G4 MDD PSU

[AlpineRaven]

I've got this G4 MDD (Mirror Drive Doors) FW400 1.42ghz, it's a such a good workhorse and fastest genuine Mac/last Mac to be able to run Mac OS 9.2.2 and OSX, and it has been beefed up with heaps of upgrades (ie. SCSI, Sonnet SATA, GPU etc), to date it has been working very well and I need to look after it.​

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Number one I need to focus is the Power Supply....​

It has Samsung PSU from G4 MDD FW800 in it, I am hearing reports that they do go, I want to rebuild it before it goes. Any suggestions re; rebuilding it?​

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Cheers​

AP​

 

[Trash80toHP_Mini]

edit: when I started this particular links project eight years ago, the failed PSU issue wasn't all that big a deal. I checked eeun's 'fritter thread about the MDD, can't vouch for the rest of the links.

There have been quite a lot of threads posted about these issues in the various model specific forums over the last year or two. If anyone running across one would link to the first post as above in the ATX Gazette, the new additions will surely prove to be helpful to others in the future.

 

[Trash80toHP_Mini]

I'm in the process of setting up the ultimate OS9 machine for when the QS'02 craps the bed, so I'll be following your progress with great interest.

IIRC, someone was fabricating cables for this type conversion. Dunno if they're still available, but pics of his simple production jig and the pinouts were well documented. ISTR it being a thread over on the highly recommended OS9lives forums?

 

[OleLila]

Any news or follow up on the silver door G4 power supply repair or replacement successes?

 

[OleLila]

Going to try this

https://www.amazon.com/gp/product/B01NBU2C64/ref=ppx_yo_dt_b_asin_title_o04_s00?ie=UTF8&psc=1

and this

http://atxg4.com/mdd.html

To any electricians out there, if I used a separate DC power supply of 25 volts to pin 14 in parallel with the atx power supply could I still use the adc power for adc monitors?. If the dc supply pugged into the same outlet as the ATX are they grounded the same? 

 

[davidg5678]

I wonder if you could use a voltage boost converter on one of the PSU's 12V lines and boost the voltage to the 25V the ADC screens run on. Maybe a product like the one below would work? I think the limiting factor for getting this to work is current and not voltage, but in theory, an ATX PSU should be able to provide enough?

https://www.amazon.com/WHDTS-Converter-Display-Adjustable-Constant/dp/B07L5KNBCN/ref=sr_1_2?crid=UKYCIOPU9PKP&dchild=1&keywords=boost+converter&qid=1596737673&s=industrial&sprefix=boost+c%2Cindustrial%2C137&sr=1-2

 

[OleLila]

My video card is full length, it’s looking like the largest power supply I’m going to be able to put in and get the case closed (and keep cost under 40 bucks)  is 350 watts. Searches say this if ok if you are not using adc to power a monitor. Still have to build the cable and test it on a 500 watt power supply before springing for a 350 watt to fit in case. 

 

[MOS8_030]

I did an ATX swap in my MDD a couple of years ago. It's still working fine.

 

[OleLila]

Thanks for the link it was very helpful, sorry to repeat  up information that is already out there. ....I have the same video card that you have and it inspired me to reassess and I found that I can shut the case with the 500 watt power supply mounted in that area. So the power supply swap worked.....on with the original power button, resets with a power button hold down, used an external power adapter for the display. The ATX to MDD adapter board was handy primarily  because it has a standby/on button that allows you to turn on the power supply and test all of the voltages on the MDD molex before plugging into the logic board. However it is bulky and to close the case with it in place I will have to leave out the hard rives opposite of it to make room. 

If the power supply If the power supply you have has colored wires, I'd opt for the molex removal tool instead. Some of the descriptions sound like a wire to wire swap (just changing the location of the pin connectors) but I did have to double up on a 5 volt and 12 volt connection. I put a jumper wire from ATX pin 8 (power OK) to ATX pin 2 (3.3 volt ) then attached that to pin 18 of the MDD, this is described in the link above. I cut off the "plus 4" portion of the 24 pin atx connector and plugged in one of the CPU 4 prong connectors from the ATX power supply in its place to get 2 additional 12 volt connections.  The MDD needs 4 pins on 12 volts so I attached 2 of the 12 volt lines to one of the  12 volt lines now available from the ATX cpu power (one of the 12 volts now in the "plus 4" portion of the cable).