Imac G3 will not boot, gets mac chime seldomly

JamesAvery22 said:

A friend threw me a dead Imac.

I plugged it in and hit the power and go the mac chime but nothing else and it just turned right back off. Screen never came on. Then if I hit the power button nothing happened.

If I leave it unplugged for awhile I can reproduce the same symptoms.

I believe, at the support desk I use to work at, we had the same model imac doing the same thing. He replaced the powersupply and it fixed it.

But searching for parts I saw that there are 3 main parts for the power supply.
The ps board, the ps Down Converter Board, and the Filter Power Supply.

Can anyone point me in the right direction? Thanks

James

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It could be any one of the three or a combination. Replace all three to be sure.

JamesAvery22 said:

A friend threw me a dead Imac.

I plugged it in and hit the power and go the mac chime but nothing else and it just turned right back off. Screen never came on. Then if I hit the power button nothing happened.

If I leave it unplugged for awhile I can reproduce the same symptoms.

I believe, at the support desk I use to work at, we had the same model imac doing the same thing. He replaced the powersupply and it fixed it.

But searching for parts I saw that there are 3 main parts for the power supply.
The ps board, the ps Down Converter Board, and the Filter Power Supply.

Can anyone point me in the right direction? Thanks

James

Click to expand...

AASP's and the Apple Store have the training and the tools to verify which part(s) need to be replaced. Generally, this sounds like Power/Analog Video board or Logic board, but if you could elaborate a few things for me I might be able to at least give you advice on where to take it.

What type of iMac do you have - is the optical drive a tray-load or a slot-load model? If it's a tray-load, it's really not worth fixing. You could take it to an AASP and see if they will buy it off of you for parts. If it's a slot-load, there's a chance that the fix could be quick.

You say that you turn it on, you hear the chime, and then very shortly after the machine turns off. Is there any sort of noise accompanying the machine powering off? How long after the chime does it turn off? Does the power button light come on at all?

I hope we can get a working machine for you.

JamesAvery22 said:

A friend threw me a dead Imac.

I plugged it in and hit the power and go the mac chime but nothing else and it just turned right back off. Screen never came on. Then if I hit the power button nothing happened.

If I leave it unplugged for awhile I can reproduce the same symptoms.

Click to expand...

Which iMac G3 is it? I had the same thing happen to my 233 MHz Rev A, but I was using it when it died. The monitor popped and sizzled and then whenever I tried to turn it on afterwards it would either chime and shut off or nothing at all.

Luckily I had an old Apple monitor that I used with a Performa 6220CD because inside the iMac 233 is an old style monitor connector. I disconnected the internal monitor cable and plugged in the external and wa la! It booted and to this day it still works!

If you don't have an old Apple monitor (pre ADC) you should be able to find a Mac to VGA adapter cheap.

Let me know if you have questions, I can be more detailed.

JackRipper said:

Which iMac G3 is it? I had the same thing happen to my 233 MHz Rev A, but I was using it when it died. The monitor popped and sizzled and then whenever I tried to turn it on afterwards it would either chime and shut off or nothing at all.

Luckily I had an old Apple monitor that I used with a Performa 6220CD because inside the iMac 233 is an old style monitor connector. I disconnected the internal monitor cable and plugged in the external and wa la! It booted and to this day it still works!

If you don't have an old Apple monitor (pre ADC) you should be able to find a Mac to VGA adapter cheap.

Let me know if you have questions, I can be more detailed.

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Hehe. I was trying to avoid having him check that. But yeah, that's the flyback transformer. A lot of certified techs diagnose it "wrong."

I put "wrong" in quotes because, to my knowledge, it's not a part you can order - Apple has you order the whole PAV for it. Some places sell it used and an AASP will probably have a few older iMacs they can scavenge parts from.

you may want to check the clock-battery as well. it is probably too young to need a replacement but the symptoms sound similar to a dead clock battery.

JamesAvery22 said:

Where is the clock battery?

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The clock battery is called a PRAM battery and is located on the logic board (on a volt meter it should read around 3.6 volts. Any less and it should be replaced). To get to it you will have to pull out the logic board carrier out. A faulty battery can cause some strange things to happen, but usually only with really older computers, always worth checking out first though (cheap to replace and easy to test).

It sounds like either an analog board or a power board and less likely a logic board. You could try the following if you want.

FOLLOW THESE INSTRUCTIONS AT YOUR OWN RISK!

1. Find a safe place to put your computer screen face down.

2. Take off the the bottom plastic cover. Undo the screw at the top and yank the handle up and out.

3. OK. Now what you will see is the logic board carrier with either 3 or 4 cables plugged into it. 2 from the left (colored cables) and either 1 or two from the right (grey cables). Unplug the biggest cable coming from the right.

4. Plug the computer back in and turn it on. If the computer has power and stays on (the screen will stay blank becase you have just disconnected the analog board) the most likely cause of your problem will be the analog board. If it does the same as before it will most likely be the power board.

Have fun!

and tell us how you get along.

Nice idea Jackripper!

If you're not comfortable doing those steps, see if you can find a local AASP that will check it out for you. At the very worst, you leave the machine with them - not like it's worth any money to you anyway.

JamesAvery22 said:

Uh which connector am I supposed to unplug?

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This one is the internal monitor connector. This is where I plugged in an external. If you don't have an old apple monitor you should be able to find a cheap (pre ADC) mac to vga adapter.

JamesAvery22 said:

Unplugged it and still nothing. Ordered a new power board for 30$. Hopefully this will fix it Thanks for your help everyone I really appreciate it

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If you didn't plug in an external monitor it won't do anything. As far as I can tell the iMac will not boot without a monitor.

Anyway, I hope that power board does it for you.

JamesAvery22 said:

What Judo said was incorrect? Yeah I definitely hope a power board fixes it too

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I'm not sure, he sounds like a tech, I'm just going off a previous experience with my iMac since it sounded like the same thing was happening to yours.

My iMac would not boot until I connected a working monitor to it. Maybe the power board will fix the internal monitor?

you have been at this so long james! don't give up now! I admire your stamina through this. most people would have scrapped it by now

My 333 did this once oddly enough it was the hd ran diskwarrior from boot and repaired it try that prob wont work though i think my imacs hd was possesed every couple months wont boot right time to repair

I have heard people having simerlar problems. They fix it with the PMU button. If that model has a PMU reset button try that! It is on the mother board. Make certain the power cord is unpluged, and only press it once!wait ten seconds then pug the mac back in and turn it on. Hope this helps.