Quicksilver G4 using an ATX Power Supply?

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Hawaii Cruiser's picture
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It's been discussed earlier, but I'd like to narrow this topic down to a clear consensus. Can you use an ATX PSU to power a Quicksilver without having to supply the +28v (actually +25v ?) input to pins 9 and 22 as diagrammed here and here? --Except on the OutOfSpec page he clearly states that you'll need an extra wallwart power supply to provide something close to +28v for the two pins (which is also added to this kit). But you only need the full 28v in order to power an ADC, right? Otherwise, a lesser voltage will suffice which can all be provided by the ATX alone. This would also explain this ridiculously priced "adoptor"(you have to cut them some slack on the spelling, they're German, just imagine Austrian Arnold Schwarzenneger pronouncing it).

From what I'm reading in different threads here at 'Fritter, a few people are stating that you only need 12v to pins 9 and 22, so all you would have to do is tap 12v from other lines on the ATX PSU, or simply from the P4 four-pin connector on newer ATX PSUs. You could use a 20 pin to EPS12 24pin extender, or a simple 20 to 24pin ATX extender to safely make the mods. Am I following correctly so far?

Now, where I'm getting confused is that I'm also reading, as in the last posts on alk's thread that there is also the suggestion that, instead of 12v, you can even use +5v as an alternative. Does this actually work? It is stated there by stewart710 that the +5vSB is actually preferable since it is always on standby. +5vSB is already coming into pin 9 on an ATX PSU. But will that +5vSB be needed for pin 22 rather than pin 9? And then, pin 9 requires at least 12v? The "white" lead on pin 22 is the trickle, right? So the standby line would be optimal for pin 22 because the trickle alerts the motherboard to a power on? And pin 9 provides power to the ADC, so it would need at least 12v to convince the motherboard of its adequate performance, correct?

So here's the synopsis as I'm concluding it. The ATX's pin 9 +5vSB line needs to be transfered to pin 22, and then pin 9 needs to tap into a +12v line, assuming you're not going to be using an ADC, which I won't be using. And then, pin 11 needs to tap a ground. It's as simple as that.

Am I getting all this right, or am I simply totally confused? thanks

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Joined: Oct 19 2004
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yes i am very interested in t

yes i am very interested in this as well, as I am thinking of building a G4 GIG from parts.

You can put one together off of ebay for less than $100.

James

Hawaii Cruiser's picture
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Joined: Jan 20 2005
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+5vsb stabilizer?

How about a stabilizing capacitor soldered onto the +5vSB line?:

Stabilizing Capacitor on +5vSB line

A good idea?

Eudimorphodon's picture
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Joined: Dec 21 2003
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Re: +5vsb stabilizer?

Hawaii Cruiser wrote:

How about a stabilizing capacitor soldered onto the +5vSB line?:

Unless you found your power supply in a box of Cracker Jacks or the computer is plugged into the same circuit as your drill press a Lifesaver Candy taped to the +5v line will have roughly the same impact on the computer's operation. ;^)

--Peace

DrBunsen's picture
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Isn't the +28V needed for any

Isn't the +28V needed for any bus-powered Firewire devices as well?

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Joined: Mar 18 2008
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Hi folks! Yes i tryed that. B

Hi folks! Yes i tryed that. But it wont work. You can not avoid +28v!!! So buy an PSU +28v for something like $17 and follow http://www.outofspec.com/frankenmac/wire.shtml I have a MAC quicksilver standing behind me and it is working good now. But it was dead for smth. like 1 year since PSU died after the power off. Have a good luck!!!!!!!!

DrBunsen's picture
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I can't answer for a QS but m

I can't answer for a QS but my DA is running just fine with +5VSB on the +28V pin.

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eeun's picture
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Re: I can't answer for a QS but m

DrBunsen wrote:

I can't answer for a QS but my DA is running just fine with +5VSB on the +28V pin.

Have you found anything that doesn't work properly other than possibly firewire bus power?
What's the total wattage of the PSU you're using?
Just curious...I figure my DA might need a new PSU one day. I've yet to make use of firewire on any computer I've owned, so I think I can live with a slightly crippled bus if necessary.

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