MDD Power Supply options

[chrisdunderdale]

Hello again,

I have just picked up a dead MDD Dual 1.25 2003 (bootable OS9, FireWire 400, etc) that I would like to get working. I am assuming the power supply is dead, as other components I have tested seem to be working fine. I was wondering if it is possible to repair the original power supply, and this way I can retain the ADC capability, rather than putting in an ATX version. Or, is it simply not worth the hassle, and I should just go with ATX. Interested in your thoughts!

 

[s_pupp]

I opened a dead Samsung MDD G4 PSU, looked at the chaos within, and said “Nope!” If you are in the US, there’s someone on eBay who fixes MDD G4 PSUs for about $90. I sent mine to him.

My other MDD G4 has an ATX PSU mounted outside the case. It doesn’t look great, but the Mac is much, much quieter.

edit: ACX Electronics is the eBay MDD G4 PSU repair company.

 

[chrisdunderdale]

Ah yes, ok - I think would also feel the same about trying to fix the power supply! Sadly, I am in the UK and don't think there are any services for fixing these power supplies. I might have to wait about on here to see if anyone has a spare power supply they would like to sell.

 

[ObeyDaleks]

I don’t know if you have ever listened to a working stock MDD PSU, but they are insanely loud. That’s the main reason I prefer an ATX conversion for the MDD.

 

[chrisdunderdale]

Yes, I used to have one back in the day as an edit machine. I would also prefer to do the ATX conversion for the noise, but I wouldn’t want to loose the ADC capability. Is there a way round this?

 

[cheesestraws]

Stick an extra boost converter in there for the higher voltage? I'm not sure what the amperage requirements are, but boost converter modules generally aren't that hard to find

 

[MOS8_030]

After replacing two stock PS's in my Dual 1.25 MDD I installed an ATX PS. It's been working great for several years.

 

[ObeyDaleks]

Yes, I used to have one back in the day as an edit machine. I would also prefer to do the ATX conversion for the noise, but I wouldn’t want to loose the ADC capability. Is there a way round this?

I think I researched it briefly back in the day and I couldn’t find an easy way to preserve ADC. But I wasn’t too worried about it since I was upgrading to a DVI graphics card anyway. You can always use the DVI to ADC power brick. I assume most people go this route when converting to ATX (and want to use an ADC monitor).

 

[chrisdunderdale]

Ok thanks All. I think I will go the ATX route then. There is a resource that lists suitable power supplies somewhere right?

 

[GRudolf94]

Personally not a fan of ATX on MDDs just because of how jank it always ends up being. Mine retains its stock (repaired) PSU, with some quieter (if less durable) POM sleeve bearing, instead of ball bearing, fans. The issue is that moving air makes noise, and the stock PSUs are long and tightly packed, so you can't go much quieter.

I think it's part of the price to pay for owning that machine, and changing too much detracts from it.

 

[chrisdunderdale]

I’d agree with that - if only there was somewhere in the Uk that repairs them. I haven’t been able to find anything as of yet.

 

[Plasticoat]

This is how I began my journey, no one was able or willing to repair my classic, so it began…

I have 2 PSU for a G4 , after years I have started to map and remove old capacitors, but it may take another 2 years before I have completed the job.

In between jobs I have a quicksilver to tide me over so I’m in no rush, this listing may help it’s £1

Apple Power Mac G4 Spares or Repairs NO HARD - FAILED HARD | eBay

This Apple Power Mac G4 desktop computer is being sold for spares or repairs. Please note that the hard drive has failed and is not included. The computer may have other issues and is being sold as-is. This tower model was released in 1999 and features a PowerPC G4 processor and ATI Rage 128...

www.ebay.co.uk

Start the journey, you never know where it will take you

 

[cgp]

The ACBel PSU on my G4 failed several years ago and I tracked down and replaced the failing cap thanks to threads over at badcaps.net. Search or start here for guidance:
https://www.badcaps.net/forum/troub...4-mdd-acbel-power-supply-issues-api1pc36-400w

In my case, it was a starter cap on the hot side of the regulator.

You do have to be a little careful of the 400V thereabouts which doesn't decay immeditately on power-down.