Fixing A Dead PSU From A G4 MDD

[2112st]

This is a little off-shoot from the thread I started about my G4's problem. I'm just curious if any of you folks have tried this, given this power supply's issues with the MDD...

Have any of you done an autopsy on a dead PSU from an MDD? If so, have you tried resurrecting it (recapping and whatnot)? If so, what have been your results? What caused them to fail in the first place?

 

[Nixontheknight]

I think most people just replace them with modified ATX power supplies

 

[2112st]

I think most people just replace them with modified ATX power supplies

I know, but some of the more adventurous among us like to do that deeper dive-I'm not in that group, LOL. I'm simply asking out of idle curiosity.

 

[S. Pupp]

I’ve been adventurous with electronics since age 7. Any time anything I own breaks, I try to fix it. I’ve recapped power supplies for my SE/30, and two IIfx’s. I’ve recapped logic boards for PowerBook G3 and G4. I’ve worked on my MacBook Pro’s logic board.

I took one look inside the MDD PSU, however, and said “Nope.”. It’s a really tight mess in there.

I ended up sending two of them to ACX Electronics on eBay. He got them back to me quickly, and they now work fine. My main MDD, though, has an ATX PSU sitting outside the case, with a home-assembled ATX to G4 MDD extension cable. It is quiet, and the cpu reports lower temps.

 

[trag]

The badcaps forum has (or had, it's been years since I looked) a few threads on repairing the MDD power supply.

https://www.badcaps.net/

 

[S. Pupp]

Good resource, trag. A search for “MDD G4” at badcaps.net leads to several pages of results regarding both brands of PSU. I used badcaps.net in the past to fix a Sony receiver, but for some reason it’s never occurred to me to check it for Mac related issues.

 

[speakers]

Several years ago, I repaired my API1PC36 REV:A PSU using badcaps.net resources. For me, it turned out to be a starter cap in the primary circuit.

https://www.badcaps.net/forum/troub...4-mdd-acbel-power-supply-issues-api1pc36-400w

Watch out for the high voltage that doesn't decay too quickly in these guys, though!!