Imac g3's screen wont display anything when pressing power button?

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Imac g3's screen wont display anything when pressing power button?

The Imac i am having trouble with is the late 98 bondi blue imac and every time i press the power button to switch it on, the crt screen won't display a thing.

At times i've waited a few minutes after pressing the power button and still no joy.

Another thing that i've recently noticed is that the power button is illuminated in a sort of red/orange when the screen problem is going on.

Could this by any chance be some sort of hardware error or could it be something about the operating system?

Im really not sure the slightest bit and any information about this will be very much appreciated.

To put another thing into perspective, i just got this computer back the other day from my friend who's has had it since the early 2000's while i had to keep up with an xp all that time... until a few months ago with the new imac!

Anyway, the reason i want to repair it is that it's still a brilliant piece of hardware and certainly has enough life to keep it from the scrap heap just yet.

The last time i saw the bondi imac in operation was a few months ago and was working very stable on it's native OS 9.2.

Im pretty certain however it's still operating on 9.2 and what would be good solutions about the monitor and the power button?

Info regarding this will be much appreciated

Thanks for looking

niall a.

Message was edited by: Jerzie

Imac 20 inch (early 2008), Mac OS X (10.5.7), It's a pretty darn good computer!

Posted on Jun 6, 2009 3:45 PM

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Answer 1

Jun 6, 2009 4:03 PM in response to Jerzie

So it's one of the tray-loader G3 iMacs, correct? (Not a slot loader)

What you describe sounds like a failure of the analog video board. This is the component that powers and supplies the high voltage needed to operate the CRT display. The specific part on the board that usually fails first is called the flyback transformer. Because of the failure, the iMac does not pass the internal startup self-test, and shuts off.

This board is in the portion of the case that is not user accessible, with high voltage present (even if the iMac is disconnected from power), so it is not something you want to replace yourself unless you know what you are doing.

You can test if this is the likely cause by doing the following. Open the bottom panel. Disconnect the internal video cable that goes between the internal chassis (where the drives, CPU, and logic boards are located) and the rest of the iMac. It's the only one that looks like a video connector, with the two screw in hasteners. Keep the other two cables connected.

Start the iMac. If the problem is the analog video board, it should start up, because you are bypassing the internal video. You will obviously not see anything on the display, but you should be able to tell by the sounds it makes. When it sounds like it has gotten to the Desktop, you can shut it down properly (without seeing anything) by pressing (and releasing) the power button and then the Return key.

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Answer 2

Jerzie Author

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Jun 6, 2009 4:19 PM in response to Kenichi Watanabe

Yes. It's the tray loader edition and i think it is the bug fixed late 98 system that replaced the mid 98 one.

Many thanks for information and solutions, they are very professional and in depth!

Im guessing that it might well be the video card connections like you pinpointed there

For the crt it might well need some professional attention as i've heard that the cathodes and electrodes within the tube are still active for weeks after power deactivation.

I will try some of your recommended procedures and thanks again

niall a.

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Answer 3

Jun 6, 2009 4:35 PM in response to Jerzie

Im guessing that it might well be the video card connections like you pinpointed there

To clarify, it's not the "connection" that is the problem, it's the analog video board itself. Also, the analog video board is not the "video card," as the term is used for more recent computers. The iMac has old ATI graphics chips (what is typically referred to as the "video card"), and they are on the motherboard. The problem is not there. The analog video board, on the other hand, is a component that is really part of the CRT. It is located along the side of CRT; the power supply board is on one side and the analog video board is on the other. The same type of part would be inside an old CRT display and even old TV sets.

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Answer 4

Jerzie Author

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Jun 6, 2009 4:50 PM in response to Kenichi Watanabe

thanks for clarifying further info.

So really it's more to do with the crt's components than any other.

Just curious, but what manufacturer supplied the picture tube for apples g3 systems or were the imac crt's researched and built in-house by apple themselves?

Because if the monitors were made by a big tv manufacturing corporation maybe they could show some guidance and walkthroughs for crt maintenance and reparation, although they might not advise someone with basic knowledge of crt's into repairing a crt.

Out of interest, can an official apple store fix discontinued systems such as the bondi or is there any other retailer that solely specialize in repairing old apple systems?

Many thanks again for looking

niall a.

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Answer 5

Jun 6, 2009 5:45 PM in response to Jerzie

The tube itself is a standard design (I think), so it was probably supplied by more than one manufacturer (like LG or Samsung), just as LCD's used today may come from more than one source. It is definitely not a Sony Trinitron tube, because those have a unique one-way (side to side but not top to bottom) curvature. The iMac's screen is slightly curved from top to bottom and side to side.

The analog video board was a proprietary design, created to fit the space constraints in the iMac's rounded case. Apple did not build the parts, but they probably designed it. Unfortunately, that is the part with the problem.

Getting complete replacement boards is an iffy deal, because any boards you are likely to find are used and old themselves, so they can fail soon after. No one is making new complete analog video boards for tray-loader G3 iMacs. The flyback transformer issue on the analog video board is the most common reason for CRT iMacs to fail. If you do a Google search using the info already provided, you may be able to find additional information about repairing the board itself.

But that would require expertise and equipment most people do not have, and again, working beyond the user accessible portion of CRT iMac is dangerous and not recommended, unless you have such skills and knowledge.

To get it repaired, you are probably better off going to a non-Apple authorized repair business. You may be able to find such service using this web page

http://www.apple.com/buy/locator/service/

EDIT: Actually, that for the U.S. Maybe this page for UK.

http://www.apple.com/uk/buy/locator/

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