Power on problem/half AA battery

Tinpusher

Tinpusher

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I have a job that means leaving home for, sometimes, up to 3 weeks at a time.

Sometimes when I have returned from a trip, my G4's internal clock has reset to 1/1/1901 (or whatever). I put this down to a flat internal battery and resolved to replace it at some point, but never got around to it.

Recently, I came back from a 3 week trip and tried to power on the G4. And: northing. Absolutely zip, nada, Foxtrot Alpha. The light behind the power on switch doesn't even illuminate when I press the button (I've had a similar problem before, where the G4 didn't power on but the light illuminated when the button was pushed. This problem was solved by replacing the half AA battery inside).

So, reading the past threads on this forum I resolve to get a new half AA battery, push the PRAM button next to the battery holder and hope for the best.

Questions are:

1. Will this work do we think?

2. Can I get a rechargable half AA battery? It looks like the only ones available are non-rechargables.

Many thanks in advance, folks.
 
1. Maybe - You can try that. Try pushing the PRAM reset button first. Usually, if you get no response at all, the problem will be fixed by replacing the power supply.

2. I have never seen a rechargeable PRAM battery. I don't know if they exist, or not. And, there's no provision in your Mac for charging a battery like that. The batteries usually last for several years, so there's little demand for a rechargeable, I think.
 
If the time keeps resetting itself when the Mac is off, it's usually because of a drained-out PRAM battery. Places like Radio Shack sell them, but I'm not sure of the cost. You can also search on WeLoveMacs.com or other Mac retailers.
 
OK, replaced the PRAM battery (which was probably due anyway), but... nothing.

The most obvious thing is the fuse in the plug, which is fine. The power cord is fine. Everything's plugged in correctly, but still when I press the power button, absolutely nothing happens.

Is there an internal fuse that might have gone? I can't see one when I open the machine up.
 
After you installed the battery, did you push the PMU button near the battery? Only push it once quickly. Pushing it too many times can crash the PMU, causing the life of the PRAM battery to be significantly shortened. The information you need is available here:
http://support.apple.com/kb/HT1939
 
Sometimes if the time is way off, you need to set it manually. Once it's set approximately to the correct time, it should be able to sync with NTP servers on the Internet. It should hold it then.

Also, make sure you put the battery in correctly. ;)
 
Hmmm. Battery is in correctly. Instructions followed from the Apple KB article (thank you for the link, nixgeek).

Apart from pushing the PMU reset button twice (once with the battery out, once with the battery in), I did everything as per the KB article.

However, still nothing. Are we getting into the realms of "take it to Apple servicing"?
 
Interesting. It would appear that Apple's KB article advocates unplugging everything; Headgap (as I read it) advocate pushing the cuda button with the power supply plugged in.

At any rate, neither worked so I'm down to a total discharge of the machine. One question on this, though- Headgap says that if it doesn't work, "pull the RAM". Does this mean remove the RAM chips?
 
Tinpusher said:
At any rate, neither worked so I'm down to a total discharge of the machine. One question on this, though- Headgap says that if it doesn't work, "pull the RAM". Does this mean remove the RAM chips?
Click to expand...

I believe it does. Pull all of your RAM and then try what they say. See if this works for you.
 
OK, well I'm off on a trip with work for a week or so.

I've unplugged everything, taken the battery out and will remove the RAM when I get back. Then try and fire it up again... fingers crossed!

Nixgeek, thank you very much for your advice this evening. I will resurrect this thread when I return from my monster-trip to Seville, Cuidad Real, Barcelona and Hannover!
 
Tinpusher said:
OK, well I'm off on a trip with work for a week or so.

I've unplugged everything, taken the battery out and will remove the RAM when I get back. Then try and fire it up again... fingers crossed!

Nixgeek, thank you very much for your advice this evening. I will resurrect this thread when I return from my monster-trip to Seville, Cuidad Real, Barcelona and Hannover!
Click to expand...

Sounds good...looking forward to it. Make sure that when you do put everything back together that you leave it plugged in for a while without rebooting. Then, try and reboot and see if it keeps the time.

Good luck. :)
 
Right, even after following Headgap's instructions to the letter, the power on is still not happening.

So I'm going for a total discharge. I've unplugged everything, taken the battery out, pushed the CUDA switch (6 seconds) then the power switch (6 seconds) and I'm leaving the computer in this state whilst I'm away from home for a week or so.

If this doesn't work, then I think I'm definately going to have to start replacing parts.

What could have caused this in the first place? I don't want it to happen again.
 
So are you still having problem with the Mac turning on at all, or is it just the time discrepancy? I'm a little confused now...I thought you solved the power problem.
 
No, the problem is with the computer not turning on at all. There would appear to be no power whatsoever going to the machine.
 
Apple's service manual would take you to the logic board power supply plug to check for power with a meter. Your symptoms will normally result in a dead power supply as the culprit. And, the fix is replacing the power supply. I think you have mostly eliminated other major causes.
 
DeltaMac said:
Apple's service manual would take you to the logic board power supply plug to check for power with a meter. Your symptoms will normally result in a dead power supply as the culprit. And, the fix is replacing the power supply. I think you have mostly eliminated other major causes.
Click to expand...

You beat me to the punch. :p

I've heard on another forum that the Quicksilver G4 Power Macs have recently suffered from power supplies failing, so I wonder if yours is suffering from the same problem.
 
Funnily enough, it was my first thought. But not having any test equipment, I'm restorting to any solution I can before I start getting replacement parts.

Is a G4 power supply easy to replace?
 
OK. I've tried all the advice given, and still nowt.

So, I'm resigned to a new power supply (possibly?). These are £90 refurbished from applemacparts.co.uk.

I'm wondering how much I'd get if I cannibalise my the mac and sell the parts seperately, to fund the purchase of a new computer. What are these things worth these days?

- 2 x Formac TFT screens (21")
- 80GB HDD
- 3 x 512MB memory modules

Kind of dreaming of a £3000 upgrade now... and wishing I had the dosh!
 
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