MDD Power Supply Recap Success

[Windsor]

Just a quick success story. I picked up a PowerMac G4 MDD 1.25-DP to have as my multipurpose vintage machine. It is the fastest PPC machine I've ever had. But I was a poor student when G4s and G5s were current so they were well out of my price range back then. I kept an Apple laptop, but ended up migrating to PC for my desktop.

I bought the MDD semi-local on eBay for a decent price, listed with no hard drive, does not boot. I was hoping all it needed was a drive. When I attempted to power it on, it would only make noise for a second or so, or it would only click. After poking around it for a minute, it actually powered up! I got it set up with a StarTech IDE to SATA adapter, installed OSes, and so on. It worked for a couple days, but then went back to only clicking.

I built an ATX adapter harness out of a StarTech ATX extension cable, and fought with that for a while because I accidentally omitted one pin. It seemed to boot, but I was getting no display. Seemed like maybe an issue with the ADC card with an ATX supply. But when I got my hands on a couple of my other graphics cards (non-ADC from a Sawtooth and a PCI card from a B&W), I found that those did not work either. Eventually I found my problem with the harness and everything is working again.

In the meantime I was assuming that recapping the power supply would let me work with ADC cards again, so I ordered all the caps from DigiKey. After finding my problem with the ATX setup I had renewed confidence that the machine was actually still good, there wasn't some other problem that was causing the power and display issues. So I sat down and recapped the power supply. It took me over four hours to do, but it was a success. I have a working MDD and I can actually close the case again.

Now what should I do with it?

 

[S. Pupp]

Well done! I looked at the insides of my MDD PSU, said “no way,” and backed away slowly and quietly. I got it fixed professionally, and have obtained a couple more PSU’s in case I get up the nerve to tackle them.

As far as what to do with it?
This is partial list of what I’ve done with mine (purchased new in 2004):
- Made greeting cards using Color-It! paint software
- Digitized TV shows from VHS tapes using a MiroMotion DC30 video capture card (and, earlier, a Canopus ADVC-100 Firewire capture device)
- Made DVD’s of the video captures using Bitvice (or was it Bitvise?) and I forget which DVD burning software
- Digitized my CD collection
- Accessed years of Clarisworks documents
- Played Unreal Tournament and Doom
- Hooked it up to my projector with VGA input to watch DVD’s and play the games mentioned above

It was in daily use from 2004-2018, when it started to become unreliable.

 

[Windsor]

I bought Halo for Mac when it originally came out, but I've never had a Mac fast enough to play it properly. Best I had back in the day was an 800MHz Quicksilver which was on the bottom end of the system requirements for CPU, and I don't recall what I had for a graphics card but it probably wasn't enough. This machine should do it just fine. And I'm considering getting a card from a G5 so that I can get Core Image support. I found an iLife '09 box, but it wouldn't install iMovie without a Core Image capable card. Not that I would have anything to do with iMovie even if I did get it installed...

 

[AndrewG]

really interested in the recaps !
I Just been exploring my duodoc power suppiy unit as I have about 6 these units . and persistent power supply failures . Lucky I came across this site in my search for answers cause I did suspect the caps to be the offenders in older items . Electrolytcs are voltage rated and it seems two caps might be especially vulnerable with 25V 100 Mfarad... One other here noted he replaces with 35V . In general to allow for ac. dc a 50% above rated is recommended . so some logic in placing with 35V. IM doing same as you so hope it will fix . I run a g4 cube also os9.1 with photoshop and its still a good workhorse..

 

[Windsor]

These are the parts I used for the recap, bought from Digikey. The recap took me several hours. Someday I'll get myself a vacuum desoldering tool, would have made the job a lot easier, but I did this with a spring loaded solder sucker.

Index	DigiKey Part #	Manufacturer Part Number	Description	Quantity	Unit Price	Extended Price
1​	1189-450HXW100MEFR18X25-ND	450HXW100MEFR18X25	CAP ALUM 100UF 20% 450V RADIAL	3​	$4.21​	$12.63​
2​	1189-1297-ND	35YXJ220MCA8X11.5	CAP ALUM 220UF 20% 35V RADIAL	1​	$0.46​	$0.46​
3​	478-REF0511470M025KCT-ND	REF0511470M025K	SERIES: REF/ CASE: 0511/ CAP: 47	3​	$0.23​	$0.69​
4​	1189-2577-ND	16ZLS2200MEFC10X25	CAP ALUM 2200UF 20% 16V RADIAL	1​	$1.08​	$1.08​
5​	493-6973-ND	UHW0J272MPD	CAP ALUM 2700UF 20% 6.3V RADIAL	1​	$1.01​	$1.01​
6​	1189-1455-ND	6.3ZLH2200MEFC10X20	CAP ALUM 2200UF 20% 6.3V RADIAL	2​	$0.62​	$1.24​
7​	1189-2566-ND	10ZLS3300MEFC12.5X20	CAP ALUM 3300UF 20% 10V RADIAL	1​	$1.21​	$1.21​
8​	493-5371-1-ND	UPS1HR47MDD1TD	CAP ALUM 0.47UF 20% 50V RADIAL	4​	$0.29​	$1.16​
9​	1189-4003-1-ND	35ZLH470MEFCT810X16	CAP ALUM 470UF 20% 35V RADIAL	1​	$0.67​	$0.67​
10​	1189-1749-ND	35ZLH680MEFC10X23	CAP ALUM 680UF 20% 35V RADIAL	1​	$0.83​	$0.83​
11​	1189-1232-ND	25YXG100MEFC6.3X11	CAP ALUM 100UF 20% 25V RADIAL	1​	$0.28​	$0.28​
12​	493-15842-ND	UPS1H4R7MDD	CAP ALUM 4.7UF 20% 50V RADIAL	2​	$0.28​	$0.56​
13​	1189-2560-ND	10ZLS1000MEFC8X16	CAP ALUM 1000UF 20% 10V RADIAL	2​	$0.60​	$1.20​
14​	1189-4215-1-ND	50YXF10MEFCT15X11	CAP ALUM 10UF 20% 50V RADIAL	4​	$0.26​	$1.04​
15​	1189-4057-ND	16ZLK470M8X16	CAP ALUM 470UF 20% 16V RADIAL	1​	$0.70​	$0.70​
					Subtotal	$24.76​