Bondi Blue iMac Power Issue

[Juliet Elysa]

I had a feeling that's what would happen. If the power button were stuck in the on position it would make more sense for the computer to have problems shutting down.

A couple days ago I did a quick Google search for instructions on how to take apart one of these Macs. It looks doable, though seems a bit complicated to a person who's never done it before. Can anyone point me to a recap and/or soldering tutorial or something for someone who's never done it before?

 

[XBHS1997]

Don't know if you've already found that: http://jbdkz.hubpages.com/hub/replacing-the-power-supply-in-an-imac-g3-333mhz-tray-loading-computer

I'd also be interested for soldering tutorial or explanation, one never knows.....

 

[Juliet Elysa]

That's one of the ones I looked at. The pictures were pretty helpful, though it seems like a lot of work.

 

[XBHS1997]

Well, it's true that you need some space, time and nobody disturbing you! ^^ 

Do you think you'll do it anyway?

 

[Juliet Elysa]

I'm seriously considering it, though I can't decide what all I want to do once I have the Mac taken apart. It seemed to be in pretty good condition when it died (other than the power issue that killed it) so I don't know if I should do any maintenance/etc. or not.

 

[XBHS1997]

Hi Juliet!

What's up? Is the iMac still not working?

 

[giolicious]

i suggest you read the troubleshooting part of this document at http://mrjcd.com/tray-load_iMac_repair/imac.pdf. There's a step by step guide in there that can help you troubleshoot the power problem like the one you have.

I have the same issue with my iMac g3 233mhz bondi blue that wont power on. I plug in the AC, press the power button or keyboard power button and nothing happens. Next morning i was gonna open it but when i turn it on again it powered on just fine with the usual chime sound and all.

 

[Juliet Elysa]

i suggest you read the troubleshooting part of this document at http://mrjcd.com/tray-load_iMac_repair/imac.pdf. There's a step by step guide in there that can help you troubleshoot the power problem like the one you have.

I have the same issue with my iMac g3 233mhz bondi blue that wont power on. I plug in the AC, press the power button or keyboard power button and nothing happens. Next morning i was gonna open it but when i turn it on again it powered on just fine with the usual chime sound and all.

Thank you!!! It was hard to find the relevant part, but it made a lot of sense once I found it. Next time I can get the right tools I'll take a look (though I'll admit I'm a bit of a scaredy-cat when it comes to electricity, LOL). And that's great luck with your Mac, is it still working well?

 

[johnklos]

Don't forget to discharge the CRT carefully before you work on it.

My main computer for many years was a first generation iMac, but I was given the motherboard without any other parts, so I built it in to a Tonka truck. Although you lose the aesthetics of the iMac, the form factor makes it easy to build an iMac motherboard in to all sorts of things. Any standard power supply will put out more power than the iMac needs.

http://www.ziaspace.com/hosting/tonka/

 

[Juliet Elysa]

Well, since I don't have a working Bondi keyboard or mouse a family member bought me both on eBay. We're hoping that the power button on this keyboard works, since the keyboard (and mouse) that originally came with the iMac died before the computer did. If everything goes the way we want it to we'll be able to start the iMac with the new-to-us keyboard. If not... at least we'll have a complete set (computer, mouse and keyboard) again!

How do you discharge a CRT? Last (and only) time I tried I did something wrong and got shocked. It obviously didn't kill me, but it hurt!

 

[Schmoburger]

You know, some years ago you could pick up dozens at the same time for 2-5 bucks each, in the best case (sometimes school that changed all their computers) ^^

 Yep, he ones I used to manage in my senior years at high school got thrown away in about 2008... not  even sold, just dumped. My brother got hold of a bunch of slotloads. I got the trayloads a few years before by tender.... picked em up for between 5-20 bucks in various conditions. I have restored a few now, as I always loved them when new... my graphite build thread is somewhere in the Conquest section actually. But yes things certainly have changed a bit... in 2000 i bought a 2 and a half year old 5500 AIO for $250 when the school retired them and replaced them with iMacs. Fast forward 15 years years and now you can get G5's for that.

 

[Schmoburger]

As an aside... have you replaced the PRAM battery? iMac's, Powerbooks and Powermacs alike from this era can be a little fickle about this and refuse to boot with a dead or missing PRAM battery.

 

[johnklos]

How do you discharge a CRT? Last (and only) time I tried I did something wrong and got shocked. It obviously didn't kill me, but it hurt!

Take an insulated wire, connect one end to the grounded metal frame where the screws hold the CRT in to the plastic, then carefully insert the other end under the suction cup-looking rubber that covers the hole where the flyback wire goes in to the CRT. If it has a charge, you'll hear the discharge and may see the spark.

This was actually still on the Apple repair certification tests until just a few years ago...

 

[Schmoburger]

To the above I shall ad, it is a good idea to unground yourself as you do it... stand in a plastic tote box or something or wear rubber soles. That way the easiest way to earth for that 20,000+ volts is definitely not going to be you lol

 

[Juliet Elysa]

IT LIVES!!! Kinda.

The new-to-us keyboard we bought arrived last night, and today we took the iMac out of the closet and plugged it in. When we pressed the button it chimed and started making noise!

The monitor took its sweet time to turn on - when it finally did the computer was already halfway through a startup Disk First Aid check. Apparently the last time it was turned on before it died it crashed.

After I got to the desktop I started looking around in various folders. Everything was working well... and then it randomly shut down. The screen distorted for a second before the crash.

And now it won't turn on again, even with the new keyboard. :'(

The monitor was a bit dimmer than I remember it being before it died the first time (though it was years ago so my memory might be faulty), and  the entire time it was on I could smell that unused electronic dust smell. So, my question is... what now? We know that the iMac has the potential for life, but it's obviously still very sick. A thorough dusting is definitely in its future, that much I've decided for sure.

If anyone's interested, I was able to record the extensions popping up on the bottom of the screen and a bit of the desktop. The video is here.  (Yes, I was crying a little bit at the end. This small glimmer of life was so wonderful to see after all these years!)

 

[CC_333]

It kinda sounds like an analog board/PSU problem.

From what I've read, the tray loading iMacs were prone to flyback transformer failure (which could explain the dimmer than usual screen with the distortion). If I remember though, the more common failure mode is starting up normally, and then shutting down with a loud zapping sound when it tries to engage the CRT, never making it to the desktop.

c

 

[Schmoburger]

Whilst it is very common for flyback transformers to fail in trayload (and even slotload, but they usually fail elsewhere before the fbt has a chance) iMacs, the symptoms you decribe would sound more like failure of the PSU itself. The more common behaviour when the flyback transformer and/or associated caps have blown is for the machine to surge and shut off as soon as the CRT is powered up, sometimes on the sly or sometimes with a loudish zap and a flash even.

The dimness and distortion of the screen prior to the complete failure would seem like a product of insufficient current or voltage to the CRT, which could be explained by a failing power supply given it now fails to boot. That said, there is still a possibility that the analogue video circutry is at fault and that something was drawing excess power or shorted and blew a fuse or other component in the power supply creating the secondary issue. But the intermittent startup issues would point more to an actual power supply issue.

 

[Juliet Elysa]

I'll replace the power supply when I get a chance, and check caps also. I'm thinking of taking some pics to show y'all, maybe you'll see something I missed.

For quite a while before the computer died the first time it was taking several pushes of the power button before turning on normally (which is why the button was a suspect), but I do vaguely remember the screen barely shrinking being the first noticeable symptom. Mind you, I was 12-14 when that started so I could be misremembering. The poor thing sat in my closet for five years before I brought it out to resurrect it. I had to put it back after trying the experiment with a borrowed keyboard a while ago.

Speaking of keyboards, does anyone else find it strange that a keyboard we bought on eBay was able to start the computer when a known working keyboard couldn't? 8-o

The CRT did have some issues when I turned the iMac on two days ago - about a minute between the startup chime and the CRT actually turning on, and when it did work the screen was dim. The only noticeable distortion, however, was right before the computer shut off. And the entire screen changed shape. (I should try to recreate it with Photoshop, it actually looked pretty cool.)

Edit: What type of power supply should I look for? A quick Google search did nothing but confuse me... LOL

 

[Schmoburger]

I beleive Revision's A though D iMac power supplies and analogue boards are intercompatible. It is rather an involved task to remove it, requiring you to take the top shell off the machine, and requires extreme care as there are components in the analogue board/power supply area that can hold a very nasty residual charge, not the least of which is the CRT. If you have a look on my blog you will find a detailed teardown procedure for a slotload iMac... Whilst they are a fairly different ballpark, I assume they sort of go together the same way discounting the lower section, but probably with some screws in different places.

As it stand, if you are tearing it apart down to that level where you have the high voltage side exposed anyway, it may very well be worth having a detailed look at the analogue and PSU board for burnt components, swollen or burst caps, split rectifiers, resistors or diodes etc... with the symptoms you describe, I would expect to see a popped cap somewhere. If you find ones with the ends bulged instead of flat, leaking, or burst, then you have quite possible sourced the problem. If the issue is glaringly obvious, a recap might be the better alternative, as a secondhand board is probably going to be a game of Russian roulette in itself. As it stands, in either case you need to remove the high voltage board/s for replacement or repair, so it doesnt hurt to give the current items a good look over and see if you can spot a repairable problem

Anyway, I look forward to some good news.

 

[Juliet Elysa]

Ouch... did a more thorough Google search and a G3 power supply isn't cheap! 8-o I'll say something in the Trading Post soon, but at the moment I don't have all the tools for a teardown handy and need to find out more about how to be safe around high voltage. I'm a bit paranoid after some less than pleasant experiences around CRTs.