PowerMac G4 MDD

For more information, see this article's corresponding Wikipedia page: https://en.wikipedia.org/wiki/Power_Mac_G4#3rd_generation:_Mirrored_Drive_Doors/FireWire_800.

This device is in the WorkNeeded:OriginalParts category because it was flagged as missing information on the original parts. It may have replacement parts listed but those cannot be assumed to be identical to the originals. If you have a list of the original parts, please feel free to add them by copying the relevant table from EditorsToolbox:Tables

The G4 MDD is the third and final generation of Apple's Power Mac G4s, named so due to its Mirrored Drive Doors. It was produced from 2002 to 2004, and is notable for being one of the last Macs capable of running Mac OS 9 (with some caveats).

PowerMac G4 MDD

Preliminary Information
Release Year	2002
Leak Risk	High
Batteries	One (1) PRAM Battery
Mounting Technology	Through Hole, SMD, BGA, Sockets
Capacitor Types	Aluminum Electrolytic
Destructive Entry	No

Known Issues

Power Supply

The power supplies in these Macs are known for suffering from failed capacitors. 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 (10-30 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.

NOTE: If you are replacing the PSU fans while you're inside it, pay close attention to the CFM of the replacement fans, and match the original fans! Otherwise you may cause your newly recapped PSU to overheat and fail.

AcBel API1PC36

There are 5 screws holding the housing together and 4 screws holding the fans that need to be removed. Once the screws are removed, the top part of the housing needs to slide away from the fans. After that, the fans can be disconnected from the fan control board (though they may be zip tied to adjacent cables).

There are four screws around the perimeter of the main board, after those are removed the board should be mostly free, though you may get hung up on a filter cap that's behind the AC input. This cap is only adhered to the board, not soldered to anything, so it can be broken free of the main board without having to worry about desoldering anything. At this point the board should finally be free enough to slide it out and flip it over to desolder the two wires going to the AC input, take note of the orientation for reassembly.

The fan controller board has capacitors on it that may need to be replaced (this is where C401/C402/C403/C405/C407 are located). Even if they don't, it is recommended that this board be desoldered and moved out of the way to allow easier access to the capacitors behind and around it, as these do need to be replaced. The fan controller board is held in with both solder and a decent amount of adhesive, it may prove difficult to get it free of the main board even once the solder and most of the adhesive has been removed.

Samsung PSCF401601B(C) Rev. B

Note: Documentation on this PSU is a work in progress.

With the Samsung label facing you, and the cables coming out of the bottom, there are:

• Three screws on the top side
• Three screws on the bottom
• A single screw on the back, close to the AC input
• A single long screw between the two intake fans, nearby the screw hole to mount the PSU inside the MDD (This is a long, fine thread screw. If you see a thick, coarse thread screw typical of a fan screw, you've got the wrong one.)

Once those are removed, lift the top (the part with the Samsung label) slowly away from the bottom half, lifting from the fan side.. You'll need to disconnect the the two fans from the main PCB, and they'll come away with the top half of the PSU. The AC input isn't soldered in, it can be disconnected from the main PCB. You'll also need to remove a screw that secures the ground wire to the rest of the PSU. At this point the top half should now be completely free and can be removed.

There are three screws around the perimeter of the PCB (one of them was the grounding screw) and a plastic rivet in the center of the PCB holding it to the bottom case. This rivet is easily defeated with a set of forceps or needlenose pliers and a careful hand: Reach in with your tool of choice, pinch the rivet and lightly pull up on the PCB as you do. The rivet should pop through the PCB and the PCB itself should now be free of the bottom metal casing.

Original Parts

AcBel API1PC36

Capacitor Specifications

Part Number on Board	Capacitance	Voltage	Diameter/Size	Height	Type
C3, C4, C5	100 µF	450	0.7"	1.6"	Radial
C7	220 µF	35	0.3"	0.64"	Radial
C8, C32, C401	47 µF	25	0.18"	0.46"	Radial
C10	2200 µF	16	0.4"	1.2"	Radial
C13	2700 µF	6.3	0.4"	1.1"	Radial
C16, C29	2200 µF	6.3	0.4"	0.9"	Radial
C21	3300 µF	10	0.4"	1.2"	Radial
C30, C55, C56, C402	0.47 µF	50	0.2"	0.45"	Radial
C35	470 µF	35	0.4"	0.8"	Raidal
C41	680 µF	35	0.4"	1.2"	Radial
C43	100 µF	25v	0.25"	0.45"	Radial
C53, C57	4.7 µF	50	0.2"	0.45"	Radial
C59, C60	1000 µF	10	0.325"	0.76"	Radial
C403, C405, C407, C45	10 µF	50	0.2"	0.45"	Radial
C416	470 µF	16	0.32"	0.6"	Radial

Samsung PSCF401601B(C) Rev. B

There are two daughterboards inside this PSU, and one of them (the inner one that sits next to one of the big heatsinks) must be removed to access the three caps that sit behind it, in addition to the two caps that are on the daughterboard itself. The outer daughterboard that sits near the edge of the PCB can probably be worked around, but I found it easier to just remove it from the main PCB.

Main PCB

Part Number	Capacitance	Voltage	Diameter	Height	Lead Spacing	Type	Notes
C122	390 µF	420	35mm	42mm	12mm	Radial
C209, C210, C213, C214, C251	2200 µF	10	10mm	24mm	5mm	Radial
C204, C205	2200 µF	16	10mm	30mm	5mm	Radial
C207	470 µF	16	8mm	12mm	3.5mm	Radial
C208, C363	100 µF	16	6mm	12mm	3mm	Radial
C236	10 µF	50	5mm	11mm	2.5mm	Radial
C223	470 µF	35	10mm	20mm	5mm	Radial
C222	1000 µF	35	13mm	25.5mm	5mm	Radial
C135, C137	56 µF	35	6.5mm	11.5mm	3mm	Radial	These caps require the removal of the inner daughterboard to access, as they sit behind it.
C141	47 µF	25	5mm	11.5mm	2.5mm	Radial	This cap requires the removal of the inner daughterboard to access, as it sits behind it.

Inner Daughterboard (Next to heat sink)

Part Number	Capacitance	Voltage	Diameter	Height	Lead Spacing	Type
C129	10 µF	50	5mm	11.5mm	2.5mm	Radial
C130	22 µF	50	5mm	11.5mm	2mm	Radial

Outer Daughterboard

Part Number	Capacitance	Voltage	Diameter	Height	Lead Spacing	Type
C364, C365	22 µF	50	5mm	11.5mm	2.5mm	Radial
C241	2.2 µF	50	5mm	11.5mm	2.5mm	Radial
C375 (UNPOPULATED)	N/A	N/A	N/A	N/A	N/A	N/A

Notes:

Pay close attention to the outer daughterboard caps! There's a 22 µF cap right next to the 2.2 µF cap, and it's all too easy to mix these up with how small the text is.

C375 was unpopulated on my board. It's only noted here in case you go back to check your work, in case you mistakenly think you forgot to put a cap there.

Replacement Parts

ACBel API1PC36

Capacitors

Part Number on Board	Qty	Compatible Part Number	Order Links	Untested alternative replacements
C3, C4, C5	3	450HXW100MEFR18X25	DigiKey Mouser
C7	1	35YXJ220MCA8X11.5	DigiKey	REF0812221M035K (Mouser equivalent)
C8, C32, C401	3	REF0511470M025K	Mouser
C10	1	16ZLS2200MEFC10X25	DigiKey Mouser
C13	1	UHW0J272MPD	DigiKey Mouser
C16, C29	2	6.3ZLH2200MEFC10X20	DigiKey Mouser
C21	1	10ZLS3300MEFC12.5X20	DigiKey Mouser
C30, C55, C56, C402	4	UPS1HR47MDD1TD	DigiKey Mouser	Wurth 860160672001
C35	1	35ZLH470MEFC(T8)10X16	DigiKey Mouser
C41	1	35ZLH680MEFC10X23	DigiKey Mouser
C43	1	25YXG100MEFC6.3X11	DigiKey Mouser
C53, C57	2	UPW1H4R7MDD	DigiKey Mouser	ESH475M050AC3KA
C59, C60	2	10ZLS1000MEFC8X16	DigiKey Mouser
C403, C405, C407, C45	4	50YXF10MEFC(T1)5X11	DigiKey Mouser	EEU-EB1H100SH
C416	1	16ZLK470M8X16	DigiKey Mouser	16YXJ470M8X11-5 or REF0816471M016K*

NOTES

"Possible active replacements" refers to active replacements for parts that are marked as obsolete/obsolete and out of stock, or parts that have reached "last time buy" status. These have not been tested, only found by doing a search for the closest match to the original replacement parts listings. Some of these may be higher voltage than the original caps, this should be fine.

For C416: The lead spacing might be off for this one, but it should, in theory, be fine. There are two different caps listed here in case of store preference. The Rubycon 16YXJ470M8X11-5 is available at Digi-Key, but not Mouser. The Kyocera-AVX REF0816471M016K however, is available at both.

Related Links

• https://www.badcaps.net/forum/showthread.php?t=83705&highlight=mac+g4&page=3