G4 MDD ATX PSU Conversion

[andysa1966]

I'm looking for a suitable ATX PSU to attempt a conversion for MDD G4, I think I've found one albeit on the expensive side, technology has progressed and this one easily fits into the originals location, any thoughts on this psu?

FSP400-50FDB 400W Flex ATX 1U Gold power supply – Overtek

 

[eyoungren]

I'm looking for a suitable ATX PSU to attempt a conversion for MDD G4, I think I've found one albeit on the expensive side, technology has progressed and this one easily fits into the originals location, any thoughts on this psu?

FSP400-50FDB 400W Flex ATX 1U Gold power supply – Overtek

I usually point people to this site: http://atxg4.com/

I've never done it myself and I don't know if this will help you.

 

[padams35]

I tried (and failed). It turns out I am really bad at pulling pins to rewire connectors, and the extension cable I purchased thinking I could cut/splice failed because it was completely missing a wire/pin that is unused by ATX but expected by the MDD. Eventually I decided a Rasbery Pi would make a better hobby computer.

Other than that warning and a warm wish of luck I think a PSU that solves or simplifies the mounting problem is an excellent choice... just make sure you have a working plan for the ATX to MDD wiring before you buy said PSU.

 

[reddrag0n]

ATX G4 MDD PT1
ATX G4 MDD PT2
ATX G4 MDD PT3

 

[andysa1966]

Thank you for replies, I've read up about the pin diagrams, I've got the ADC connection covered using apple external dvi to adc adapter which has its own psu negating the missing internal 25v supply

 

[reddrag0n]

i did read sometime back that you could incorporate the +25v line into the power supply using a walwart (wall plug) and tie it into the mdd power line. never tried it myself, and the way i tried failed using a dc booster to go from 12v to 25v.

this was my original attempt years back PowerMac MDD PSU mod

 

[andysa1966]

this was my original attempt years back PowerMac MDD PSU mod

Thank you for sharing, if the input socket doesnt line up with the g4 case from outside then im also thinking about transferring the innards of the psu into the old psu case as an option.

It might seem like more trouble than its worth, but these old macs are so iconic its a shame to let them die

 

[padams35]

Thank you for replies, I've read up about the pin diagrams, I've got the ADC connection covered using apple external dvi to adc adapter which has its own psu negating the missing internal 25v supply

No, I mean pin 22? (the one opposite from POK)? is missing from some? most? ATX 2.x cables.

Its not a problem if you can pull pins and move the missing hole to the +25V spot, but it was a show stopper for my cut/splice plan.

 

[andysa1966]

No, I mean pin 22? (the one opposite from POK)? is missing from some? most? ATX 2.x cables.

Its not a problem if you can pull pins and move the missing hole to the +25V spot, but it was a show stopper for my cut/splice plan.

I'm not sure which pin 22 for the ATX to refer to, can you confirm on the attached diagram

 

[padams35]

This was several years ago so my memory is a bit fuzzy but I want to say both ATX extension cable I bought to modify were missing Pin 18 [on the ATX] / Pin 22 [on the MDD] diagrams.

 

[andysa1966]

I see what you mean, G4 doesn't require -5v which as you note was dropped on later ATX psu, pin 22 is +12v and should be able to create loop cable from either pin 10, 21 or 24.

 

[andysa1966]

Finally getting around to doing the PSU conversion, I ordered a 400W PSU, didn't have stock so they send a FSP500-50FDB part as a form, fit and function replacement.

Just looking over the wiring connections to adapt to the MMD, the 24 pin connector is short of two 12v (yellow) and one ground wire (black), there are plenty of auxiliary connectors on the PSU to tap into thou, my only consideration is the 3.3v (separate orange and brown wire) sensor connection at position 13, I'm inclined to connect to MDD position 6, but i don't really know what 6 is connecting to, just wondering if there would be a preference between 6, 17, 18 or 19?

Update, as it turns out position 6 on the mac connector also has aditional sense wire (thinner orange wire), I wired this wire direct to the brown wire that is connected to position 13 on the FSP connector. I inserted a connector into the FSP loom disconnecting it from position 13.

https://www.fsp-group.com/download/pro/FSP500-50FDB_ME2D.pdf

 

[andysa1966]

Ive done the ATX conversion, mac powers on and starts up, no video out thou from radeon 9000pro or 9700pro cards which have ADC outputs, even thou only connected to the DVI output of said cards. I know that the ATX doesn't have the 24v output, but I did realize the DVI wont work without the 24v on these cards, is there a work around?

I tried a radeon 9600 but it only output 256 colours, could be the card, cant remember how i came by it, only card working at the moment is a radon 8500ME.

Any ideas?

 

[andysa1966]

I think i have a solution, use a step converter (XL6009) to get from 12v to 25v to get the graphic card to switch on and use the DVI port, not to use ADC as the converter is only rated 1A or 24W at this range.

Test comparison sample reference :-
Input 3V Output 12V 0.4A 4.8W
Input 5V Output 12V 0.8A 9.6W
Input 7.4V Output 12V 1.5A 18W
Input 12V Output 15V 2A 30W
Input 12V Output 16V 2A 32W
Input 12V Output 18V 1.6A 28.8W
Input 12V Output 19V 1.5A 28.5W
Input 12V Output 24V 1 A 24W

​

 

[andysa1966]

Success, 2GBP XL6009 12v adjusted to 25v from ebay did the trick, radeon 9700 now working DVI out

I bought spares of everything apart from the psu in the eventuallity the apple 360w psu in my other G4 gives up ghost

 

[DiTBho]

is there a kit I can buy in Europe?
or do I need to wire-up an adapter?
my MDD needs a new PSU.

 

[reddrag0n]

Finally getting around to doing the PSU conversion, I ordered a 400W PSU, didn't have stock so they send a FSP500-50FDB part as a form, fit and function replacement.

Just looking over the wiring connections to adapt to the MMD, the 24 pin connector is short of two 12v (yellow) and one ground wire (black), there are plenty of auxiliary connectors on the PSU to tap into thou, my only consideration is the 3.3v (separate orange and brown wire) sensor connection at position 13, I'm inclined to connect to MDD position 6, but i don't really know what 6 is connecting to, just wondering if there would be a preference between 6, 17, 18 or 19?

Update, as it turns out position 6 on the mac connector also has aditional sense wire (thinner orange wire), I wired this wire direct to the brown wire that is connected to position 13 on the FSP connector. I inserted a connector into the FSP loom disconnecting it from position 13.

https://www.fsp-group.com/download/pro/FSP500-50FDB_ME2D.pdf

if memory serves, i do believe that apple pin 14 (+25v trickle) you can run a 12v yellow wire to that and it should work. according to your diagram, you left it empty. as for aux wires to use. when i did my atx mod years ago, i took one of the aux 12v 4+4/8 pin motherboard wires and used them for the extra 12v and grounds to help the mdd logicboard connector