Dead, dead, deadskies. Help please?

[LCGuy]

Well last week I powered up my iMac to discover it had gone deadskies. It'd boot to the Apple logo (Jag 10.2. 8) , and then freeze, and display static. (like a bad digital TV picture, sort of)

I've tried a 10.1.3 CD, it kernel panics. I've tried both OS 8.6 and OS 9.2.1 CDs, and on both of those it will either hang on the Happy Mac or the "Welcome to Mac OS" greeting.

I've tried switching out RAM. I've tried switching out CPU cards. I've tried switching mobos. I've tried using it with an external monitor (all my diagnostics have been done on an external display to nullify any issue with the PSU not putting out enough power). I've tried resetting the CUDA.

Last Saturday when I first discovered this, I pulled the PRAM battery and let it sit for a week without the PRAM battery. This afternoon I got it to boot all the way into OS X 10.1 (booted from the CD) exactly once. It has never done it again.

Anyone got any ideas as to how I can get 'er going again, or is she gone for good this time?

Edit - I neglected to mention, its a tray loading iMac 333 (Rev. D)

 

[Da Penguin]

Have you run it through an apple diagnostics disk to have it check everything? I know it sounds weird, but a looping ASD has found many a tricky thing for myself.

Also, even with using the external, PSU issues could still be lingering causing activity like this. If you have the means to try other power options, I would definitely go for it. My most recent re-hacking of an iMac didn't have these problems, but incredibly intermittent hard crashes, and it was due to a bad PSU that took forever to narrow down.

Best of luck mate,

TBird

 

[LCGuy]

Sadly the tray loader pre-dates any sort of Apple Hardware Test CDs...IIRC they came in with the Summer 2000 imacs.

I've noticed that in the months before it died, its been taking longer for the display to warm up, despite the fact that the system has always powered on straight away. (in fact the last time I used it before it died, by the time the display had warmed up enough for it to display an image, the machine was fully booted and ready to roll)

I've got several ATX PSUs kicking around, maybe it might be time for me to at least try doing an ATX hack...

 

[Anonymous Freak]

Wait....

You tried switching RAM, CPU, and motherboard, running on an external monitor, yet it still fails?

That strikes me as it MUST be something in the power supply. The only other option are the ATA cables. (Which can be confirmed by doing the ATX hack.)

 

[LCGuy]

Yeah...the thing is, the other motherboard doesn't even chime. The motherboard thats in it now chimes, and comes up with an image, like I said, it just doesn't boot. (either it hangs on the Happy Mac, or KPs if I try to boot into OS X) Before I try the ATX hack, one thing I'm thinking - the early iMacs have a seperate power filter board on the bottom of the logic board tray. Maybe I ought to try swapping them around...if I still don't get any joy, its time to try the ATX hack. (despite the fact that I *really* don't want to if I can help it )

 

[LCGuy]

Well you're not going to believe this, but it seems to have come back to life again. I just sat down with it and tried various arrangements of CPU, motherboard and RAM. Eventually I got to a stage where the machine could boot into either OS 8.6 or 10.1 successfully. After that I tried adding the 4MB SGRAM stick. Then an extra RAM stick. Then the hard drive, then the CD-ROM drive. Now its sitting on my desk all closed up, all in one piece, and it seems to be working fine now. I guess the question is though, how long for?

As you said, AF, I'm certain that it could be the PSU at fault. After I got it booting off the HD, the first thing I did was boot into OS 9 and run TTP, and loop the diagnostics tests 100 times. It passed with flying colours. That puts my mind at relative ease in regards to the RAM. Either way, if it dies again, I'm going to seriously entertain the idea of doing the ATX hack. I know something in there is definitely dying - I've got it running on the internal display, and although this is quite rare, sometimes the display will flicker, and it will make a click sound, the sort of sound that comes from a relay. This only happens for a second, and it doesn't happen very often, but it does happen. Also, on some mornings when I go to boot it up, it will take a while for the display to fully warm up. Often by the time that you can see an image, the machine is fully booted and ready to go.

So yeah, thats where I'm at now. I'm actually typing this on the iMac itself right now, connected to the internet via the P3 (which died this morning, though was easily fixed, graphics card needed reseating), while listening to AC/DC - Heatseeker. Life is good

 

[kissmyash933]

Well you're not going to believe this, but it seems to have come back to life again. I just sat down with it and tried various arrangements of CPU, motherboard and RAM. Eventually I got to a stage where the machine could boot into either OS 8.6 or 10.1 successfully. After that I tried adding the 4MB SGRAM stick. Then an extra RAM stick. Then the hard drive, then the CD-ROM drive. Now its sitting on my desk all closed up, all in one piece, and it seems to be working fine now. I guess the question is though, how long for?
As you said, AF, I'm certain that it could be the PSU at fault. After I got it booting off the HD, the first thing I did was boot into OS 9 and run TTP, and loop the diagnostics tests 100 times. It passed with flying colours. That puts my mind at relative ease in regards to the RAM. Either way, if it dies again, I'm going to seriously entertain the idea of doing the ATX hack. I know something in there is definitely dying - I've got it running on the internal display, and although this is quite rare, sometimes the display will flicker, and it will make a click sound, the sort of sound that comes from a relay. This only happens for a second, and it doesn't happen very often, but it does happen. Also, on some mornings when I go to boot it up, it will take a while for the display to fully warm up. Often by the time that you can see an image, the machine is fully booted and ready to go.

So yeah, thats where I'm at now. I'm actually typing this on the iMac itself right now, connected to the internet via the P3 (which died this morning, though was easily fixed, graphics card needed reseating), while listening to AC/DC - Heatseeker. Life is good

LC, if the display flickers and makes a click sound, that sounds like your Flyback transformer is going bad, which is something that is extremely common on early iMacs. im sure you can find an analog board or a flyback somewhere, the flybacks are easy to install, just unsolder the old one and pop a new one on and attach the anode to the tube and your done.

that might not be the problem though, and if it doesnt do it often, its probably going to take it a while, my Studio display took over 2 years to die with a bad flyback.

Blake.

 

[equill]

Don't, without deliberate testing, discount the rôle of the Mac's mains cable in all this. I have had a Snow 500 iMac since new. It has now been always-on since about 1983 but for a RAM upgrade and a new battery. Its MLB failed within three weeks, but since its replacement under warranty the only failure has been obdurate KP-ing a couple of months ago. 'Only' but for an episode of three or four weeks several years ago, while the iMac was still used in OS 9.1, in which it would 'fizz' once and black out, but reboot after a few minutes. Pure accident—unplugging and replugging the original rainbow mains cable—showed that the silicone cladding of the cable was allowing the connectors inside the female end of the cable to lose contact enough to arc over to the Mac's mains-input socket.

I let the Mac rest after the recent KP episodes because there were other things to do. It was now an OS 9.2.2/10.2.8 machine. I redistributed RAM between several iMacs, including the Snow, to give them 640MB each. Almost idly I tried to boot the Snow, and voilà! Back to its old self, as which it has remained now for four-or-so weeks.

I anticipated similar behaviour when my blue 17" CRT Studio Display began erratically fizzing recently. The display shrank and expanded with each fizz, but never blanked. Despite the marque's reputation for FBT failure I persisted to use it. Sometimes it was entirely trouble-free, and on other occasions I switched it off because the fault was persistent after about 10min. of use. Usually, but not always, firming the mains cable in the male socket delayed or prevented the onset of trouble. So I cannot yet be definite about the display's problem, but I don't discount the power input.

Finally, as reported elsewhere in these threads, a recently-acquired Plus 1MB was converted from a garbled-screen hulk into a working Mac by replacing the mains cable. In all of these anecdotal occurrences (I haven't physically tested any of the suspect cables) my impression was that the mains cable's IEC-C13 plug had slid into the Mac's socket rather too easily, which could equate with loose fitting between plug and socket contacts. It's worth your while to eliminate that as the cause of your problems, if only because it is a sneaky and unanticipated failure.

de

 

[LCGuy]

Thats really quite interesting, equill. Yes, i am still using the original transparent Apple power cable with it. I might have to have a look at the plug and check that its in good condition. Just like yours, mine is a 9.2.2/10.2.8 machine. Either way, thank you for the advice, definitely something that I'll check out, and that I never thought of before.

For the record - you've had your iMac 500 since 1983? Wow, must have been a *really* early prototype! Did you get it from these guys by any chance?

 

[equill]

I haven't a clue where 1983 came from (other than from my fingers), but 2003 would make a good alternative with a little more credibility.

As for the prototype status of the iMac, it could even be accorded the accolade of visionary ... Move over, Macintosh.

de