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kyle
9th April 2004, 10:16 AM
Ive been having a problem with my iMac G3 lately. Every so often it just dies.. the normal procedure once this happens is to unplug the power and plug it back in, then turn the machine back on. This happened the other day so i did the normal thing but the machine just wont turn on anymore.

Does anyone have any ideas what it could be?

Cheers.

stickman67
9th April 2004, 04:33 PM
I have no idea, but it doesn't sound good.

Internal power supply?

Crambo
9th April 2004, 07:06 PM
Yeah sounds as if your PSU is no longer up to the challenge, or you've recently added some internal devices (such as HDDs or other physical drives) and hence you're drawing too much power, well too much for your PSU. So, if you've installed such of late, remove them and this should solve the problem. If not, you're in need of a new PSU.

faction
9th April 2004, 09:10 PM
Same thing happened to me with one of my old iMacs. Exactly the same.

Turned out it was the PSU and also the Graphics Unit was dead. They wanted 900 bucks to fix it. So I told them to get lost.

It still sits under the desk. Dead.

Currawong
9th April 2004, 10:23 PM
You could try pulling it apart, removing the PRAM battery and letting it sit for 24 hours. It might be a flakey PMU - removing the battery for a day resets it fully. I've recovered dead "New World" machines (iMac/G3 B&W onwards) this way.

pipsqeek
10th April 2004, 10:14 AM
You can find these batteries at Jaycar or Dick Smith. The latter being more expensive.

If you find its not the PRAM then the PSU may well be stuffed. Usually when one components goes in them, it starts a domino effect, the fuses are useless from my experience.

You may find that a resistor is blow, either gone high or short....this leads to capacitors breaking down and blowing from excessive voltage.

Computer PSU's are complex because they have to provide numerous amounts of regulated voltages. To make one at home would cost twice as much as it would to buy one.

If you have a multimeter you can set it to DC volts and turn the PSU on to see what voltages are coming out of the motherboard plug...unplugged from the mobo that is.

The PSU might has a sticker on it that tells you what colour wire has what voltage. commonly 3.3V, 5V, 12V according to most PC PSU's, I have never opened up a new generation mac to know for sure.

This is also not a definate test, as voltages may be spot on but current capacity may be unable to handle the required amount needed, quite an amount.

If you have no experience with electronics. please do not be tempted to test anything. Your better off (safer off) sourcing a new PSU for a few bucks and seeing if that works.

Nothing can be put in concrete because of so many factors. But I would agree with most of the previous posts. Its either PRAM battery or PSU.

When it does turn on, have you noticed what the system time is? as well as the date? this I think, would give you somewhat of a clear indication of the condition of the PRAM battery, atleast if it is faulty or not.

Steve

LCGuy
10th April 2004, 04:51 PM
I'd say that the power suspply is either overheating or dying. Do you have air conditioning in the same room as the iMac? If you do, then the PSU's dying. If not, consider it overheating as another possible problem. Also, what kind of iMac G3 is it? Is it a tray load iMac or a slot load iMac? This will help as a lot, as tray loaders internally are very different to slot loaders.

kyle
12th April 2004, 09:39 AM
Its a tray loading one.. ive acctually got it to work now, just switched power points and it worked? But it still has the problem that it just dies every so often, ussally when theres a big load. So im guessing its over heating or soemthing? Cheers for the replies guys.

pipsqeek
12th April 2004, 10:08 AM
Does not neccesarily mean its heat. Could be, but when a big load is computing....your HDD will thrash away, increasing the current flow. Your CPU will more than likely be using more power to compute what it is 'Big load".

Ram will be used. essentially as the current flow increases, the powersupply can only let out so much. Until it will start to break down. The capacitors will not be allowed to fully charge, therefore not doing their job. I can go into it much further but you are on the right track of it either being heat or too much power consumption.

Steve

LCGuy
12th April 2004, 12:27 PM
Sounds like the Power supply is on its way out. :(