Bondi iMac won't boot

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Tom Owad's picture
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Bondi iMac won't boot

I have a Bondi iMac that begins to power up, chimes, then shuts back down. I'm figuring that's either the analog board or power supply. Anybody know which is more likely?

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i would say analog board, it

i would say analog board, it it starts and you get the chime, thene the power supply is probably ok. It souynds like a classic case of a bad analog board to me. :coolmac: :mac: :macos:

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Analog Board == Power Supply.

Analog Board == Power Supply.

(They're the same component. The question is whether it's the "power supply" section that failed or the flyback transformer.)

Does the system work if you use an external monitor (Via a Mac->VGA dongle.) with the internal screen disconnected? Ocassionally "weak" analog boards will suffice to power the computer if the monitor is prevented from starting.

--Peace

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They're seperate components.

They're seperate components. The analog board (661-2080) is on the left of the CRT and the power supply (661-2081) is on the right.

Anybody know which part is the more common failure?

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I'm going to assume that it's

I'm going to assume that it's the analog board that fails more often. Power supplies generally are built to handle more than their rating. Since analog boards deal with high voltages and are (somewhat) temperature-sensitive, it should be the flyback transformer et al that dies first. It's also how an iMac with a dead monitor can still boot properly (albeit without video)--the power supply is fine even though the analog board is dead.

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Re: They're seperate components.

They're seperate components. The analog board (661-2080) is on the left of the CRT and the power supply (661-2081) is on the right.

Anybody know which part is the more common failure?

Yeah, I realized that after a bit of thought later. Anyway.

The thing that kills the video in those machines is almost always the flyback transformer (which is on the analog board). A crony keeps telling me it's easy to get a replacement for just that component, if that's the problem. (I still have the monitor portion of the iMac I got my extra motherboard from, and he's just enough of a Mac-head to not like the idea of it ending up in a landfill. Frankly, I'm skittish about trusting my soldering skills to high-voltage components.)

The fact that it powers off makes life more complicated. If you have a monitor adapter I'd try booting it with an external monitor. If that fails, then it may well be the power supply.

--Peace

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Me Too...

I also have a bondi iMac that will start up, but then will shut down whenever it feels like it. Strange thing, though, is that if I start it up with extensions off (OS 9.something) it will stay up almost indefinitely (or at least as long as I have patience to wait for it.) I've tried attaching an external monitor to it, and it does the same thing, with & without extensions loaded.

If this is a bad flyback, I'd like to replace the thing rather than gut it; Anybody got any ideas?

Any links to instructions for doing the repair would also be welcome.

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Re: Service Instructions/Manual

You can download a Service Manual here: http://www.whoopis.com/computer_repair/

Cheers, Tom
Mac Troubleshooting, Maintenance & Tips
http://www.geocities.com/texas_macman/MacTroubleshoot.html

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iMac recovery

To get past the iMac boot-up problem described here (start, green light for a few seconds, powerdown with "zap" noise) I hooked up an external monitor to the available VGA port in the back of my iMac DV. I took off the rear panel, and unscrewed the RGB cable from the motherboard. No joy; I didn't even get it to power on. I replaced the RGB cable and the previous symptoms reappeared.

Did I properly bypass the internal monitor by unplugging the RGB cable? Or is there another cable that should be unplugged? I've seen many references to this technique, but no definitive identification of the cables involved.

I really would just like to get the data off my hard-drive. I assume I can unplug the drive and plug it into another mac with an ATA bus.

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Re: iMac recovery

I really would just like to get the data off my hard-drive. I assume I can unplug the drive and plug it into another mac with an ATA bus.

This you can do.

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