Power Mac G4 Digital Audio Power Supply

For more information, see this article's corresponding Wikipedia page: Device.

Preliminary Information
Leak Risk	High
Batteries	None
Destructive Entry	No

Known Issues

Power Supply

The power supplies in these Macs are susceptible to bad caps, depending on what manufacture of capacitors were used espiecially. A recap may fix these, but sometimes the problem could be with another component that has failed. There are means to also replace the PSU in these Macs with an ATX one, though generally this route will cause you to lose the 24v rail which is needed for ADC monitors to function. Symptoms of PSU failure can include but are not limited to:

• Briefly powering on, then immediately back off (often accompanied by some clicks from the system)
• System only powering on after the PSU has been plugged in for an extended period of time (ex. 2-30 minutes) before attempting to start.

Disassembly Notes

Please be careful when opening the power supply because there are high voltage capacitors inside which can cause great injury to yourself.

AcBel API-9841 REV: B

There are four screws holding the power supply to the case, one on the inside and two on the rear. You will most likely need to remove the DVD bay along with the internal fan under the power supply. Once the PSU has been removed, there are only four screws holding the top case on. Once the screws are removed it will lift straight up. With the top case removed, you will want to unscrew the ground cable, the 115v/230v switch, and the fan. With those removed, there are only three screws holding the board in, two short and one long one. With that, you should be able to remove it from the metal housing, but not completely because of the power socket. You can either work with it connected or desolder the connections. Once I had given it a good inspections, I noticed only one brand of capacitors were visually failing. Normally, I would replace most if not all capacitors, however with this power supply, you will have to desolder at least one of the heat sinks to gain good access to the capacitors. So in the guide I will only be replacing six capacitors, all of which are going to be the Teapo; green/gold coloured branded capacitors.

Original Parts

AcBel API-9841 REV: B

Capacitor Specifications and Footprint Information

Part # on board	Qty	Capacitance	Voltage	Diameter/Size	Height	Lead Spacing	Type	Brand
C10	1	2200 µF	16	13.3mm	24.6mm	5mm	Radial	Tempo
C13/C16/C21/C29	4	2200 µF	6.3	10.25mm	26.3mm	5mm	Radial	Teapo
C39	1	1000 µF	6.3	8mm	15mm	5mm	Radial	Teapo

Replacement Parts

Basic PCB Name

Capacitors

RefDes	Qty	Compatible Part Number	Order Links
			Digikey

If parts are not available or different selection is preferred, you can use the values in the Original Parts section to perform a parametric search.