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PowerMac G3 Power supply difference

froggytreafrogg

froggytreafrogg

macrumors regular
Original poster
Jun 1, 2008
193
0
Louisiana
Hi, I'm building my own PowerMac G3 as part of a project. I'm curious to know what makes a PowerMac G3 power supply special. I have lots of PC Pwrsply's and it would be great if I could fit one of them into the PowerMac G3 case that I have. It makes things easier and cheaper since I won't have to buy another power supply. Any response-thanks! :apple:
 
The mainboard connectors are not standard like they are on a PC. You would be better off picking one up off ebay...
 
I assume you mean a Beige G3.. and they connectors are standard.

However, assuming you are talking about a Beige G3, you can use a standard ATX PSU; there's a switch on the motherboard right behind the PCI slots that says "MAC Supply" and "PS/2 Supply". Actually it's not a switch, but jumper.... which you set depending on which supply you're using. Obviously the MAC is the Mac PSU that came with the Desktop model, and the PS/2 is for a standard ATX PSU (which shipped in the minitowers).

http://www.heise.de/ct/english/97/13/208/gossamer.jpg

You can kinda see it in that diagram. If you need another picture I can upload one.. I've got a spare Beige G3 MoBo lying around.

If you mean the B&W G3, from what I can tell from mine, it's a standard ATX PSU.
 
Firefly2002 said:
I assume you mean a Beige G3.. and they connectors are standard.

However, assuming you are talking about a Beige G3, you can use a standard ATX PSU; there's a switch on the motherboard right behind the PCI slots that says "MAC Supply" and "PS/2 Supply". Actually it's not a switch, but jumper.... which you set depending on which supply you're using. Obviously the MAC is the Mac PSU that came with the Desktop model, and the PS/2 is for a standard ATX PSU (which shipped in the minitowers).

http://www.heise.de/ct/english/97/13/208/gossamer.jpg

You can kinda see it in that diagram. If you need another picture I can upload one.. I've got a spare Beige G3 MoBo lying around.

If you mean the B&W G3, from what I can tell from mine, it's a standard ATX PSU.
Click to expand...



No, sorry for that misunderstanding. My fault. It's a Yosemite (blue and white) however i will check into that jumper. thanks.
 
matt321 said:
@firefly:

You're right! I apologize for the confusion.

If you look at these two diagrams, you will see they are the same:

1. Regular 20pin ATX Power Supply


2. G3 Power Supply Pins


I was thinking of the G4 power connector, which is 22-pin and not standard.
Click to expand...



Thanks for the response. i'm just a bit confused. is there any jumper setting that i need to change. (btw it is a blue and white pm G3) I have some pwr splys that have that type of connector. i just need to be sure if i can or can't put that on my g3 MoBo. The power supply that i'm looking at is an ATX 2.03 (P4) and the color coding/voltages are the same as the diagram that "Matt321" provided. However, the male connectors are not the same. Thanks again.
 
froggytreafrogg said:
Thanks for the response. i'm just a bit confused. is there any jumper setting that i need to change. (btw it is a blue and white pm G3) I have some pwr splys that have that type of connector. i just need to be sure if i can or can't put that on my g3 MoBo. The power supply that i'm looking at is an ATX 2.03 (P4) and the color coding/voltages are the same as the diagram that "Matt321" provided. However, the male connectors are not the same. Thanks again.
Click to expand...

No. As far as I know, the B&W uses a standard PC ATX PSU, so any will do.

There's no jumper on the B&W MoBo, only the Beige.
 
Firefly2002 said:
No. As far as I know, the B&W uses a standard PC ATX PSU, so any will do.

There's no jumper on the B&W MoBo, only the Beige.
Click to expand...

well, i found out that the connectors on the mobo and pwrsply are the same and some diagrams on the internet showed that they had the same voltage, so i dont see why it won't work. thanks for the response
 
froggytreafrogg said:
well, i found out that the connectors on the mobo and pwrsply are the same and some diagrams on the internet showed that they had the same voltage, so i dont see why it won't work. thanks for the response
Click to expand...
I don't think you can just simply plug in an ATX supply without some rewiring. If you compare each lead there are some differences, pin 8 (+3.3v Mac, p.g. signal ATX) and pin 18 (GND Mac, -5V or blank ATX). This guide from XLR8yourmac.com lists what leads you need to modify to make an ATX powersupply properly work on your computer.

G4 (AGP/Sawtooth) to ATX case Conversion

Though the guide is for a Sawtooth G4 if you notice the Sawtooth Pin out matches the G3 B&W pin out linked by Froggytreafrogg. It is not until the Gigabit G4 that you have the 22pin connector on the G4 and the MDD/FW 800 use a 24pin connector. Incidentally there are hacks for using an ATX supply on these G4's as well by also using a secondary supply for the +28V lead.

All G4 Pin-Outs sometimes this page does not work
 
velocityg4 said:
I don't think you can just simply plug in an ATX supply without some rewiring. If you compare each lead there are some differences, pin 8 (+3.3v Mac, p.g. signal ATX) and pin 18 (GND Mac, -5V or blank ATX). This guide from XLR8yourmac.com lists what leads you need to modify to make an ATX powersupply properly work on your computer.

G4 (AGP/Sawtooth) to ATX case Conversion

Though the guide is for a Sawtooth G4 if you notice the Sawtooth Pin out matches the G3 B&W pin out linked by Froggytreafrogg. It is not until the Gigabit G4 that you have the 22pin connector on the G4 and the MDD/FW 800 use a 24pin connector. Incidentally there are hacks for using an ATX supply on these G4's as well by also using a secondary supply for the +28V lead.

All G4 Pin-Outs sometimes this page does not work
Click to expand...


wow thanks for letting me know. it's a good thing i didn't plug my mobo up to that without the mods.
 
I have a standard ATX Power Supply pluged in to my Power Mac G3 (B&W) it works fine part from a very small thing that when power is fist added to the power supply the computer will turn on with out pressing the power button and when there is a power cut and the power comes back on same thing other than that it works fine i think somthink to do with some power macs used +5V for power on, rather than the ground like the ATX uses.
 
firmware bug?

sorry for bumping this year old thread. I found it on google. here's what I've got:

summary of this long rambling:

my troubleshooting hints that there may be a firmware bug in the g3 beige desktop (the ones that have the PS2/Mac jumper on the motherboard) that prevents OS9 from working when it's running off of a PS2 power supply.

I've got two Mac G3 Beige desktops. One is jumpered to take a Mac power supply. The other is jumpered to take a PS2 power supply. Both were working with their respective power supplies. I have no idea where the G3 with the ps2 supply got it's power supply from originally, except that it wasn't the correct shape, so it must have been added in by me at some point in an attempt to increase the wattage, as I had a crazy number of drives stuffed into the thing.

So I pulled the ps2 power supply out of the beige and stuck it in a blue and white in an attempt to increase the wattage of the B/W as I moved all my drives over the the B/W. The B/W works fine.

I then proceeded to stuff a mac power supply into the desktop G3 without correctly setting the jumper, and it made weird clicking noises and the keyboard lights flashed and it wouldn't boot AT ALL. Of note is that this mac power supply is the correct shape for the desktop beige G3 - all elongated as it is.

So I eventually find the jumper. So I switch the jumper over to "Mac" from "PS2" and the computer boots.. sort of... The beige g3 with the PS2 supply now books into OSX...10.2 and it boots into 8.6.. but it won't boot into 9.2. On the "welcome to macintosh screen" one or two extensions load, then it pauses, then the relatively low-level "you're f----ed" box pops up on the screen... whereas normally there some be some catastrophic error in the box, it is just empty, and the system is hung.

So I'm like.. okay.. maybe I've got a corrupted OS on the hard drive, so I tried booting to the 9.2 system install CD, but same deal... so I replace the CDrom drive, I pull all the extra memory, cache, video memory, sound card, ide cables, scsi cables... same deal... I swap processors between the two G3 motherboards (swapping the processor setting jumper block along with the processor) and... same deal....

(other troubleshooting as appropriate to make sure I'm narrowing down the problem correctly: zapping PRAM along the way, unplugging all hard drives to make sure I'm booting off the CDROM and only the CDROM, hitting that "reset" button on the motherboard, checking the voltage on the PRAM battery to make sure it's 3.5 volts, and all that jazz...)

great, I think.. I musta fried the motherboard with my stupid power supply trick of plugging a PS2 supply into the board when it was jumpered for a Mac supply...

so I swap motherboards, so now I've got a known good motherboard in there, and I jumper it to PS2, and amazingly... same deal.. still freezes in the same spot, only booting to 9.2...

so... conclusion... there is either something wrong with my power supply, (which I am relatively sure originated in the B/W) or, if the power supply is conforming to all relevant specs, then there is something wrong with the behavior (e.g. firmware bug) of the GE beige desktop when it's jumpered for a ps2 supply... of course... it was working in 9.2 before... so... I mean... I'm fairly sure if I popped the original PS2 style supply back in it, (the one that I threw in the B/W) that it would work in either Beige G3.

The fact that I can boot, with the ps2 power supply in the G3 beige desktop, into a couple of different versions of the OS, but one version of the OS won't boot... that is very suspect... and very interesting. That's the point of this post... I can't say for 100% sure where any of these power supplies came from because I got all these computers used and I don't remember what if anything I've done to them over the years as far as swapping parts around.

only thing I didn't swap out was the keyboard and mouse... and hmmm... I have another ps2 power supply from a PC server... maybe I will plug that sucker in... the cord is long enough to reach without pulling the supply out of the case...

anyway... it's a little late to be learning new things about systems this old :)

PS--
so uh.. yeah I just looked at the power supply that was working in the G3 beige desktop jumpered for a PS2 and is now working fine in the Blue and White G3... and uh... it's one that I modified... .. okay... peeling off the tape from the cables, what do I find... okay.. I've simply cut the white wire and the one that's across from it on the connector... looks kinda dark in color.. I can't tell what color it is because I'm partly colorblind. The white wire connects to a pin that is third from the top right if the unwired end (interface end) of the connector is facing you with the clip on the top. and that worked with the beige G3 desktop motherboard jumpered as PS2... And the B/W doesn't seem to mind it either...

okay.. there's some random info for ya... I'll try cutting those wires on my other ps2 supply and see if I can boot into OS9 after that... I'll post a reply when I have a chance to try it... right now I'm going to bed...
 
Just to confirm, the xlr8 schematic link above works. I used it to change a standard ATX psu into a mac PSU for my G4 Sawtooth. Splice a couple wires and you're done; if you want cheap and easy, go to radio shack and pick up some plastic splicing units; they're little blue plastic "snap-on" wire splicers with a thin metal plate through the middle. You just cut the wire to splice to and line it up with the wire to splice into, close the plastic snap, and press down the plate with a pair of pliers. Takes seconds and saves you from worrying that solder or electrical tape could erode over time...
 
Hello everybody

I have a Power Supply of a G3/266 Tower, the motherboard is dead but the power supply is functioned ok and i want use it in a project.

I was reading the topic and I found that the pin 14 (green wire) is the power on, but I do not know with wich pin I have that do the bridge to turn the power supply

If somebody want give me a hand leave the link where show that is each pin

http://www.allpinouts.org/index.php/Power_Mac_G3_Mainboard_Power_Supply

Thanks in advanced
 
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