Power Mac G5 Power Supply using ATX PSU Options

[juragan]

Does anyone successfully replace Power Mac G5 PSU with ATX PSU ? One of my G5 PSU just blew and tried to replace but the cost of new PSU is quite high ($ 150).

Tried to google on G5 PSU pinout but no luck

Appreciate if someone can share the knowledge.

[teknojunkie]

not possible as of right now we tried the other way using a G5 powersupply on a pc motherboard, would be great if you could

[juragan]

I've done some research through uncle Google and found some interest white paper. This is the pinout for G5 power supply. But, i havent seen the exact from the physical PSU itself and check all the voltage and pinout using my voltage meter. Maybe someone can check it out.




continue...

[juragan]

Here's what i got so far from the ATX 2.0 pinout





what we have missing so far from G5 PSU is the +25V (i mark with red box at P2 pinout) which i dont know for sure what kind of device or component is required that kind of voltage. Another thing is the pin# 3 is i believe for fan tachometer (sensor).

The rest is mostly there in the ATX 2.0 PSU.

I know some of you in here have much more experience and knowledge in the G5 hardware that can share with us.

Anyone ?

[eot8857]

Here's what i got so far from the ATX 2.0 pinout





what we have missing so far from G5 PSU is the +25V (i mark with red box at P2 pinout) which i dont know for sure what kind of device or component is required that kind of voltage. Another thing is the pin# 3 is i believe for fan tachometer (sensor).

The rest is mostly there in the ATX 2.0 PSU.

I know some of you in here have much more experience and knowledge in the G5 hardware that can share with us.

Anyone ?

Hey juragan - I'm afraid I won't be too much help on this, as the differences between x86 and g5 processors will undoubtedly carry over into their power requirements. The voltages are a good place to start, but you are probably going to need to know what the amperage requirements are for the voltages. If you draw too much amperage from a power supply (provided it doesn't shut down), voltage drops. If voltage drops too much, hardware crashes or refuses to start.

From my best "guesstimate", I would venture to say that the p1, p2, and p3 connectors are for motherboard, drive cages, and CPU (respectively).

I've "reworked" power connectors in x86 servers, but usually the power requirements match up fine. The good news is that if you find some ATX power supply of the Gods that can supply an enormous amount of amperage, that's fine. Amperage is "drawn" by a device, so high amperage is not bad. Think of your household breaker box. Most rooms carry 15-40 amps to their circuits, and a 120 watt bulb pulls 1 amp (1 amp x 120 volts = 120 watts). So, although you don't want to go over on voltage, more amps is not going to hurt anything.

The only insight I can give you for certain is on the 25v lead. Depending on your g5 configuration, you may or may not have an apple display with the proprietary ADC plug (looks like a large DVI). The ADC is a single connector that provides DVI video, USB, and up to 25V to power the monitor (it doesn't have its own power plug). Your 25v lead is supplying the power for that ADC connector through the motherboard's AGP. Actually, it's a 6-pin socket between the AGP and the case (it looks like an extension of the AGP). If you don't have that socket, you probably don't need to worry about the 25v lead.

If you manage to figure out something that works, let us know. Better yet, market an adapter harness and sell it. I'd be willing to pay upwards of $150, since my dual g5 supply costs $290... refurbished.

Good luck -

[juragan]

eot8857, appreciate your input and the knowledge share. I have look up on my G5 AGP card and it has an extension on the board to the AGP card. Meaning, i can skip the 25V as long i'm not using the ADC plug (bigger DVI) ?  

As far as I know, the 1.6 PPC G5 required 450 W PSU and I dont know about the amperage supply. (edit: mine is single processor)

But I will keep continuing to seek more information to see if this project can be successfully implemented. 

/prays   

[cwd14]

does anyone have any updates for this thread? I have tried to search for information on this and have failed miserably. I have also tried to get an ATX PSU to work in a powerMac G5 without success by splicing the wires and matching the voltages.

So far if I force the power supply to turn on by connecting the green power on wire to a ground it moves the fans just a little bit and then stops. Pushing the power button does nothing. Thanks for any help you can provide.

edit 9:50 AM PST - I just got the red light on the motherboard to turn on when I force the power supply to turn on. I do not know if this indicates that the motherboard is bad or if it just means that some part of the board does not have power since the power button still does not work.

[cheebster]

Hi ! First post here. I got a g5 (my dad's..) i need to fix. So far, i got it to power on, the white led is there, fans spin up.. after about 60 seconds, it shuts down. Right now i'm feeding 12VDC to the white wire for ADC.

I dont have any dvi to adc converter, so i'm using the second DVI ouput of the video card. I don't have any display, but i can hear the 'chime' or whatever that startup sound is called on the internal speaker when i power the G5 up.

Does that sound mean the G5 is powered on, that means POST ok ? I'm wondering if i would get a display with a ADC to DVI converter on the other port. I got no clue why the machine shuts down, if anyone has a hint. One thing i think of is, that FANtach signal (PIN3, white/yellow) which checks the fan in the psu i think. I might be able to bypass that one, but i don't know how. Maybe hooking to some other internal fan's tach signal ?

Any kind of help would be great !

cheebster.

[ntsmkfob]

If you search for powermac_g5.pdf in google, you should be able to find a copy of the manual, which contains troubleshooting guide etc.