My old iMac G3 won't start up - Help needed to fix the problem

Hi up,

Recently I start moving all the mess in the shelves and find this old iMac G3 I didn't use for ages. I thought can be a good idea give it to my 7 year old niece as is very nice first personal computer.

The problem it's as I try to boot up, it doesn't look to do nothing.

Last time was used, works properly- few years ago. Now, I clean it, plug the keyboard and mouse and plug the power in. Press the power button and I can hear a electric sound- like when you start a CRT monitor, followed by three small electric sounds, I don't know how to describe. Then any time I press the power button hear the same when plugged. Unplugged there is not any sound coming from.

Following the advices I find in my research, I have changed the motherboard's battery with a brand new one and manually resetting the PMU pressing the CUDA button. I repeat this operation a couple times to ensure I am not doing it wrong, and have the same result. I still having this sound when I try to power on and no other signal of life coming from.

I really want to fix it and set up for my niece, so I look a lot on the web but I cannot get more information on this problem more then what I tried before with the PMU.

So, if anybody have any idea of what's going wrong with this machine and can give me some help or advice to fix this problem, I'll be very gratefully.

It's a iMac G3 400Mhz with Slot Loading DVD.

All the best and thanks in advance.

This may take a few "probing" questions to get a better idea of what is going on:

- Does the iMac G3 monitor power up at all (any light on screen)?
- does the hard drive start to spin up (can you hear it)?
- as far as the three beeps when you turn it on...this is usually not good...read this:

Cure your beeping Mac

Try removing the ram & replace it...making sure it is well seated. It is also important to know that you need to have the correct ram installed. Having the wrong ram in this computer could also be causing problems.

Hope this helps,

- Nick

Welcome to Mac-Forums!

First question - does anything show on the screen after you try to power the iMac on?

Second - do you have the original disks (CDs) that came originally with the iMac?

Thank you for the welcoming and the replies,

Not at all, there's nothing coming from the computer. Screen don't turn on, power light don't come on, there's no any sign of movement on HD's or any other thing. I don't know how to explain accurately the sound I receive when I press the power button. Do you guys remember when still have the old tube television? When you press the power button first you have this sound like coming from a resistor. This is the sound I hear, and then two or three more coming also from resistor, different and low. This are the only signs of life I get from... What do you think?

And yes, I have the original disks that comes with. I just found it in the mess too. One install and one recover.

centralpages said:

Not at all, there's nothing coming from the computer. Screen don't turn on, power light don't come on, there's no any sign of movement on HD's or any other thing. I don't know how to explain accurately the sound I receive when I press the power button. Do you guys remember when still have the old tube television? When you press the power button first you have this sound like coming from a resistor. This is the sound I hear, and then two or three more coming also from resistor, different and low. This are the only signs of life I get from... What do you think?

Click to expand...

The sound you seem to be describing (like from an older CRT TV...which is what the monitor on an iMac G3 is)...is what I would describe as a "static electricity" type sound.

You mentioned "three small electric sounds" in your original post. Are these "beeps" or other sounds?

Also...are you ABSOLUTELY sure this iMac G3 worked fine the last time you used it 3 years ago...or are the problems it has now...the same problems it had 3 years ago when you last used it...and that is why you were no longer using it in the first place?

This may seem like a silly question...but sometimes the mind plays "tricks" on us trying to think back 3 years (or more) ago!

- Nick

Not silly at all Nick, I try to remember and as long as I can, the computer worked before. I take it apart cause I buy the Powerbook G4.

Sorry, when I say the three sounds, I don't want to make a confusion with the RAM beeps. No, definitively this sounds are not beeps. They sounds like electricity starting a resistor, or as you call static electricity. There's no other thing coming from.

Must I be scared?

centralpages said:

Sorry, when I say the three sounds, I don't want to make a confusion with the RAM beeps. No, definitively this sounds are not beeps. They sounds like electricity starting a resistor, or as you call static electricity. There's no other thing coming from.

Must I be scared?

Click to expand...

Is the sound like a "Pop, pop, pop..."?

If so I believe this is something to do with the power supply or the flyback transformer (which powers the CRT display)...which could explain why nothing on the computer is powering up (the light on the screen, or the hard drive spinning up).

I have 3 old iMac G3's...and one of them is making this "Pop, pop, pop" sound. It still works fine...but one of these days I'm afraid it will finally give out!

FYI...if it helps at all. These old iMac G3's can occasionally be found for only $10-$20 dollars. Although I do see people selling them for $50+ on Craig's List. So if your iMac G3 truly is "DEAD" ...it's really not a HUGE financial loss.

- Nick

Course I know- was for years on a shelf and I not pretend to make any benefit for it nor I consider is a loss of money. Just I feel I want to do something with, since I don't like to take it to the rubbish or collect it in a shelf for ages, so I find give it to my niece it's a very good idea and I want to do my best to accomplish it.

No, it's not the same sound you describe as a "pop" Nick.

I am looking forward to open it and start searching for the wrong part. Any idea where I have to start? Maybe the power unit?

No. No no no no no! I can't say this enough, do NOT open an iMac and fool with it. Those things have large capacitors that will hold a charge for years. Enough of a charge to kill you. It isn't worth risking your life for this beautiful, but inoperative computer.

centralpages said:

I find give it to my niece it's a very good idea and I want to do my best to accomplish it.

Click to expand...

It is a very good idea!

No, it's not the same sound you describe as a "pop" Nick.

Click to expand...

Crackle? That could be caused by arcing within the power supply, or between soldered contacts, thanks to build-up of dust.

I am looking forward to open it and start searching for the wrong part. Any idea where I have to start? Maybe the power unit?

Click to expand...

With all due respect to J-J and warnings, opening up an iMac is NOT fraught with fatal risk. However, be sure to dissipate the residual charge in the CRT. There are lots of advisories on how to do that - just search with Google. I've sent you a link to an iMac technical manual via Private Message.

Good luck! Hugh

Just to add my 0.02 to the discussion.
It sounds to me like the OP is describing the kind of sound made when a monitor is degaussed. I've tried searching, but have come up dry on a sound sample that the OP could compare with what he's hearing.

So, if don't hear reply from me in the next five days, it is mean Jamie-Jamie was right about the risks of the iMac inside works. I know how dangerous can be a CRT screen and sure I will take care before put my screwdrivers on.

Hugh, thanks so much for the link, it's simply amazing. I just download the service manual and found the official procedure for this problem. Next step in my case is test the power fuse, so it will take me so many days since I am very busy. Let's see.

What is the OP?

OP means Original Poster - AKA topic starter

If it's a Bondi Blue (300MHz or lower) it sounds like the flyback has gone. happened to me 3 years ago, absolutely no point in trying to repair. Cheaper to go fix another for your niece.

From 1st post:

centralpages said:

It's a iMac G3 400Mhz with Slot Loading DVD.

Click to expand...

Good luck centralpages!

Is it more of a crackle sound. Unplug the hard drive ribbon and see if it starts up with a flashing ?.

Hey centralpages,
I'm just wondering, I bought an imac g3 from ebay, and it was working until I unplugged it from the wall to move it. When I plug it in now (Not when I press power) I get a sort of crackle sound. Is this the same problem that you're having?

Unfortunately though, even if we have the same problem, I would have no solution. (I'm not good with hardware)

But it would be nice to know that someone else shares my problem.

Thread is 6 years old! Have not seen a post from centralpages before.