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iMac G3/400 (slot-loading) startup issue

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Hey y'all, I have an indigo iMac G3 that's exhibiting a weird issue on startup.

I pulled it out of storage after being powered down for ~6 years and the PRAM battery was dead as a doornail - the startup would hang just after the chime with a black screen and the system was completely non-responsive. So I replaced the PRAM battery and now I'm having a different issue. The boot will still hang with no video output, but now the reset button works so I can press that and then immediately press and hold the interrupt button on the side to force it into open firmware. From there I get a display and can type mac-boot and all is well.

Any ideas? I'm tempted to just re-cap the analog board, but I've not worked around any CRT larger than a Macintosh Plus before.

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Probably goes without saying but have you tried the 3x PRAM zap trick?  Hold command, option, P and R right after the startup chime until you hear the startup chime again.


I mean it could be a hardware issue, could be caps, who knows, but the PRAM zap trick fixed a lot of weird stuff back when I did tech support on these when they were new.

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Before I go into some potential actions I would take I need to stress on the safety aspect of the CRT. I am glad you raised this concern. For this particular concern I will refer you to http://www.peachpit.com/articles/article.aspx?p=760956&seqNum=2


However, in terms of recapping, I do recommend it. If I am not mistaken, disassembly to the stage of freeing the logic board for a recap should not require high voltage components being exposed to the point of considering CRT safety procedures. I can't say this with confidence without confirming the iMac G3 model you have.

Apple's warrenty database will identify the type of Mac you have. Your serial number is securely sent, but you get only the name of your machine.



This site provides more information, but lacks security.

In terms of the irregular behavior on cold boot and the requirement to enter the open firmware prompt to eventually succeed to the desktop.


At the firmware prompt enter these lines, pressing Return after each one:





Maybe a firmware update is required, it wouldn't hurt to try:


Identifying the specific model will narrow down other possibilities.


Reset PRAM, this one I see has already been offered as I write this.

Report back if PRAM reset doesn't resolve the issue.

Edited by Alex

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So the pram trick didn't work, but curiously leaving it on in sleep mode overnight did. Although it also somehow rendered the hard disk unbootable and unreadable by the restore CD. A reformat and reinstall later and it's up and running just fine, or at least as fine as an 18 year old system with leaky caps (one of the small caps on the right side of the PAV board right by the front of the case has a trail of corrosion, and the big dude on that side is looking bulgy) and a blown right speaker can be.

The model, btw, is iMac DV (Summer 2000). I'm trying to decide whether it's worth it to recap the PAV board or just replace it with one of the refurb boards here: https://www.dvwarehouse.com/iMac--G3-Analog-Video-Board-c-584.html 

Which board would I need if I were to do that? Also, are there any preferred CF to IDE adapters/cards for these machines if I were to replace the hard disk, since it's obviously failing?

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I don't know which one of those boards would work, match part numbers for yours, I guess?  Although ~$150 is obscene.  Recap if you can do it is a LOT cheaper, or maybe just find another iMac that you can score a good/better analog board from?  They're still dirt cheap.


I'd probably hold off on hard drive replacement too until you've sorted out the analog board issue, it may be related to that.  If anything just replace it with another IDE hard drive.  Also common and cheap.  I'm not a huge fan of CF->IDE adapters, they do work, but in my experience CF cards die pretty quickly especially if you're writing to it a lot.  For example I had a PFSense server running off one and it died within a year...and that wasn't even being written to very often.

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On 9/12/2018 at 7:23 PM, corgski said:

and the big dude on that side is looking bulgy

Some large caps are bulgy looking. If you press on it you will notice that it doesn't resist. The only way to be sure is to remove it from the board and measure it with a multimeter.


Replace all other caps, especially if they are leaky.


150 or whatever for anything of this vintage is, in my opinion, too expensive. These machines were shipped in the millions. Granted, they are all old now and likely need new caps anyway. If you want to have fun, then this is part of the hobby, replacing caps can be fun and it's not that hard. If you buy all the caps for this machine it will be way cheaper than whatever that online store wants. It just takes time to desolder and solder on new caps.


I agree with Brett, just get an IDE drive, especially if you install any flavor of OS X on that machine. OS X is a busy OS and will press on the drive with much more tenacity than OS 9. That being said, I would still believe that you are not going to see any speed gains. If it is silence that you are after, a modern IDE drive at a low RPM (5400 or less) will be quieter albeit slows. The high RPM can yield performance at the cost of noise. Personally I would go for a simple IDE drive.


Just to go back to the analog board question, you can get a like for like, just read the model number off the board. You can share the model number with us as there may be more reliable revisions but I wouldn't bother, just recap it all but of course that takes time.

I hope this helps. I support whatever decision you take but the above is the personal path I would take. It is also more within the spirit of a circular economy.


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