How to test if MDD power supply is bad or it's Something Else

Ok,
I've had a MDD for 4 years. Dec 2007 the PSU died. I had it replaced under my renter's policy (yeah..) the new rev. part was $870!. I Didn't care... insurance paid for the repair.
Now, after 1.5 years, I was having disk corruption issues which led to numerous forced shutdowns (no reset button on the MD) finally, after about 5 of these in one day, the power on light lit when pressed, and I heard a crackle & smelled a a bit of smoke. I pulled the power cord immediately.
btw pressing the power button now did nothing at all, no "fan attempts" no crackle.. nothing.
Same deal, I called the ins co, took MDD to the authorized techs, who checked & said the PSU was dead... again.
The Ins Co. is "totaling" the MDD and I'm looking for a used G5.
BUT! I'd love to get the MDD working again. Just to have it as a second machine.
I've read a bunch of threads here on this issue & testing the PSU.
I'm not a super geek, but I can follow instructions... which I did. There's a great online instruction set with pics and all, about how a guy found a bad solder by disassembling the PSU.
I followed it step by step. Saw nothing remarkable.
Then I came here looking for steps to test the PSU (I'm starting to wonder if it's more than that).
I found a diagram of the pins and voltages.
Connected the PSU the the juice and started testing the connector, where it plugs into the motherboard.
Here's what I found (connected to power but obviously still not starting the computer):
Pin 1 (says +5volts sb, which I assume means stand by?) with the black lead from the tester inserted into pin 2 (gnd). It read 5 Volts.
No other pins showed ANY voltage EXCEPT pin 14 (which says +25Vsb). That read +24.8V when tested.
What I DON'T know is...
If disconnected from the MDD, should all the pins read voltage as the pinout diagram says? I'm brand new to this level of diagnosis.
I'm wondering if maybe the CPU fried etc.
Also, while trying to determine if the power button might be faulty I broke the switch off (duhh). Shorting across the two stubs that were left there didn't produce any powerup either (it's just a 2 pin contact switch right?)
So I need to know if I have accurately found the PSU to be bad. I can get one on ebay for $150-ish.
But I'm worried, since this was a +*new super better PSU*+ and it (possibly) has died, maybe something on the motherboard etc. isn't right.
The machine hasn't been connected to power for 3 weeks & yes, the battery is now dead. I swapped it out, and reconnected the PSU... nothing.
+*So first, did I correctly test the psu?*+
there was a dead link to a MDD repair manual on another thread. First I have to figure out IF the psu is dead, and then decide if something else KILLED it.
Help? I'm using wife's G4 and she's getting real PO'd after 3 weeks!
Thanks to anyone in advance.
Tom

Hi,
Thanks. By power button board, Do you mean the unit that has the power button on it? On the case front?
If so, I mentioned the switch broke while I was testing. I guess to continue I have to get a new switch.
I will pull the mini-board for the power button though to look for signs of damage.
Can I get a new switch to solder on to the board, if the board looks good. The orig. switch physically broke off the board. It's a standard contact switch correct? i.e. press and there should be continuity between the two pins? I'll pull the board as well.
I've already checked the PSU interior. No burnt wires visible anywhere. There's a lot of grey goo glue used so it's hard to see, but since the PSU passed the two passive power tests you mentioned, are we for now assuming it is a good PSU?
Other discussions I've read, describe continuing to test different pins and look for appropriate voltages. That doesn't make sense to me with the computer not starting up.
Aren't the rest of the voltages supposed to show ONLY after the command to supply startup power is given (by the power switch)?
Processor "looks" good too, no signs of burnt anything after pulling the heat sink, but I haven't removed the logic board or the mother board yet to look underneath.

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As an original owner of a G4 MDD DP1.0GHz, AND having MISSED the power supply recall/exchange for the "VERY NOISY" Fan and power-supply combo, I am wondering if this will take me half-way, or all the way to where I would be if I hadn't missed that opportunity?
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Hello, Its been a few years since I posted anything here and I'm getting ready to (possibly) trade in my mirror drive door 1GHZ dual processor machine on one of the current imac-s.
I'm not real hopeful that putting much work into my current machine is worth it. Here's why:
1) crazy levels of noise - I wear woodworking hearing protectors when I surf the web. Listening to music on itunes is fine so long as you like a background of low level blow dryer noise!
2) I'm still running OSX version 10.2.8, I have been too cheap to buy the latest OS. I'm tempted to go out and spend the $119 on 10.5 but I only have the original 256mb of ram installed and since the min requirement of ram is 512, I know I'll need to spend an extra ~50$ on a 512mb PC2700 ram chip. My price tag to do a minimal update is rising...
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In summary, here are my questions.
1) Has anything come along recently to tame MDD G4 fan noise that is easy to install, cost-effective and most of all, something that actually works to decrease the noise?
2) To get the quietest, quickest performance with the current OS 10.5 should I cut my losses now and trade (or sell on ebay) my MDD, sell the new power supply and just purchase a new machine with the OS already installed?
Thanks a bunch in advance for any assistance...
from Bill.

Bill,
Carl has some pretty good points that I'd agree with - trying the replacement PSU and fans should quiet it down somewhat and replacing the stock main fan with a newer, quieter unit will also help. But I'm going to disagree with him on running Leopard on the G4's with a few reservations.
As you might notice from my profile, I'm running Leopard on my dual-867 MDD and find the performance acceptable; perhaps a little slower than Tiger in some respects but it does run well enough within the limitations of the G4's capabilities. The reservation I have about recommending Leopard on a G4 is the graphics card - without Core Image support (which you won't have unless you upgrade the video card) Leopard is going to tax the CPU more and may bog down in some tasks like Quick Look and Cover Flow.
In the end, whether to continue upgrading the G4 is a matter of use and economics. Tiger would be a fine upgrade with minimal cost and squeeze a few more years out of your G4 if you're not requiring software that needs an Intel CPU (like certain iLife '08 apps).
-Douggo

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Hello,
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Hello,
I just bought a used Power Mac G4 (Mirrored Drive Doors) at a garage sale for $20. The owner said it works, but he took out the RAM, power supply unit and hard drive.
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www.otherworldcomputing.com
xlr8yourmac.com
www.lowendmac.com
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http://www.xlr8yourmac.com/systems/g4mirrored_drive_doors/noise_reduction/g4_ddr_noisereduction.html
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I see more Power Supply failure postings here than on any other Older Mac discussion. I think the accommodations made for heat are simply not enough for these hot dual-processor Macs.
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What version is your TC.. A1xxx from the rubber foot?
Power supplies are not available from apple. They do not consider it repairable. It is a sealed consumable.
Power supplies are available from ebay.. simply type time capsule power supply into search.
This is absolutely standard issue that has been ongoing for ages and ages.
See https://sites.google.com/site/lapastenague/a-deconstruction-of-routers-and-modem s/apple-time-capsule-repair
For a multitude of ways to fix it.
The 1 TB drive is LOOSE in there.
No, it is not loose, it has rubber mounts with pins in the bottom base plate. You cannot see the mount points with the base off. This is standard hdd mount for low noise and vibration.
I had thought that the issue was the drive itself was bad.
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Apple Igneous bar

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How to test if MDD power supply is bad or it's Something Else

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