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Front panel question on Power Mac G5 18 pin


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#1
Flybye

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Hi all,

My motherboard doesn't have firewire. I bought a firewire card, but it only has the 6 port external connector on the pcb. The card came with an adapter cable to convert it from the 6 port to the 10 port motherboard header pin type connector with pins sticking out. Getting physical adapters is not a problem. The problem is it only has 1 power pin shooting out 12v, and I verified it with a multimeter.

Front panel diagram states the firewire pin needs 24v which you would usually just join the 2 12v pins from the firewire header on a motherboard. But I don't have firewire on my motherboard as I mentioned above. So would the front panel work with just 12v feeding into the 24v pin or will I have to tap another 12v from someplace else?

#2
BlackCH

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As per the IEEE 1394 specs you should have 30v-no-load coming out from the pin 1 (on the 6-pin external connector type):
http://pinouts.ru/Sl...94_pinout.shtml

On the 10-pin internal connector you should split this signal in two (going to pins 7 and 8).

I guess you would have to try connecting a firewire device to see if it works at 12v...

#3
Flybye

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See I'm totally confused because of what this article says:
http://support.apple.com/kb/HT2952

"Output voltage range: 12 V to 30 V (varies by product)"

I think I remember reading on another site that the firewire port goes into a power saving mode when not in use, and that it can scale up to 30v.

I just don't want to have to put it all together and then not have the entire front panel work. :( I don't think this is the case, right? USB has its own power, LED gets its own power from LED on +, etc.

#4
BlackCH

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The front panel circuit gets the GND signal through the firewire internal connector (pin 3/4). As long as you provide that signal the other connections will work.

Anyway, I think if you split the firewire voltage in two it will work just fine.

#5
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I'm going to go ahead and try it. :)

By the way, I wish I would have seen your thread on the cables you sell. I should have just purchased one of those from the beginning. I've already spent half of that in other cables I have already purchased. :wallbash:





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