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PowerMac G4 MDD won't power up

L

leahkat

macrumors member
Original poster
Feb 27, 2012
30
0
I've got a PowerMac G4 MDD (1.25GHz) (2003), which has been running 10.5.8. I shut it down recently (I rarely do this) and it wouldn't power on again. No power light. Nothing at all. I unplugged the power cord for a few minutes and then re-connected. After that it powered up again fine. Shut it down again a day later to see if the issue had been resolved and again, I had to unplug power, wait and replug to get it to start up. This time clock was reset. Alas I don't know much about computers... What needs to be replaced? or is it finally on it's last leg?

Any help? Thanks in advance.
 
leahkat said:
I've got a PowerMac G4 MDD (1.25GHz) (2003), which has been running 10.5.8. I shut it down recently (I rarely do this) and it wouldn't power on again. No power light. Nothing at all. I unplugged the power cord for a few minutes and then re-connected. After that it powered up again fine. Shut it down again a day later to see if the issue had been resolved and again, I had to unplug power, wait and replug to get it to start up. This time clock was reset. Alas I don't know much about computers... What needs to be replaced? or is it finally on it's last leg?

Any help? Thanks in advance.
Click to expand...

Probably power supply. That's what failed on my MDD. A new PSU can be had for fairly cheap, but the computer isn't worth a ton. You can check the pinout of the PSU to make sure it is dead, the pin diagram should be online somewhere. Good luck!
 
Macman756 said:
Probably power supply. That's what failed on my MDD. A new PSU can be had for fairly cheap, but the computer isn't worth a ton. You can check the pinout of the PSU to make sure it is dead, the pin diagram should be online somewhere. Good luck!
Click to expand...

Thanks. I'll look for the diagram and PSU prices.
I have come across advice for resetting PMU and replacing PRAM battery also... Should I try all of these? Any advice on the order? Thanks again!
 
The same thing happened to me. The power supply eventually sounded like it was shorting out, and it started interfering with the other electrical sockets in the room. I decided to stop using it instead of risking a blowout. Blame Foxconn in China.
 
In my extensive experience with MDD PowerMacs, I can tell you that I'm 100% certain that your power supply is on its way out.

Check out my blog (below) on MDD's.
 
leahkat said:
I've got a PowerMac G4 MDD (1.25GHz) (2003), which has been running 10.5.8. I shut it down recently (I rarely do this) and it wouldn't power on again. No power light. Nothing at all. I unplugged the power cord for a few minutes and then re-connected. After that it powered up again fine. Shut it down again a day later to see if the issue had been resolved and again, I had to unplug power, wait and replug to get it to start up. This time clock was reset. Alas I don't know much about computers... What needs to be replaced? or is it finally on it's last leg?

Any help? Thanks in advance.
Click to expand...

try new battery on motherboard cheapest first step
 
This happens to me with my MDD on occasion. (Same model as OP's as a matter of fact) What specifically causes the power supply to do this? I'm an electrical engineer and from my standpoint it doesn’t make any sense that the power button would do absolutely nothing, nor does the fact that unplugging/replugging the power cord fixes the problem temporarily make any sense either.
 
It's the power supply, we have a dual 867 that had it power supply replaced after the same circumstances you described. Can't hurt to change out the battery, it's cheap. The power supply will cost more than the computer is worth. It might be time to upgrade, just a suggestion.
Here are some links to look at.
- http://www.macpalace.com/mac-parts/p/661-2816-powermac-g4-mdd-power-supply-614-0224/
- http://www.dvwarehouse.com/Power-Supply-360W-for-Power-Mac-G4-Mirror-Door--(867Mhz-1GHz-1.2ghz-1.4Ghz)-661-2816---614-0224-p-35457.html
As you can see they aren't cheap.
 
kpgh554 said:
try new battery on motherboard cheapest first step
Click to expand...

It sounds like the motherboard is not getting any power from the CPU after a normal shutdown. This situation will drain a new battery very quickly.

However, if the "unplug-plugin ritual" is done just after shutdown instead of waiting for the next restart, you can save on battery use and still have the fresh battery there to hold clock & settings during those few seconds.

Here is the PSU pin-out and diagnostic instructions:

http://www.jcsenterprises.com/Japamacs_Page/Blog/D275729F-09DA-4FBB-96B3-BEEEB2C04619.html

I'd perform the test both ways. First try it after a normal shutdown. Failure?

Now try it after the unplugging it for a second. Pass?

If this is the case, then yes, get a new PRAM battery and get by with doing it this way until you plan your next step (Unplug and replug immediately after shutdown instead of waiting for next start-up). If you're okay with doing it this way, it may last a while longer yet. I'm not sure. If not, you might consider an ATX conversion (if you're not using ADC) or a rebuilt PSU.

iDecker said:
In my extensive experience with MDD PowerMacs, I can tell you that I'm 100% certain that your power supply is on its way out.
Click to expand...

I agree that this is a PSU issue, but I'm not 100% sure that it means that it's on its way out. Likely, this is the result of a component on the PSU board that has already failed. That doesn't necessarily mean that it will lead to, or is a precursor of, additional failures. Or maybe you have more information that I do? Looking at your blog, it appears that you've worked on these a bit. Have you isolated the exact cause for this? I need to get my hands on one of these PSUs.
 
From what I understand, there is a particular component that is to blame along with the often-assumed capacitors.

I'm assuming, as my knowledge of electronic components is limited, that the failure of the capacitors will lead to the failure of another particular component, I forget which. Either way, even when the PSU is plugged in with the Mac powered off, something is drawing power and it eventually burns out the aforementioned component. Supposedly, when the PSU is plugged in and the Mac is off, it feels hotter than when the Mac is on. :confused:

Try starting with the PRAM battery removed?

I just replace the PSU standard ATX PSU.
 
iDecker said:
Supposedly, when the PSU is plugged in and the Mac is off, it feels hotter than when the Mac is on. :confused:
Click to expand...

Maybe we're not talking about the same thing? All reports of this that I've seen (I even had my hands on one for a short time, but didn't get a chance to tear it down) indicate that the PSU is, for all intents and purposes, dead after a normal shutdown. It's cold and does not provide the normal standby power to the motherboard, thereby draining the battery. However, unplugging it for only a second will return it to normal and provide standby power until the next restart. Is that not what we're dealing with here?
 
All that I'm going on is what I heard, and that is that the PSU is drawing more power than it should when it is plugged in and shut down. Sounds related, to me. Consuming power but not supplying it to the mother board while it's off :confused: may be storing power and thus burning up.
 
iDecker said:
All that I'm going on is what I heard, and that is that the PSU is drawing more power than it should when it is plugged in and shut down. Sounds related, to me. Consuming power but not supplying it to the mother board while it's off :confused: may be storing power and thus burning up.
Click to expand...

Yeah, we're talking about two different things then.

OP, do you have an in-line amp meter to measure what is going from your wall socket to the computer after a normal shutdown? Or maybe a friend who has one?
 
It seems to me that if the power supply is not providing standby power to the motherboard after shutdown then the 20-pin (?) ATX connector that supplies power to the motherboard will read 0 volts on all the pins with a voltmeter. You could do this by leaving the MDD plugged in after a power button push failed to turn it on, opening the case, unplugging the power connector to the motherboard and testing all the pins on the power connector. (Yes, in theory some of the wires should be hot. I wouldn't recommend this if you don't know how to use a multimeter.)

If none of the pins are hot then the powersupply is not providing standby power to the motherboard, and you've chased down your little problem. Simple as that. (Unless I'm missing something?)
 
ThunderSnake said:
It sounds like the motherboard is not getting any power from the CPU after a normal shutdown. This situation will drain a new battery very quickly.

However, if the "unplug-plugin ritual" is done just after shutdown instead of waiting for the next restart, you can save on battery use and still have the fresh battery there to hold clock & settings during those few seconds.

Here is the PSU pin-out and diagnostic instructions:

http://www.jcsenterprises.com/Japamacs_Page/Blog/D275729F-09DA-4FBB-96B3-BEEEB2C04619.html

I'd perform the test both ways. First try it after a normal shutdown. Failure?

Now try it after the unplugging it for a second. Pass?

If this is the case, then yes, get a new PRAM battery and get by with doing it this way until you plan your next step (Unplug and replug immediately after shutdown instead of waiting for next start-up). If you're okay with doing it this way, it may last a while longer yet. I'm not sure. If not, you might consider an ATX conversion (if you're not using ADC) or a rebuilt PSU.



I agree that this is a PSU issue, but I'm not 100% sure that it means that it's on its way out. Likely, this is the result of a component on the PSU board that has already failed. That doesn't necessarily mean that it will lead to, or is a precursor of, additional failures. Or maybe you have more information that I do? Looking at your blog, it appears that you've worked on these a bit. Have you isolated the exact cause for this? I need to get my hands on one of these PSUs.
Click to expand...

Thanks for the pin-out link. It was exactly as you say... test after normal shutdown=fail, test after unplugging/replugging=pass. I suppose I will be looking for another PSU! (Dane D.- I know the computer isn't 'worth' much, but right now it's worth lots to me as I'm not prepared to upgrade just yet! ;) ... and thanks for the replacement psu links!)

----------
ThunderSnake said:
Yeah, we're talking about two different things then.

OP, do you have an in-line amp meter to measure what is going from your wall socket to the computer after a normal shutdown? Or maybe a friend who has one?
Click to expand...

We metered the output voltage of the power supply and it had no output after initial shutdown. After unplug/replug voltage came back up.
 
Forget all of that nonsense.

If you don't use the Apple Display Connector, buy one of these Mini ITX PSU's and follow my guide here.

Cut the cable off both power supplies. Cut the new one close to the Molex connector and the old one close to the PSU. Splice the matching wire colors (check the voltages first, just in case) and plug it right back in and you have a working Mac!

Now velcro, bolt, or find another way to just stuff the tiny PSU in the place of the old behemoth.

That's less than $60 and one-day of work. No waiting for shipping it back and forth and such and it will run quieter!
 
leahkat said:
Considering this repair option...
http://natramelec.com/g4index.htm?gclid=CL7P0d2Gwq4CFQSR7Qod3070WA
Click to expand...

Here's another option:
http://www.ebay.com/itm/33065343694...:IT&_trksid=p3984.m1438.l2648#ht_10998wt_1042

The asking price is high, but they accepted my best offer of $80. That puts the cost just under $100 with the shipping, and includes the new CPU fan. I thought it was a good deal. The installation is easy and my FW800 is much quieter and runs very much cooler. It will startup and shutdown on its own now. Before, I could only schedule a shutdown, and sometimes that wouldn't work. But it would never startup on a schedule. Now it does.

Of course, this is the exact same 360 watt power supply that I replaced, so I'm sure it will eventually start to fail, as well. But this machine will be retired many years before that.

For what it's worth, for nearly the last two years I have been shutting down by holding the power button in for 5 seconds--a forced shutdown. I found the computer will always start up from the button the next time. I suppose it is the same as unplugging it, but you don't have to reach around the back of the computer to do it. I would have kept doing this except the fans were getting increasingly noisy. Nice and quiet now.

iDecker's suggestion is a good way to go. I was ready to do go that route until I saw the above auction.

Anyway, this is my experience. Good luck to you.
 
archtopshop said:
Here's another option:
http://www.ebay.com/itm/33065343694...:IT&_trksid=p3984.m1438.l2648#ht_10998wt_1042

The asking price is high, but they accepted my best offer of $80. That puts the cost just under $100 with the shipping, and includes the new CPU fan. I thought it was a good deal. The installation is easy and my FW800 is much quieter and runs very much cooler. It will startup and shutdown on its own now. Before, I could only schedule a shutdown, and sometimes that wouldn't work. But it would never startup on a schedule. Now it does.

Of course, this is the exact same 360 watt power supply that I replaced, so I'm sure it will eventually start to fail, as well. But this machine will be retired many years before that.

For what it's worth, for nearly the last two years I have been shutting down by holding the power button in for 5 seconds--a forced shutdown. I found the computer will always start up from the button the next time. I suppose it is the same as unplugging it, but you don't have to reach around the back of the computer to do it. I would have kept doing this except the fans were getting increasingly noisy. Nice and quiet now.

iDecker's suggestion is a good way to go. I was ready to do go that route until I saw the above auction.

Anyway, this is my experience. Good luck to you.
Click to expand...

This one will work in my 2003 MDD?
 
That. Costs. Too. Much! Wow... I'd buy a whole new Mac for that price. Hello PowerBook!
 
No no, they're asking price. $199 for such out-dated hardware? That would be like replacing a Macintosh with a Macintosh, just upgrade.

Although... I'd like to get my Macintosh running =\
 
archtopshop said:
Really? I thought $80 plus shipping was a good price for a new power supply and CPU fan.
Click to expand...

It is. That's quite a good deal for that package. It's unused and it also comes with the quieter main fan. I don't even need a PSU at the moment and I'm thinking of offering the $80 that you did (there are 7 available, so don't worry, OP).

Thanks for the tip on that.

----------

leahkat, let me know what you're planning to do here. If you want this, I'm going to wait for you to make your offer first, so they don't feel that they're getting too many low-ball offers at once.
 
Your welcome. Last time I looked, mine was the only offer. Hopefully, everyone who wants one will get one at that price.
 
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