My MDD G4 won't start using power button

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

Reply

Answer 1

Oct 24, 2012 6:02 PM in response to NoelK99

Your internal PRAM battery may be weak or discharged. Suggest you replace the battery. Check this site for battery part numbers and sources. https://sites.google.com/site/macpram/mac-pram-nvram-cuda-pmu-battery-tutorialMac PRAM, NVRAM, CUDA/PMU & Battery Tutorial

 Cheers, Tom 😉

Reply

Answer 2

NoelK99 Author

Level 1

4 points

Oct 25, 2012 4:52 AM in response to Texas Mac Man

Thank you. I will try this and report the results.

Reply

Answer 3

NoelK99 Author

Level 1

4 points

Oct 30, 2012 2:05 PM in response to Texas Mac Man

I replaced the battery and still have same problem. Any other suggestions?

Reply

Answer 4

japamac

Level 7

24,400 points

Oct 30, 2012 5:55 PM in response to NoelK99

Does the MDD have an ADC port equipped graphics card installed?

It is possible for an ADC card (due to fault) to interfere with the power functions of the machine.

Trying a non-ADC port equipped card could test this.

You may wish to test the PSU to verify that trickle voltage is present when the no start condition occurs:

D275729F-09DA-4FBB-96B3-BEEEB2C04619.html

Reply

Answer 5

NoelK99 Author

Level 1

4 points

Oct 31, 2012 6:39 AM in response to japamac

I have a standard apple graphics card. The problem has developed over the last month or 6 weeks, without any additions of new hardware. I will have to get a new multi-meter if I'm going to go through the electrical routine, and if that is not the problem, it might be a power button thing. I'm getting frustrated with this. Maybe I would be better off just getting another MDD G4 that is refurbed, but will cost a lot more to do that. I need Dual Boot, so I'll have to get one that is no faster than 1.25 GHz, am I right?

Reply

Answer 6

japamac

Level 7

24,400 points

Oct 31, 2012 6:55 AM in response to NoelK99

The PSU test is a good idea before throwing money at parts (like the power button board).

Standard graphics cards usually included a card with an ADC port.

Dual boot capable MDDs were all original models and the 2003 MDD. The FW 800 models were not capable of booting OS 9.

So, Yes, no faster than 1.25 GHz.

http://www.everymac.com/systems/apple/powermac_g4/index-powermac-g4.html

Reply

Answer 7

NoelK99 Author

Level 1

4 points

Oct 31, 2012 8:59 AM in response to japamac

Are you saying that some problem could have developed on its own with the video card, although I have not made any changes or additions to it? I don't have another video card laying around to test with. My monitor is an old-style RGB CRT, and I am sharing it with a PCI-X 1.8 GHz G5 hooked up to it with my G4 using a KVM switch.

If I do the voltage test using a multi-meter and find no faults with it, what should I do next. I would like to save money by just replacing parts if I can, but I would spend the money on an upgraded 1.25 MHz MDD so I can still use my old software. Buying updated software would be much more expensive than replacing the computer, and I still have uses for a few programs thast run on OS9.

Thanks for info so far.

Reply

Answer 8

Jacumba

Level 4

2,349 points

Oct 31, 2012 1:09 PM in response to NoelK99

Video cards do go bad but it's unlikely that it would cause the computer not to start. You would have had prior symptoms of poor video or the computer restarting over and over on it's own.

There's a good chance the pram battery was bad, that lead to this, which you've replaced. So now that you've replaced the pram battery. Try pressing the cuda button on the motherboard. This should fire up the cooling and power supply fans. If so the computer may boot to the OS? If not the ram may have become corruped.

So pull all the ram out of the computer and start it, you'll hear one beep. Then shut down the computer. Now insert one ram stick only and start the computer, it should start. Now turn off the computer and repeat this process installing one ram stick at a time and turning off the computer till you have them all back in place.

Reply

Answer 9

NoelK99 Author

Level 1

4 points

Oct 31, 2012 3:25 PM in response to Jacumba

Sorry, I don't know what the "cuda" button is. Could you describe where that is on the motherboard?

Thanks.

Reply

Answer 10

japamac

Level 7

24,400 points

Oct 31, 2012 3:52 PM in response to NoelK99

Cuda=PMU

Reply

Answer 11

Jacumba

Level 4

2,349 points

Oct 31, 2012 3:53 PM in response to NoelK99

I'm not sure where it is on the G4 motherboard? On the G3 I have. There are two small buttons just below the pram battery. The one closest to the battery is the cuda. Perhaps there is a motherboard layout online for your model Mac.

Also if your not use to working inside the computer case please unplug the power source and be careful of creating static electricity while touching anything in the computer, could damage it. You can do this by wearing a wrist band ground or touching metal before putting your hand inside the case. Carpet flooring can cause static electricity.

Reply

Answer 12

japamac

Level 7

24,400 points

Oct 31, 2012 3:56 PM in response to Jacumba

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

Reply

Answer 13

NoelK99 Author

Level 1

4 points

Oct 31, 2012 4:15 PM in response to japamac

OK, I know the PMU button...thanks.

Reply

Answer 14

Jacumba

Level 4

2,349 points

Oct 31, 2012 4:48 PM in response to NoelK99

Good job lol

Reply

Answer 15

NoelK99 Author

Level 1

4 points

Nov 1, 2012 11:24 AM in response to Jacumba

I followed your directions. The only thing is pressing the PMU button did not make the unit start up, so I used the regular power button on the case to start it. After that however, I was able to shut it down using the PMU button. So then I removed the RAM modules, started using power button, and it made the beep noise as you said. Then shutting down using PMU button, starting with power button and adding RAM modules one stick at a time, all went well.

Funny thing is, I was able to start using the power button on the first try without unplugging the power cord, so maybe the unit is working propertly now. If it starts up with the power button tomorrow, I will assume the unit is OK for now, otherwise I will report the results tomorrow. Thanks to everyone who had some tips on the problem.

Reply