my powermac g5 problem

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Joined: Jul 13 2007
Posts: 179

recently, my powermac g5 has a problem. when I press button. the front panel led no light. but power still turn. I check information in the internet. maybe it is power supply problem. G5 series released in 2004-2005. if I use power pinout. can I solve this problem??? I heard this series power component has a little problem. can I replace with atx power? and now I bought a motherboard and cpu. original motherboard can't force shutdown if you press button. so I consider if want to buy power supply. so ask everyone. thanks.

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Joined: Jan 19 2011
Posts: 52
Re: my powermac g5 problem

I'm confused.

Is the computer powering up and operating ok and just the LED doesn't light or does nothing happen?
It's rare, but LEDs do blow out sometimes.
I can't suggest any new supplies as I usually repair things at the component level, but I do wish you good luck.

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Joined: Jul 13 2007
Posts: 179
Re: my powermac g5 problem

this led can't light on. but fan will turn. I use Meter measurements are fine. but motherboard can't force shutdown and see some capacitors are a little exploding. I feel it should be motherboard's problem. and now I consider if buy power supply to pinout it.

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Joined: Jan 19 2011
Posts: 52
Re: my powermac g5 problem

This sounds like another casualty from bad caps.

I've had to recap a G5 (and others) before and it's not terribly fun.
The solder they used appears to melt at a very high temperature.
Neither one of my Hakko desoldering stations could desolder them alone.
I had to simultaneously heat the joints with an additional soldering iron.

For more info on these type of capacitor problems, see here:

http://en.wikipedia.org/wiki/Capacitor_plague

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Joined: Jul 13 2007
Posts: 179
Re: my powermac g5 problem

that's right. my capacitors it is just like the below link picture. I can certain my motherboard has capacitor problem. when it can worked before. I usually heard the fan turn so quickly and noise sound. I metered volt with power supply. it is normal to appearance every line volt. and now I find a problem. I bought this motherboard is powermac g5 1.6g for daughter board. my original motherboard is 1.8g single. cpu on board. 1.6g ,can it use ddr400 ram. I wonder if I use wrong ram. g5 motherboard if you don't plug any ram. it is no chime or any sound??

please respond me. thx

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Joined: Jul 13 2007
Posts: 179
Re: my powermac g5 problem

I just assembled my g5 motherboard into case. turn on the power. but strange thing occur, front panel led flash many times. I checked website. it mention ram problem. I use ddr 3200 ram. flash light and never stop. what's problem that I have never know. does anyone know??? I press power button,I can force shut down. but motherboard reset button. it becomes shut down. does any one know??

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Joined: Jan 19 2011
Posts: 52
Re: my powermac g5 problem

While voltages out of a power supply (+12, +5, etc) may appear fine and within range on a DC voltmeter, one is not checking AC content then.
The larger purpose of the capacitors is to filter out AC ripple and frequencies generated by the switching supply.
So reading a normally DC voltage purely as a DC voltage is one thing.
Putting an oscilloscope on those lines to see their AC content is another.
Doing this or properly using an AC meter might reveal some not-so-pure DC levels and this is where problems can multiply.
All of the subsequent parts seeing this power will deal with it in their own ways.
Some will degrade (capacitors and certain semiconductors), some will overheat and some will die completely.
Certain parts like tantalum caps or motor driver ICs may even explode when trying to dissipate excessive AC under load.

So please don't run your computer until these problems are solved.
I suggest a complete recapping of both the power supply and the motherboard.
I also suggest that only someone experienced and properly equipped attempt the jobs.
You may find ready to use power supplies or even motherboards on Ebay, but be wary that they may also have bad caps unless previously serviced or upgraded devices are being offered.

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Joined: Jul 13 2007
Posts: 179
Re: my powermac g5 problem

I guess everyone feel so strange and want to know what answer is. I tested it over and over again. I can certain it is motherboard problem. so I abandon it and sell case and all of components. thanks for everyone respond.