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B&W G3 ATX PS SwapReturn to News Page

PC ATX Power Supply to B&W G3 Swap
By "Red Dragon"
Posted: 9/15/2005

The idea came to me after reading an old article here about converting a G3 B&W into an ATX case. I saw that they used a PC ATX power supply with an extension cable added for powering the logicboard.
(See the "ATX Power" paragraph of that older article for notes/photos on disconnecting the -5V wire from the ATX Power Supply cabling for B&W G3 use. The article includes a note/photo on a low-cost ATX Pwr. Supply extension cable, which added more length to reach the B&W G3 motherboard in that case as well as making it easy to cut the -5V connection and leave the PC ATX Pwr Supply cabling untouched in case you wanted to reuse the supply later for a PC motherboard.
BTW - To head off any mails... I realize that method is a LOT easier than what's done in this article, since you don't need to unsolder any wires in the power supply. This reader didn't have an extension cable to use and instead swapped entire wiring harnesses.-Mike
What I wanted to do was keep the original G3 wires but have the power of an (higher wattage) ATX power supply without sacrificing plugs. So on I went to do a disassembly of the two power supplies.

First the tools of the trade:
-30 Watt pencil soldering iron
-50/50 solder
-a work glove (because the wires do get hot)
-Phillips screwdriver
-wire cutters
-electrical tape
-and a lot of patience
(Solder wick or a solder vacuum tool can also come in handy.)

First, I took a picture to show what the original 200W B&W power supply looked like in a paint modded case.

stock PS rear pix

Both power supplies where the same size, so I didn't have to worry about modding the inside of the machine nor the casings to the power supplies themselves.


The one thing I liked about the B&W power supply was the length of it's cables and the ample amount of molex connectors it had. (Many ATX supplies have plenty of Molex connectors (4-pin HD types) although the number can vary by the PS model. Low-cost Y-adapter cables can also be used to double the number of connections.-Mike)

PS cable lengths

Here is the difference in wattage on both power supplies. The Delta is the B&W and the Wintech is the PC.

B&W G3 OEM Power Supply
BW G3 ratings

Wintech Win-300PS ATX Power Supply
Win300PS ratings

Disassembly was easy on both units. the ATX had 4 outside screws, 4 inside screws and 1 ground to undo. The B&W had 5 outside screws, 2 ground screws and was also held in by 2 tabs along with 1 plastic hold down.

Plasic retainer

Be careful taking off the zap straps off the wires for you may damage the wires.

De-soldering took a long time to do because I was numbering and writing down how many wires altold each power supply had. The B&W had 8 different sets of wires while the ATX had 9 sets of wires.

Here is what both power supplies looked like with the main wires de-soldered.

ps internals

ps internals

Next are the wires themselves. Left is the B&W, and right is the ATX

Here is a drawing schematic to show both power pin outs.

BW G3 vs ATX Pinout

After making sure the wires were going to the proper places on the ATX board, I soldered in the major wires and piggybacked the bigger bunches of wires instead of cutting each wire so it fits into the ATX board. All the wires were now soldered and connected in place.

wires done

After making sure no wires were pinched, I put the casing back onto the new power supply. Here are some pics showing the new revamped power unit.


Putting the power supply back into the machine was fairly easy. The only thing it was not put on was one screw that went into the power supply that held the bracket in place. Since the power supply was the same size as the old one, the bracket fit without the one screw.

PS mtg

Making sure the allen screws fit onto the power supply, I put the wires into the case, and tucked them where they were supposed to go, and closed it up. Interesting, now why didn't Mr. Jobs think of this? A Mac with a power kill switch. (Apple doesn't want the user to be able to instantly turn off the power supply, which could result in corrupted data, etc. if the OS was running for instance.-Mike)

ATX PS rear view

After making sure the wires were all plugged into their appropriate ports, i booted the machine. Got my boot-up sound (i love that sound) and opened up the case to make sure the fans were running. All fans were running and all lights showing the machine booted properly. Here are 2 pics showing the machine booting without a problem.

case cover open

All told, this mod took about and hour and a half. I must say, it's worth it. It gives my old machine new life and more power to work with. I wrote this article while using my new power supply. It's quieter than the previous one...
-"Red Drag0n"

Related Articles:
For other System/Case Conversions, Mods, etc. see the Systems page (organized by mac model/series).
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