for about a year and a half.

 

[chaosdesigns]

Thanks for the info. I will attempt it. It was just my electronics education back in grade school that said when the 2 are connected, then anywhere along that connection it would measure 24V, So I was worried that the mobo may not like that.

 

[nikstar]

Actually there is nowhere 24v, it could be like you said if you are using two different power supplies. In your case the two 12v lines are providing more power (amps) not voltage.