iMac Bondi Blue confusion

[Blkant]

Many years ago my original Bondi Blue iMac died on me, in the middle of using it it turned of and after taking it to an Apple shop at the time they told me it was dead due to an Analog board (or so I think after all these years). Given the cost to repair it, it was too much to have him repair it. As of late due to some free time (finally...) and sort of an iMac fever over the new model , I have decided to go back and hopefully repair my old Mac before it becomes impossible.

The issue as I remember was it wouldn't turn on any more after that one abrupt shut off during use, given that I can't recall the exact issue, I looked into what could be the reason in hopes I could fix it or replace the part myself at a relatively low cost. After some looking I found one of the most common issues was the battery on the logic board. Given that I decided I would check to see if that is was maybe the issue then, or could be now anyways, I decided to look into it, but by a whim I decided I would plug it in and see what happened anyways. It turned on... For a second or so. The computer ran for a few seconds with an orange light as I think I remember it doing back then, made the noise, then abrupt shut itself off again. It wouldn't do it again as the old issue was.

After this I've become all the more confused... I began taking it apart to see if the battery was an issue only to now discover that the person who inspected it for me didn't put all the screws back in... he left it a mess inside. Depressing... Upon now getting to the battery too, its at 1.176V, well below its 3.6.

So, what is going on here... From what I've read it wont run period without that battery anyways, so that is a must I guess, but could it also be that simple? But then why did it start up at all for those few seconds?

Any help would be greatly appreciated. I know the iMac has no real use any more, but it was my first computer that wasn't a hand me down or leftovers from somewhere, my first REAL computer when I was a kid, so I can't help but feel I need to bring it back to life and let it say hello to its brothers.

 

[bflowers]

Try the battery first, as it won't cost you that much. I kind of doubt that was the problem, since it would have been an easy fix when it first broke. After that, you can try ebay for parts. Might still be salvageable. I think I have a Bondi Blue (might be a Blueberry) in the basement that the kids play a few games on. Safer to let them bang on it than my MacBook.

 

[Blkant]

Try the battery first, as it won't cost you that much. I kind of doubt that was the problem, since it would have been an easy fix when it first broke. After that, you can try ebay for parts. Might still be salvageable. I think I have a Bondi Blue (might be a Blueberry) in the basement that the kids play a few games on. Safer to let them bang on it than my MacBook.

Well I swapped the battery and as expected it didn't resolve the issue. Never the less though I take some satisfaction in that it needed to be done anyways. :/

I'm not sure where to go from here though, seems logically I would have to replace either the logic board or power supply. Any ideas on how I should go about this?

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There is one other really odd thing that maybe can help narrow down what is causing this. If I let it sit for several hours unplugged then try turning it on again, it starts. The light turns orange for a while, you here the chime, and then the second it turns green the whole thing powers off. If I try again right after, it does nothing at all, not until I unplug it again for some time.

When I first plug it in after a while too there is an odd noise from the CRT area, though that doesn't say much as thats the only place you can really hear noise from. It sounds almost like air slowing leaking out of a valve or balloon. After its first attempt at starting up it doesn't make it again either. I can't recall if that was normal or what.

It just doesn't make any sense... :/

 

[bflowers]

Well, to me, and I have limited knowledge when it comes to electrical engineering, I would think there is a bad capacitor somewhere. The way it will attempt to start up after sitting several days is what leads me to that conclusion. I guess I would say try finding an old one for parts on ebay. You might get lucky and be able to swap out the right part.

As for the sound from the tube, it could also be that the charge on the tube is dissipating over time, and you are hearing that. That was one thing my dad always warned me about taking anything with a tube apart. First thing I was told to do was use a long rubber handled screwdriver to discharge the tube.

Good luck.

 

[Slow Programmer]

I am not sure I would put a lot of money into it. I purchased one of those last year on ebay for $7.00 usd and it works perfectly. The shipping was $20.00. You can still find these in good working order for a few dollars. If nothing else find and old one for a few dollars to use for spare parts.

Headgap is a good place to pick up parts for these old machines too.

http://stn2.headgap.com/resale/FMPro?-db=OrdersC.fp3&-format=products.htm&-new

 

[Lucianrider]

Check around the high voltage plug where it connects to the side of the tube for arcing. Dust can allow a conductive bridge to form which will cause a similar noise that you hear.
Pull the cable out and thoroughly clean the tube and connector before replacing the cable. Some dielectric grease might help but very sparingly.

But I agree with the notion that a capacitor is probably gone. Check for bulges or splits.