Any interest in MDD ATX PSU conversion?

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eeun's picture
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I've just picked up a mirror-door G4 for cheap, sold as a "won't power on" unit.

After a quick test, and it does power up with a re-wired ATX power supply.

I picked up a better PSU, with a rating closer to that of the original, and wanted to know if there was any interest in having the process documented.

There isn't too much out there on mirror-door to ATX conversions, despite their flaky power supplies, so if there's some interest, I'll snap some photos while I'm doing the wiring and installing.

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Hawaii Cruiser's picture
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links

I put together a little list of links on this thread:
http://www.applefritter.com/node/23054

I'd like to see how you solve the ADC power problem.

IIRC, the original MDD PSU's were prone to some kind of problem. Noisy for one thing. There was an Apple rebate for a new one or something like that? Their PSU's are long and shorter right? So will getting a taller ATX into the case bracket be possible?

eeun's picture
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Re: links

Hawaii Cruiser wrote:

I'd like to see how you solve the ADC power problem.

Ain't gonna ;D

From what limited info I've found on the MDD conversion, the 28V is only necessary if you're going to use the ADC conector, and probably firewire. I'm not planning to do either.
I just picked up a PSU, and tomorrow will start work.

I'll also post the links I've found once I'm at my home computer, and that'll answer your other questions.

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As I understand it from the o

As I understand it from the other threads, the G4 towers will not turn on unless there is some power coming into the ADC pin. It seems to be debatable, though, how much power is necessary. Some were saying at least 24v and someone else was saying it needs only 5v. Check the other threads I linked. I don't know, and maybe you do, if the MDD is somehow different, or you know of some special hack. A 5v minimum would be an easy tap into another line, but the 24v would require a wall wart or something similar coming in externally.

eeun's picture
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This MDD has no trouble booti

This MDD has no trouble booting without power to the 28V line.

I've got the wiring loom finished and have now booted to the finder with a 10.4 backup drive I had kicking around.

Pics soon...

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eeun's picture
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photos

Here's where I started:
(thumbnails are clickable for larger image)
MDD to ATX - old PSU
One dead MDD power supply. When I opened it up, I found the fuse was blown. Tried replacing it, but the new fuse blew as soon as it was connected to the mains. There's nothing visibly wrong that might have been an easy fix, and the PSU is pretty densely packed and has a lot of silicon caulk applied to keep components from shifting. Better to start from scratch...

MDD to ATX - extension
This is the ATX extension I'll be using for the connector. I'd considered cutting the ATX connector off the new PSU and soldering wire to loom from the MDD PSU, but thought this would be a bit cleaner and gives me the option of salvaging the new PSU if something goes wrong.
MDD to ATX - connector
The wiring loom has been cut from the old power supply, and is ready for soldering. I used heat-shrink tubing to cover the solder joints. It's nicer looking than my old stand-by, black tape, and makes a stronger connection.
I picked up a 500W Cooler Master PSU that has a nice 120mm fan and an open grill at the back that should allow for good ventilation inside the case. The PSU will be mounted above the optical drives...which is as far as I can tell the only place a regular size ATX PSU will fit in that case.
MDD to ATX - wiring loom
The wiring in progress. After double-checking the wiring here and here, it's down to connecting the right colours together.
There are more 3.3V and 12V lines on the MDD PSU than are provided by the ATX PSU, so I've attached two MDD wires to one ATX wire in a couple of spots.
The only issue I had here was the 4-pin extension. I didn't have a female connector for that, so I relented and cut the ATX supply wires and used some spare wire to make an extension that would keep those 4 wires the same total length as those going through the ATX connectors.
If I need to salvage the ATX PSU at some point, it's only 4 wires to reconnect.

And the link where I got my inspiration from:
http://efeion.blogspot.com/2007/12/power-supply-fun-part-2.html

Stay tuned for the next chapter: Drilling, Fitting, and Hooray for Cable Ties!

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Update - installed

I've now got the power supply installed.

Based on the Twilight in Efeion blog linked above, and from my own test fitting, a regular ATX PSU will not fit in the case anywhere except above the optical drives.

I decided to use cable ties, as they're strong enough to do the job, and easier than making brackets and using rivets or tapping threads in the case metal.

With the case on its side and the motherboard up out of the way, I drilled four 7/32" holes, roughly eyeballed to where the case will be sitting underneath. I made a starter hole using a small bit first, as a larger bit will wander around the case metal before getting a bite.
The case was given a good vacuum and any metal flash still stuck to the drilled holes was knocked off. Don't want little bits of metal falling off onto the mobo once it's all back together!
MDD to ATX - power supply

It took six cable ties in total to wrap around from the top to join up under the PSU once it was in place. Cable ties do chain together nicely.

MDD to ATX - power supply mount

A view from the inside of the case.

MDD to ATX - psu mounted

Installed!
I threaded the power cord through where it would have connected to the old PSU. That's got to be addressed, as I want the G4 to look stock from the outside. I've got an idea for that...

One more check of the wiring, and then I transfered over my two hard drives from my Digital Audio G4.
OS X 10.4.10 boots fine, but waitaminit...OS 9 won't boot! What's going on???
Turns out the Mirror-Door G4 had its own special install of OS 9 and none other will work with it. Fortunately, I found I had the two-DVD install/restore discs kicking around.
I didn't want to mess up my OS 9 drive, so I installed the MDD OS 9 to a spare drive, then copied over just the system folder to my work drive. All better now.

Nearly done. Just have to work out that power supply connection to the outside of the case.

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Looks great! That's intere

Looks great!

That's interesting, you're saying the MDD will only boot a machine-specific OS 9? Any idea what's the difference?

I get lost trying to hold the pinouts in my mind, especially as it requires a mirror image at the same time. So the white wire pin 14 is the ADC pin, and you've got 12v going into that? 12v is chosen because there are some video cards that draw power from that line, if I'm reading the linked page correctly. So is it, yes, some power has to be going into that line or else the machine won't turn on, and 12v is the safe minimum?

How about placing a fan on the back grill? Have you checked heat?

eeun's picture
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questions...

Had a question PMed about this, but thought the info would be good to share here...

My MDD logic board has only the one power connector - the big 24-pin ATX style connector. The FW800 MDD boards may be different...anyone know?

The video card clears the bottom of the ATX PSU with maybe 3/8" to spare. That's the reason the PSU is suspended from the top of the case: the video card would otherwise hit it.

There's enough clearance for smaller cards - I have a SCSI card installed, and my USB 2.0 card fits, too, but I may not install it as it prevents the Mac from deep sleeping.

Speaking of which...that may be an issue I'll face with this conversion. I did read there may be problems bringing the Mac out of deep sleep without that higher voltage line. I'll have to try it and see...

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eeun's picture
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Re: Looks great! That's intere

Hawaii Cruiser wrote:

Any idea what's the difference?

I'm going to guess it's the memory controller, since the MDD uses DDR.

Quote:

So the white wire pin 14 is the ADC pin, and you've got 12v going into that?

Yep, white is the 28V line. And nope, I've connected it to nothing. It's an empty connection on my setup. This may be a particular anomaly of the MDD Macs, as I do remember one of our earlier threads noting the DA and QS Macs need something on that line to work.

Quote:

How about placing a fan on the back grill? Have you checked heat?

Haven't run anything heavier than an hour's worth of Orbital 1.0.2, a planetary orbit simulator that's a great big bag of fun. CPU temperature topped out at 35.1C according to Temperature Monitor.
Everything's nice and cool inside the case when I opened it up immediately after shutting down.
For those unfamiliar with the case design, there's a huge opening under the front 'foot' of the case to let air in. I've now got two 120mm fans - the one stock fan in the lower half of the case, and one in the new PSU - pushing air towards the back. I considered adding some sort of duct from the back of the new PSU to the rear of the case, but I'll keep monitoring the temperature, and if it needs extra cooling, a fan on the back grill is a good choice.

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Finished - probably

I've now finished the power supply, and the power cord plugs into the original location on the back of the G4.
MDD to ATX old PSU case
Looking at the orignal power supply parts, I thought I'd be able to cut the casing up and connect a spare power cord to the old power connector.

note: to anyone considering this, the rest of this post deals with 120 VAC wiring, and care should be taken. Don't try this if you don't have experience with AC wiring. You can not only fry your computer, but yourself as well.

MDD to ATX - plug parts
Here's the old casing cut up, and the cord that will lead from the ATX supply to the back of the case.
I used a jigsaw to cut the old case, then filed any flash and sharp edges with a file.
The cord is a right-angle one from a monitor, which should give me some extra room around the PCI slots.

MDD to ATX pigtails
Wire splices are done...in my case the two hots were black on the cable, and brown on the PSU; white and blue for neutrals and two greens for the ground. Verify your connections with a meter! Don't just trust the colours when working with 120 volts.

MDD to ATX - plug finished
...and supported with cable ties. The pigtail connectors have also been wrapped in black tape for extra protection. The cable ties should prevent the pigtails from being moved or stressed.
There's only one hex-head nut that threads in from the back of the case to hold this on. Seems strong enough for me, but it wouldn't hurt to reinforce it.

MDD to ATX - plug installed
Not much to see once it's installed. The wiring is hidden and protected by the old PSU's casing, and it looks stock from the back. Larger PCI cards will hit the power supply, but my SCSI card clears it and the power cord.

MDD to ATX - finished
Back in business!
It looks completely stock from the outside, and I've managed to upgrade from my 867 MHz overclocked DA to 1.25 GHz with a faster bus speed for a very reasonable price.

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Nicely documented

I just completed your PSU harness mods on a dead MDD. It works perfectly. I have yet to mount the ATX supply, but that will happen shortly. I'm thinking of running the ADC power line and am wondering whether the it is needed for use with an ADC to DVI converter? Is the 24V just passed through to an ADC monitor or is it needed for the video signal conversion? Any ideas or hints most appreciated.

Regards,
Brent

eeun's picture
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Glad the writeup was helpful!

Glad the writeup was helpful!

As far as I know, the 24V is for powering the Apple Display monitor. Not knowing the ADC to DVI converter, though, I really can't answer one way or the other.
I don't have any firewire devices, either, so I'm not sure if the 24V is used for that on the MDD. I know it is on other G4 models.

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update?

Hi Eeun, now that you've had a few months to run this setup, I was wondering how it's been working out? Any anomalies to speak of, or is it all still running smooth and no overheating?

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It's been fine. Temps are sti

It's been fine. Temps are still going no higher than upper 30s C, though I expect they'll rise a bit when we get warmer temperatures.

All very boring, actually. It's easy to forget that I've made any modifications to it.

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Don't know what you're missing

You'd probably be much more appreciative of your own handiwork here if you had first had the experience of a working MDD OEM PSU. We picked up a dual 1.25Ghz MDD and the noise level of the PSU, while not what I'd call annoying, is definitely intrusive. It has a real affect on the work environment, so this mod is very tempting.

I stumbled on this website which seems to have just about everything you need to know about PSU's and noise and performance. Looks like it's got a large database of reviews of the various branded PSU's with good details and photos:

http://www.silentpcreview.com/

It's got a good primer on PSU's here:

http://www.silentpcreview.com/article28-page1.html

And then there's a section on recommended PSU's, although the recommendations of any site which has extensive related advertising is always suspect, but this site looks pretty "out-front."

Thanks for your story. It's very helpful!

I thought I'd throw a link here to another AF thread about the MDD interior which is running in tandem with this one:
http://www.applefritter.com/node/23903
Some concerns intersect.

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Not knowing anything about th

Not knowing anything about the power supplies. Would it have been easier to use another Apple power supply? That is on from an Xserver or Quick Sliver? Would they have had the needed 24v that is needed? The Xserver has something closer to the same form factor. The Quick Sliver is more of a box. Both of these have about the same wattage as the mirror door, but does it have the voltages neede?

It was just a quick thought that is all

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MDD's PSU's have a 24pin conn

MDD PSU's have a 24pin connection. Quicksilvers have 22pins. I don't know anything about Xservers. Aren't they pretty flat? Their PSU's must be flat and long?

Voltage comparisons are here:
http://www.outofspec.com/frankenmac/wire.shtml

Check out the other link I provided earlier for more Powermac PSU info:
http://www.applefritter.com/node/23054

Eeun didn't bother providing power to the 28v connection, so evidently it's not needed for the MDD--or at least, not his MDD.