Mac PSU Question

[Topcat]

A Mac G4 was dumped on me for repair. Caps are fine, but I believe the PSU is dead (has no standby voltage). From the outset, the PSU looks like a standard ATX PSU, as far as it's casing and the 20 pin ATX connector. Is this true? If so, could I use any ATX compliant PSU on it? It belongs to a friend of mine, so I don't really want to cook it.

I'm a complete mac n00b!!

[kc8adu]

Re: Mac PSU Question

iirc it is atx.
just to be safe compare the pinout.
that is if they follow standard colorcode.

[starfury1]

Re: Mac PSU Question

Ok yeah I thought they were using more pc type compatible parts...but with apple you can never be totally sure

Anyway heres a pinout I found

Here 22 pin shown

But as KC8 said Id check it to be sure as there is shown 22 pins in the above

another link shows 24 pin G4 mirrored drives (Quick silver?).

A few links off this site my help

I am not really into macs myself, so not sure of the G4 series and its variations I think the term G4 covers quite a few macs

A note on this Page
and whats written above is why I am always wary of macs

Reminder: The ATX supply does not have 28VDC used on Gigabit G4 and later Towers for ADC. The pinout of the power supply connector/motherboard connector on the Gigabit and later G4s is not the same as earlier Sawtooth models

Anyway hope its of some help TC

one more link

[kc8adu]

Re: Mac PSU Question

must have been thinking of g3
g4 iirc has +28 to run the monitor.

[PeteS in CA]

Re: Mac PSU Question

Not sure whether it was G3 or G4, but there were Mac P/Ss (ca. 1999-2001) produced by Delta where the pin on an ATX P/S used for -5V was used for +3.3V on the Mac P/S. I think Acbel was the other P/S vendor for those projects.

[starfury1]

Re: Mac PSU Question

If this article is anything to go by the G3 b&W shows a
Delta PSU 200PB-106 A Rev 04

ATX ...B&W
-5V = GND
PG = +3V3

Gets a tad confusing as they didn't put pin numbers.
With the +3V3 and -12V on the bottom right

G3 b&W

Here is a link on the "G4/AGP Pre-Gigabit "Sawtooth" Model" Here G4 (page 2 of article)
(does show pinout information)

So it appears the 2 changes are PG signal to +3V3 pin 8 and -5V to GND pin 18

Across the G3 and early G4 sawtooth Apple mac boxes

So Guess you get the Kupie doll PeteS Here
page

I haven't checked any of the links for accuracy so could have it wrong.

anyway HTH

Cheers

[Topcat]

Re: Mac PSU Question

Thanks for all the great info!! I'll look at it closer tomorrow, but I remember thinking I saw something about a +28v rail on the PSU casing, thinking WTF in my head... If that's the case, I'm screwed into buying their f'ing proprietary pile of shit PSU... I knew there was a reason I hated mac's.... :-./

[Rainbow]

Re: Mac PSU Question

Or fix the original one.

[Topcat]

Re: Mac PSU Question

Or fix the original one.

After some brief searching, used ones are going for 100 bucks, so I will give it a try! I haven't dissected it yet, so I have no clue what's wrong with it other than it doesn't do anything..... lol

[starfury1]

Re: Mac PSU Question

If you got the 28VDC its the latter PSU for G4 Gigabit Ethernet (variant)

So its the 22 pin diagram (if I got it right)

Heres Apples page on it for what its worth ("replace the power supply")

G4 22 pin

although you did mention 20 pin in the first post?

There seems to be another 2 variations the MDD (mirrored drive doors, Quick silver)
one being quite different (24 pin)
(MDD is last link in first post)

So you got for the G4 different models, a 20 pin... 22 pin..... 24pin ......*22 pin + 4 pin (so far)
* different again

For reference a PC ATX 20 pin here and Here

PC ATX V2.X (24 pin)Here and Here
(half way down on first link)

BTW I posted the link to "page 2" in both posts wasn't intending too.

Humm yeah postmortem pics would be nice please TC, if you dont mind that is.

So yeah it seems ...... beware of macs and psu's, otherwise you may let the magic smoke out

"Toto... I Have a Feeling We Aren't in Kansas Anymore"

[Rainbow]

Re: Mac PSU Question

I'd check the primary side - fuse, transistors and especially big-value resistors - one is often used to power the controller and goes open sometimes.

[PeteS in CA]

Re: Mac PSU Question

Sawtooth was one of the projects I on which I worked with the folks at Infinite Loop, sf1. It has that user-friendly drop-side case that Apple's EMC department detested. The case is also the reason for the really lo-o-o-ong O/P harness.

IIRC, the +5V Stby uses a Topswitch regulator.