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G4 will not power up

Message #1 - Posted 2004/07/13 - Tom

Hi,

We have a G4 that worked fine one day - next nothing

When you plug the power lead in you hear the little 'zap' of power so we know it has power but pressing the power button on the front does nothing. No clicks, beeps or anything.

Does anyone know how i can de-bug this further? I have a spare G3 that does wprk but the power supply is not rated so high but would it be OK to use this PSU as a test? How do you remove a PSU from a G4 as i'm a PC person

thanks

Message #2 - Posted 2004/07/13 - Gregory Weston

Previously, Tom wrote:

Hi,

We have a G4 that worked fine one day - next nothing

When you plug the power lead in you hear the little 'zap' of power so we know it has power but pressing the power button on the
front does nothing. No clicks, beeps or anything.

Does anyone know how i can de-bug this further? I have a spare G3 that does wprk but the power supply is not rated so high but would
it be OK to use this PSU as a test? How do you remove a PSU from a G4 as i'm a PC person

thanks

How old is the G4 and has it spent any lengthy periods of time unplugged? One of the possible causes of not powering up has historically been a dead PRAM battery. Pressing the power manager reset button has been known to get things sorted out sufficiently to get a boot or two out of it, but won't fix it long term if that's the cause. Unfortunately, I don't have a G4 here to look at and can't remember where that button is - or if it's even consistently placed on the various models - so maybe someone else can give a prod.

IIRC, you'll want to be looking for a round button that's a tad over 1/8" across set in a square assembly that's about 1/4 on a side, or perhaps slightly larger.

Standard output is like your butt. Everyone has one. When using a bathroom, they all default to going into a toilet. However, a person can redirect his "standard output" to somewhere else, if he so chooses. - Jeremy Nixon

Message #3 - Posted 2004/07/13 - Jason

Previously, Tom wrote:

Hi,

We have a G4 that worked fine one day - next nothing

When you plug the power lead in you hear the little 'zap' of power so we

know it has power but pressing the power button on the

front does nothing. No clicks, beeps or anything.

Does anyone know how i can de-bug this further? I have a spare G3 that

does wprk but the power supply is not rated so high but would

it be OK to use this PSU as a test? How do you remove a PSU from a G4 as

i'm a PC person

thanks

Hello,
I agree with the intelligent poster that suggested that you should install a new PRAM battery. If the new PRAM battery does NOT solve your problem, repost and mention in the post that you installed a new PRAM battery.

Don't try making use of a power supply from another computer unless the other computer is identical to the computer that is having the problem. Your idea might work in some cases but may cause major problems in other cases--why take a chance? This advice does not apply to technicians that know about such things as amps, voltage, watts etc.

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Message #4 - Posted 2004/07/13 - Tom

Don't try making use of a power supply from another computer unless the other computer is identical to the computer that is having the problem. Your idea might work in some cases but may cause major problems in other cases--why take a chance? This advice does not apply to technicians that know about such things as amps, voltage, watts etc.

Hi

I have tried it with a different battery and this has not made any difference -

thanks

Message #5 - Posted 2004/07/13 - morenuf

Previously, Jason wrote:

Previously, Tom wrote:

Hi,

We have a G4 that worked fine one day - next nothing

When you plug the power lead in you hear the little 'zap' of power so we

know it has power but pressing the power button on the

front does nothing. No clicks, beeps or anything.

Does anyone know how i can de-bug this further? I have a spare G3 that

does wprk but the power supply is not rated so high but would

it be OK to use this PSU as a test? How do you remove a PSU from a G4 as

i'm a PC person

thanks

Hello,
I agree with the intelligent poster that suggested that you should install a new PRAM battery. If the new PRAM battery does NOT solve your problem, repost and mention in the post that you installed a new PRAM battery.

I gather you've tried replacing the PRAM battery with no luck.

While it could indeed be hardware (motherboard, powersupply, or bad RAM even a monitor,etc and once you have eliminated these) it is worth it to try the following:

Disconnect ALL external addons (USB & Firewire SCSI hard drives scanners DVDs CD burners, USB & firewire hubs, etc). While keyboard & mouse are not likely candidates here, but if you have others try them later too.

Open Mac case (with power off but power cord still plugged in).

Once case is open, touch the power supply case to remove any stray static electricity charge your body may have before touching any other internal components.

If you have added RAM, remove the newer added RAM.

It would not hurt to make sure all internal cable connections are good, by removing & reseating all such cables, especially those which connect to the motherboard.

ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ You may have already done this PRAM battery replacement

Replace the PRAM battery on the motherboard. This is a 3.6 volt lithium battery readily available at computer supply stores. A dead PRAM battery can prevent boot up or video on monitor. ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ Near the battery on the motherboard is a PMU (Power Manager Unit -- on older Macs this was called CUDA hardware reset button) button. Press this ONCE (too many presses might leave PMU in unhappy state and can drain a new PRAM battery with hours rather than 3-5 years). Some may refer to this as a hardware rest button but PMU is Apple nomenclature.

On start up reset PRAM by pressing Command Option P & R keys simultaneously. I think you need to hold these buttons down until Mac chimes 3 times. This PRAM reset is likely already down by the PMU reset but do it anyway.

Hopefully your Mac will boot successfully after all this. I had this problem occur several times (about 3-4 times total with the two G4s) with both a G4 450 and a G4 933. Most times this happened after power outages when G4 was on. Once it happened after I had case open replacing hard disks, and once when thunderstorms occurred. I suspect small static charges or voltage spikes may have affected the sensitive PMU.

One G4 actually had some minor corrosion on PRAM battery contacts on the motherboard which I cleaned.

Good luck. I hope this works for you. The first time it happened to me took several weeks of grief to correct it. But it did work for me. Morenuf

morenuf@nobodyhome.com.invalid
--
morenuf@nobodyhome.com.invalid

Message #6 - Posted 2004/07/13 - RDot

"Tom" <tomNOSPAM@teameazyriders.com> wrote in message news:<1089711153.18345.0@spandrell.news.uk.clara.net>...

Hi,

We have a G4 that worked fine one day - next nothing

When you plug the power lead in you hear the little 'zap' of power so we know it has power but pressing the power button on the front does nothing. No clicks, beeps or anything.

Does anyone know how i can de-bug this further? I have a spare G3 that does wprk but the power supply is not rated so high but would it be OK to use this PSU as a test? How do you remove a PSU from a G4 as i'm a PC person

thanks

Try unplugging the G4 from the wall socket. Wait 10 minutes. Re-plug the wall socket and hit the power button.

If that doesns't work, Open the side of the g4 and find the pmu switch on the logic board. Unplug the power again.

ONLY ONCE, Press the pmu button (it is small black button near the processor) If you press the pmu more than once during a cycle, it may cause permanent damage to the logic board. wait one minute, power the computer back up.

Message #7 - Posted 2004/07/14 - G.T.

RDot wrote:

"Tom" <tomNOSPAM@teameazyriders.com> wrote in message news:<1089711153.18345.0@spandrell.news.uk.clara.net>...

Hi,

We have a G4 that worked fine one day - next nothing

When you plug the power lead in you hear the little 'zap' of power so we know it has power but pressing the power button on the front does nothing. No clicks, beeps or anything.

Does anyone know how i can de-bug this further? I have a spare G3 that does wprk but the power supply is not rated so high but would it be OK to use this PSU as a test? How do you remove a PSU from a G4 as i'm a PC person

thanks

Try unplugging the G4 from the wall socket. Wait 10 minutes. Re-plug the wall socket and hit the power button.

If that doesns't work, Open the side of the g4 and find the pmu switch on the logic board. Unplug the power again.

ONLY ONCE, Press the pmu button (it is small black button near the processor) If you press the pmu more than once during a cycle, it may cause permanent damage to the logic board. wait one minute, power the computer back up.

I had 2 power supplies go bad in a Quicksilver 2002. Tried all the above but unfortunately there was nothing to do but get a new PS both times. And I had the shop do it because it didn't look as simple as changing a PC power supply. I haven't looked that closely at my G5 at work but it would nice if Apple would start designing for more user replaceable parts, toolless would be preferred. The Dells at work are a pleasure to work on because of their ease of repair.

Greg

Destroy your safe and happy lives
Before it is too late
The battles we fought were long and hard
Just not to be consumed by rock'n'roll

Message #8 - Posted 2004/07/17 - Manny Pinsky

I'm having the same problem with my G4/1g/mdd/512/60.
At one time I thought it was some badly seated RAM but this proved not the case. I upgraded to 512 and this did nothing. It was not suppose to , but....
This does not happen on a daily or weekly basis, but does occur.

Anybody have a suggestion.

my Battery voltage is 3.6v.

Previously, RDot wrote:

"Tom" <tomNOSPAM@teameazyriders.com> wrote in message news:<1089711153.18345.0@spandrell.news.uk.clara.net>...

Hi,

We have a G4 that worked fine one day - next nothing

When you plug the power lead in you hear the little 'zap' of power so we know it has power but pressing the power button on the
front does nothing. No clicks, beeps or anything.

Does anyone know how i can de-bug this further? I have a spare G3 that does wprk but the power supply is not rated so high but would
it be OK to use this PSU as a test? How do you remove a PSU from a G4 as i'm a PC person

thanks

Try unplugging the G4 from the wall socket. Wait 10 minutes. Re-plug the wall socket and hit the power button.

If that doesns't work, Open the side of the g4 and find the pmu switch on the logic board. Unplug the power again.

ONLY ONCE, Press the pmu button (it is small black button near the processor) If you press the pmu more than once during a cycle, it may cause permanent damage to the logic board. wait one minute, power the computer back up.

--

Remove "Nospam" for the correct address.

Message #9 - Posted 2004/07/17 - Jason

Previously, Manny Pinsky wrote:

I'm having the same problem with my G4/1g/mdd/512/60. At one time I thought it was some badly seated RAM but this proved not the case. I upgraded to 512 and this did nothing. It was not suppose to , but....
This does not happen on a daily or weekly basis, but does occur.

Anybody have a suggestion.

my Battery voltage is 3.6v.

The first step is to change out the PRAM battery.

The next step is to make sure it is plugged into a working outlet.

I agree with the person that told you to unplug it for ten minutes and after that--plugging it back in.

There could be a problem with the power supply.

You need to repost and tell us whether or not you can hear the hard drive spinning up after pushing the power switch. Also tell us whether or not it could be a monitor problem.

It's possible the hard drive is defective. One way to check whether or not it is the internal drive. If your mac does not start up--install a CD that has a system file such as almost any Apple made CD such as the OS 9 CD. A Norton's Utility CD should also work. Hold down the C key. If your computer starts from the CD but does not start when the CD is removed--it's usually an indication that the internal hard drive has died.

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