Apple Event: May 7th at 7 am PT

Looks like no one’s replied in a while. To start the conversation again, simply ask a new question.

Level 1

4 points

My MDD G4 won't start using power button

I'm using a MDD G4 Dual 867 Mhz for running older software, and I can't get the unit to start using the power button. Sometimes the button lights up when pressed and sometimes it doesn't but it won't start up unless I have used it that day or the day before and then it will start. Up until now, if I unplug the power cord or open the case and press the PMU button on the logic board, the computer will start using the button. I would like to find out why the unit is doing this so I can possibly repair it, as I want to continue to use it for my older software....Thanks.

Mirror Door G4

Posted on Oct 24, 2012 5:03 PM

30 replies

japamac

Level 7

24,400 points

Nov 1, 2012 2:46 PM in response to NoelK99

You shouldn't use the PMU button for starting and stopping the machine. You will crash the PMU and then you will need a new logic board.

PMU resets should only be performed as outlined in the article that I previously linked.

Resetting PMU on Power Mac G5, Power Mac G4 ... - Support - Apple

NoelK99 Author

Level 1

4 points

Nov 2, 2012 3:23 PM in response to japamac

Well, I did all this and I still can't start the computer with the power button. It must be another issue. It still will only start with the button if I unplug the power cord, plug it back in and then it will start with the button. The exact same symptoms as I started with, so I can only assume it wasn't the battery.

BDAqua

Level 10

239,363 points

Nov 2, 2012 4:55 PM in response to NoelK99

Sounds like a bad capacitor, normally in the PSU.

NoelK99 Author

Level 1

4 points

Nov 3, 2012 11:35 AM in response to BDAqua

What can be done to fix this, if anything? Will it be an expensive repair?

BDAqua

Level 10

239,363 points

Nov 3, 2012 2:36 PM in response to NoelK99

Probably not easy to fix, find a replacement PSU, or...

You can convert an ATX PSU for use on a G4...

http://atxg4.com/sawtooth.html http://atxg4.com/gige-da.html

http://atxg4.com/quicksilver.html

http://atxg4.com/mdd.html

http://atxg4.com/

NoelK99 Author

Level 1

4 points

Nov 3, 2012 3:19 PM in response to BDAqua

This option is not really acceptable. I can do some soldering, but I'm no Apple tech, and besides that there are too many variables in the results with functions not working etc.

There are some power supply units for sale on Ebay. Are you fairly certain that I can fix this with a replacement power supply? Also, there are some power units that are 360 watts, and some of them are 400 watts. Do you know which one would be suitable for my machine? Dual Processor 867 MHz.

BDAqua

Level 10

239,363 points

Nov 3, 2012 3:38 PM in response to NoelK99

Are you fairly certain that I can fix this with a replacement power supply?

Only fairly certain, not positive.

Also, there are some power units that are 360 watts, and some of them are 400 watts. Do you know which one would be suitable for my machine? Dual Processor 867 MHz.

Either one, the 360 watt one was a replacement for the original 400 watt one that got many noise complaints.

Jacumba

Level 4

2,349 points

Nov 5, 2012 3:36 PM in response to NoelK99

Several days ago when I was last here I assumed you got the computer going. I would check the receptacle that the power cord plugs into, it could be faulty, or worn? Whether it's a wall outlet or a control strip your plugging into.

It doesn't seem like a power supply? In the past when I've seen them go, they're dead, and not just working once in awhile.

The more watts the better incase you want to run dual monitors, etc. The last power supply I bought was from

http://www.cputopia.com/ very good service, I replaced a 300 watt with a 480 watt. It was only $19 so they are cheap. If you scroll to the bottom and click on Mac Repair. You can contact them to see if they have one for your computer.

NoelK99 Author

Level 1

4 points

Nov 8, 2012 10:44 AM in response to Jacumba

I don't think there is a power cord issue. The symptoms are pretty consistant. I push power button to start...the button is ineffective...I reach in back of the CPU, pull the power plug out and push back in...press power button again, unit starts up. Always same response.

Is it possible that the power button unit is defective? is there an integrated circuit board or other component attached to the button that would cause this problem?

I will check the URL you posted and see what they have...thanks for the info.

Edit to add: I just checked the CPUTOPIA site, and the only Apple stuff they have is some Macbook keyboards. There are some power supply units for the MDD unit and a power button module on ebay, if they are still available.

Jacumba

Level 4

2,349 points

Nov 9, 2012 12:01 PM in response to NoelK99

Noel, I really don't know I've never had a problem with a power button or replaced one. Other than an old Mac that if you press the button it got lodged sideways and stuck in, so you have to be very delicate when you press it. It's certainly some odd symptoms that your having. Maybe you can search the internet or someone may come in here with some knowledge of the computer problem. Post back if you come up with anything.

NoelK99 Author

Level 1

4 points

Nov 9, 2012 3:29 PM in response to Jacumba

OK, thanks for trying. I might just buy a refurbushed MDD 1.25 GHz model. This one is slow and having one that is a bit faster would be nice. It's just too bad I have to spend over $400 to get one.

Nov 13, 2012 6:35 AM in response to NoelK99

Try dvwarehouse.com. They have a dual 1.25 on sale now for $199. Of course, there's shipping, but I've gotten two computers from them, and they're a good place to deal with. The computers are refurbed; only thing is you don't get system disks with them.

NoelK99 Author

Level 1

4 points

Nov 13, 2012 7:37 AM in response to Boscobrains

Thanks for the suggestion. The units they have listed there are lower priced than what I have seen on other used Mac sites I have dealt with before. I will probably give them a try.

Jacumba

Level 4

2,349 points

Nov 13, 2012 9:51 AM in response to NoelK99

The following was taking off craigslist it also includes a 20" monitor.

Model: Power Mac G5

CPU Type: PowerPC G5

Number of CPUs: 2

CPU Speed: 2 GHz

Memory: 4 GB

Pioneer DVD/CD write/read drive

Let me know if you have any questions or would like to see additional photos.

$125 Cash takes it!

So also check out craigslist in your area and keep looking. I see these all the time there. BTW I wouldn't take a computer with a 1.25 GHz cpu if it was for free.

NoelK99 Author

Level 1

4 points

Nov 13, 2012 10:13 AM in response to Jacumba

<QUOTE>: "The following was taking off craigslist it also includes a 20" monitor.

Model: Power Mac G5, CPU Type: PowerPC G5, Number of CPUs: 2, CPU Speed: 2 GHz, Memory: 4 GB

Pioneer DVD/CD write/read drive, Let me know if you have any questions or would like to see additional photos.

$125 Cash takes it!

So also check out craigslist in your area and keep looking. I see these all the time there.

BTW I wouldn't take a computer with a 1.25 GHz cpu if it was for free." </QUOTE>

Why not?

I have a G5 1.8 GHz model in addition to the MDD 867 Dual I already have. I need an MDD with dual boot, so I can run OS 9 software, and OSX as well.

My MDD G4 won't start using power button