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iMac G5 Power Supply Question


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#1
Dirk Monson

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I recently acquired an iMac G5 logicboard (1.6Ghz) that had the leaky capacitor problem. Anyhow, I fixed this problem (installed new capacitors) and now the logic board is good as new. So here's my question.

I want to use this logic board as a standalone unit without the iMac shell. I've seen this done before, however in that example he used the actual iMac G5 power supply. I don't really want to have to spend another $100 on just a power supply.

What other options are there for power supplies for the iMac G5 logic board? Is it possible(has anyone done this) to rig up a standard ATX power supply (I know the pinout is different)? Would it be possible to use a power supply from a Power Mac G5? Any suggestions on this would be greatly appreciated!

#2
cnoyes72

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I recently acquired an iMac G5 logicboard (1.6Ghz) that had the leaky capacitor problem. Anyhow, I fixed this problem (installed new capacitors) and now the logic board is good as new. So here's my question.

I want to use this logic board as a standalone unit without the iMac shell. I've seen this done before, however in that example he used the actual iMac G5 power supply. I don't really want to have to spend another $100 on just a power supply.

What other options are there for power supplies for the iMac G5 logic board? Is it possible(has anyone done this) to rig up a standard ATX power supply (I know the pinout is different)? Would it be possible to use a power supply from a Power Mac G5? Any suggestions on this would be greatly appreciated!




Look at www.xlr8yourmac.com. There is a pinout of the iMac G5 17" rev a power supply there. The easiest way to do the conversion would be using an ATX extension cable (24 pin) and hacking off the last row of pins. Then you would just need to rearrange the wiring between the PS and the Mac (using the extension cable keeps you from hacking apart your ATX PS in case you ever want to use it some where else).

HTH,

-Chris Noyes

#3
Dirk Monson

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Chris,

That helps a ton. Hopefully by the end of the week I'll have a spare moment to make the cable.

I'm assuming the +24V is used to power the LCD inverter and probably isn't really necessary since I'll be using an external display. What are your thoughts on that?

#4
cnoyes72

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Chris,

That helps a ton. Hopefully by the end of the week I'll have a spare moment to make the cable.

I'm assuming the +24V is used to power the LCD inverter and probably isn't really necessary since I'll be using an external display. What are your thoughts on that?


Yeah, the 24VDC line looks to be for the display (backlighting). I have a 1.8GHz board from a 17" imacG5 I'd like to use with an ATX PS I have sitting around. The only "issue" I see is trying to get the internal optical drive working; it uses a laptop style connector for the optical drive (same connector that is in other laptops and on the back of the optical drive unit itself). Too bad they didn't use SATA for that connection.... I'm looking to mount this in a Cherry wood case.

-Chris

#5
learning_bird

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Did you had any luck with using an ATX PSU with the iMac G5 board?

#6
psychozz

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I am also interested in this! What I can see, the only thing to do is to rewire the three +12V pins and somehow fix 24V to the extra 22nd pin at the end of the connector, am I right? But how do you get 24V out of a 12V ATX power supply?
Would it work to use a second power supply that outputs 24V just to that pin and connect the ground to the extra ground connector at the end?

The iMac's power supply pinout: http://www.xlr8yourm...pply_pinout.gif

#7
tayklor

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I am going to do the same thing as I can get iMac G5s with bad power supplies for $40 each.

#8
hoodmulti

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I just tried to use a normal PC ATX power supplied, swapped in two +12V cable at the pin, but left the +24V pin unplugged, and it worked.
My dead iMac G5 resurrected.

It would be great if anyone knows what the +24V is for?
Cheers.

#9
ESP

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HI

using an external Monitor?...

please let me know , i've the same problem.

bye, thanks in advance.

#10
tuffhamster

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WOW thanks everyone. I was about to sell of my dead imac as faulty on ebay and thought I would give this a go. Had to just change over 2 x 12v wires and it works perfectly ;)

#11
jphuard

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Hey I was wondering if anyone would mind posting pictures? It'd be really helpful for anyone who has yet to do it and would rather not worry about screwing up ;-) (like me)

Thanks

#12
phutterman

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I've recently considered the same thing, as I acquired an iMac board as well. However, at this point, I am using the iMac power supply, as I may also connect its LCD panel, which requires the original power supply for the higher voltage. I do have an ATX extension cable which for the moment I am using just to extend the iMac power supply's cable (as it is just straight through) but also might use it to adapt an ATX power supply to the iMac board, and then use the iMac power supply just to power the display, though that would be another whole big project.

I'm putting the iMac board into a PowerMac G5 case that had a coolant leak, so I got it for free, and just had to clean the corrosion out myself. Once it's done I may post some pictures.

Anyway, I just wanted to remark that if you're using an ATX power supply, you might consider getting a laptop optical drive to IDE adapter (ie http://www.dealextre...s.dx/sku.10573). It lets you connect a regular IDE drive to the laptop optical drive connector on the iMac motherboard. However, it is only for data, not power, so you would also need to connect the drive to a regular 4-pin Molex from the power supply as well. At the moment, I can't do this, as I'm using the iMac power supply, which only has the 20-pin connector and no 4-pin ones, but this would be one reason I'd switch to an ATX.

#13
BigDyno

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I know this is an older post, but i figure i found this thread through Google, so I imagine someone else will. I was given a "broken" iMac g5 20-inch computer. I was told that the power supply had to be replaced. I found a powersupply for sale for $10 (rather then the $200 the tech quoted me) But the psu was pulled from a 17 inch, (and has different part number.) Does anyone think this makes a difference? Will it work in my larger 20 inch? After reading this thread and seeing a regular atx psu was used, it makes me think that there would be nothing different between the two. Any reply's would be great, Thanks!

#14
Reveeen

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BigDyno:

The tools you need are posted in this thread............ compare the pin outs at http://www.xlr8yourmac.com/ keeping in mind that if the same, the wattage is likely to be smaller.

#15
Eligos

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I know this is an old thread but since I am about to swap out my dead iMac 20" PSU for an PC ATX, I need a few precisions.
Some of you here used a PC ATX successfully. Could you please tell me if your main LCD works with this setup or do you need an external monitor since the +24v isn't being used?

Many thanks for your reply,

FS

#16
GreggyB

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I am going to do the same thing as I can get iMac G5s with bad power supplies for $40 each.


Hey! I know that this post was some time ago (about 2 years), but I'm brand new here and found this thread-looking for info on replacing a power supply on the iMac G5. So, I'm wondering if this statement you gave is still true? Where can one such as myself get a G5 for $40?
Thanks so much.

#17
Nyleveia

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I felt i would add my experiences, since this would also be my first post also.
I have a 20" iMac G5, 1.8ghz that wasn't booting at all, just led 1 illuminated, mac store said it was the logic board, i thought otherwise.

I connected an atx psu switching the above mentioned pins for 12v+ and hey presto, it booted with chime and continued, only problem being that there was no display, i recall someone posting that the 24v is for firewire - this may well be the case but i can confirm that for the 20" g5, this is needed for backlight to function, i connected the old psu and grounded pin 14 (to tell it to turn itself on), with the 24v and ground connected to the corrosponding connectors on the g5, the result was the machine booted just fine, with display functioning perfectly.

Now its just a case of me getting a working psu for it, or having a go at replacing all of the caps in it and hoping one of them is dead (none of them are obviously dead, no leakage or expanding).

#18
Nyleveia

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I've encountered a really odd situation, when connecting the original psu for 24v+ source (connecting pins 14 and 15 to keep it on), the psu was emitting a low squeel, however i continued and reinstalled osx, after doing so and installing various updates i came to remove the atx psu, and just out of curiosity, reconnected the original psu, which had stopped squeeling about half way through a reinstall.

And low and behold, its now back to working just fine, weird!

#19
jppetertil

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Thanks so much for all this info. I put a new ATX PSU into my iMac G5 17" power pc and everything seems to be working great with only 12V hooked up to the 24V pin.

I also replaced some logic board capacitors. Apple had estimated $600-700 for these repairs and I did it all for about $65. Awesome!

#20
kiwiron

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Hi folks, this is another question really, as I'm new so can't post a new topic yet.
I've a G5 20" isight with a blown 661-3780 power supply. The DC out for these is only 5 pins and the supply itself states 12.1 volts and 15.4 amps. Can anybody please indicate the voltages on the 5 pinouts. The wires are 2 grey, 2 black, and 1 brown. The grey and black wires are joined on the power supply circuit board, so its really only 3 pinouts. I want to test the machine before splashing out on an expensive replacement, but haven't been able to find the pinout voltages anywhere. Getting desperate!





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