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g5 power button fail using alohacab's cable harness


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I bought one of those g5 front panel to atx cable harnesses from alohacab awhile back but am still unable to get the power button and led to work. The usb and firewire ports both work though. He told me when I first brought it up to him that there was probably a problem with the ground path, but I can't figure it out.

 

He has the ground path set up throught the firewire connection. I've got this connected to a firewire card that I bought from newegg that has the 10-1 pin connector that he provides. I've continuity tested all the leads on the cable harness and everything seems to check. Also too, both the firewire and usb connections work properly: I've connected two different drives through each port with successfully seeing them in windows explorer.

 

I just can't get the power button to work. I've tried connecting a ground wire from the front panel port power switch ground pin on the mobo directly to the chassis with no luck. I finally bought a new power pcb and replaced the old pcb: no luck. However, this time when I press the power button, the led lights up. But only while the button is pressed.

 

I can also confirm that the mobo front panel power switch pins work as I can power up the computer using a flathead screwdriver to short the pins.

 

For any of you who have bought this cable harness, do you have any suggestions as to how I might be able to track this issue down?

 

Since the grounding is happening through the firewire connector, could it be that the firewire card isn't live yet? Would I need to jumper the ground through another route altogether? If so, thoughts as to how to do this?

 

Thanks for any help you all can offer.

 

If worse comes to worse, I'll just rig up a separate switch button, but i really don't want to resort to that if I can avoid it.

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If the led lights up means that somehow the GND signal is coming ok. I guess you have the power/led connectors changed around or fliped. Check that.

 

If that doesnt work, you should get a multimeter to be able to detect whats causing the problem: the cable or the front panel board itself.

With a multimeter you can check for continuity in any section of the circuit.

 

If you have access to one of those (you can get a basic one for about 10$), let me know and I can explain you what/how to check.

 

Cheers

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Yeah, i have one and i've pulled apart the front panel enough to more or less identify what to check where. So please do tell me how to proceed.

 

Thanks for helping me out with this.

 

I was just getting ready to buy a new front panel, but don't want to do that if the ground problem still persists in the firewire card or whatever.

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ok, first unplug the cable adapter and check if the ground wire on the firewire connector is wired where it supposed to be:

 

follow this diagram:

http://www.insanelymac.com/forum/topic/4525-discussion-fit-a-pc-in-a-g5-powermac-enclosure/?p=614504

 

Check for continuity between pin 5 on the 18 pin connector to pin 3/4 on the firewire connector. Thats the ground signal.

 

Actually you can download the full diagrams from here:

http://www.insanelymac.com/forum/topic/109381-powermac-g5-diagrams/?p=775143

 

and check every wire on the cable just to make sure all is ok.

 

If you never used a multimeter before, you need to put it in continuity mode (usually marked by a  like-a-wifi icon). Then put one of the needles on the 18 pin connector and the other on the motherboard connector side. Just follow the diagram you downloaded before to know what pin goes where. If the connection is good the multimeter should "beep".

 

Do that and let me know how it went.

 

Cheers

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So, it looks like he's got the Firewire (FW) pin 3 (FW GND according to the diagram) connected to Front Panel (FP) pin 2 (FW GND) instead of pin 5 (FW Shield GND) as you suggest. His jumper from 3 to 4 does work. It appears that all the other connections are correct as well.

 

Indeed, his wiring is in fact according to the diagram you linked. FP pin 2 to FW pin 3 (jumpered to FW pin 4) and FP pin 5 to FW pin 10.

 

However, you're suggesting that FP pin 5 (not FP pin 2) be connected to FW pin 3? Is that correct?

 

I have taken into account that the diagram is showing the FW card pinout and that my cable harness connector would be the reverse of that. Using that logic all connections have continuity.

 

Thanks

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My mistake, FP 2 should be connected to FW 3/4 (as you have it now).

 

Look in to fix the bridge from FW pin 3 and 4, but I dont think that is the problem.

 

So, if all the connections are ok as you say, you are probably looking to a dead front panel board. Probably some cracked solder point.

 

Can you confirm USB/Firewire/audio works (once the machine is on, of course)?

 

 

Next thing is to do the same check you did with the cable but this time plug it onto the board. It will be better if you extract the board from the case so you can work better. I would start testing the GND signal (which seems to be the problem)...

 

I will post a picture later with more details

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This is what you get once you extract the FP board:

 

post-51637-0-84859600-1371816946_thumb.jpg post-51637-0-49982100-1371817438_thumb.jpg

 

I marked the pin 1 with a red circle (pin two is the next to the side, and so on). You should check the continuity within the board itself. Use the diagram you downloaded before to match the pins in the pictrure above.

 

Test the continuity from the pins on the upper face of the board to each pin on the connectors. You can get the pinout for usb and firewire on the internet.

 

If the power button/led where the problem start with those (and the FW gnd signal); test from the pins on the 18 pin connector to the little connector where the power button plugs in.

 

Cheers

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Man, I have no idea what happened but it works now. It might have been the button/led pcb that i replaced and then just had the power and led lines crossed. I can't think of anything else.

 

Anyway, thank you for taking the time to help me out on this. This whole thing was really aggravating me.

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Thank you BlackCH for helping with an issue on a 'competators' product, no less! And thank you jonnysporto for marking the question answered.  

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Actually, it turns out the problem still isn't resolved, but for the purposes of this thread it is. It's the board. After I had reinstalled all of my equipment (I was also having problems with my power supply and had to replace it) the stupid power button/led stopped working again. I pulled out the SSD/HDD cage and started wiggling the board and pressing the connector into it harder and it would flick on and off. There's a bad connection in there somewhere. So, I'm just going to get another one.

 

So for anyone who's made it this far, please note that Alohacab's cable is perfectly good. At this point I believe my problem is a bad front panel board which I will replace.

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In my opinion is the FP board. Im sure theres a cracked solder point there (probably on the 18 pin connector). Sometimes does making good contact, sometimes doesnt.

 

You could just redo the solder on the connector (if you have a solder iron) and see what happens.

 

Im telling this because had happened to me a couple of times...

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Final update on this post: it was in fact the front panel. I work at place that over the years has accumulated a lot of powerpc G5s, which are just now getting all scrapped out. So I was able to pluck another front panel off another dead computer and sure enough success!!!!

 

{censored} hell, what a stupid problem to have.

 

Power button is fully functional, front panel is fully functional. Now onto finally installing my hackintosh.

 

Happy hackinstoshing people!

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