Powermac G4 DP 1.25ghz not working

[Strimkind]

I emailed a guy a few days ago when his ad appeared in a local classified. He had no price for his non working G4. I offered 20$...he took it but stated he was going to remove the drives. He took them out last night and damaged the back of the case so offered it to me for free this morning.

It is a DP 1.25ghz FW800 with 4 sticks of RAM, a ATI 9700Pro, and 2 optical drives!

Now I am hoping that I can somehow revive it. I hit the PRAM reset switch but no luck. No life in it at all. I do not have a Multimeter so I cannot test the PSU which is suspect.

Still, even dead its a nice conquest!

 

[Byrd]

Nice score, and chances are it's the PSU - seems a very unreliable part in MDDs. ATX time?

 

[Paralel]

ATX may not be much of an option unless he is willing to swap out the graphics card. Turns out the 9700 Pro pulls supplemental power from the +25V ADC line just to function even if no ADC display is attached to it. I haven't read of any implementations of an ATX power supply that are able to supply appropriate voltage to the ADC line.

 

[geeko]

I've heard of attaching an old powerbook psu, that supplies approximately 24v.

viewtopic.php?p=12048#p12048

you can also try to leave it plugged in overnight, I have a single processor 1.25 GHZ MDD that works if it is plugged in for 3+ hours.

ATX might be the better way to go anyway, the MDD PSU is so loud (louder than my eMac was)

http://www.applefritter.com/node/23857 also take a look at that

 

[Strimkind]

Upon closer inspection, the video card is actually a (800 Pro rather than a 9700 pro. It does not have the ADC port so would not use the +24V line. This makes the ATX Adapter a better option...mind you I have never done it before. I may still look for a MDD PSU for cheap at a local computer store.

 

[Byrd]

So being a 9800Pro ... suggests it is a flashed card?

 

[Bunsen]

It does not have the ADC port so would not use the +24V line. This makes the ATX Adapter a better option...mind you I have never done it before.

As mentioned in the thread linked above, I did the ATX hack on a G4 DA. +5VSB connected to the 24V pin was enough to get it to boot. The only other thing you lose is Firewire power, but a powered hub would add that back if you have any bus-powered devices.

If you go this route, I suggest getting an ATX extender cable or P4 adapter cable and hacking that up, so you can exchange any ATX power supply without modification should you need to. Also, spend the extra $5-$10 and get the tool for removing pins from those ^%$*&%*^% power headers. I used a pair of tweezers ground down thin enough to reach in and press the release tabs inside the wire holders, but it was still a PITA. Mark II of that tool if I ever need it would probably be made out of a small piece of steel/copper tubing just larger than the crimp connector.

 

[Paralel]

Does anyone know how many volts a 9700 Pro pulls through the supplemental ADC line just to function? It could easily be greater than 5V

 

[~Coxy]

I doubt that it would pull any power unless an ADC monitor was plugged in?

 

[Paralel]

No, it does. The 9700 Pro pulls supplemental power from the ADC line just to function even when an ADC monitor is not connected to it. If you try to use a 9700 Pro in a MDD with an appropriately rated ATX power supply that is wired correctly except it lacks the +25V line you won't get any video output.

It's not too surprising. The PC version of the 9700 Pro also needed supplemental power, but that was supplied by a floppy power connector. I would imagine the ATI engineers figured it would just be easier to pull from the ADC line to power the card since the stock MDD power supply had no floppy power connectors.