G3 iMacs

Posted by: Jias

G3 iMacs - 02/25/05 03:12 PM

So I came into possesion of a pair of G3 iMacs this last week. Sweet, they're kind of funky machines, maybe not the most powerful, but for around the house... and they were free. How can you argue with that?

So here's the problem - only one of them (the Indigo one) is booting right now. I updated firmware, put a 40gig drive in it and partitioned it for two installs: 9.2, and 10.3 (just cloned my laptop system over using Mike Bombich's Carbon Copy Cloner - totally great). Sweet. It all works fine. Even swapped out the original optical drive (just a CD-ROM) with the Graphite one that isn't working (which is a CD-RW). Everything is going great, except I can't get the VGA out to work. I connect my old PC monitor to it, turn it on, and nothing. It goes into it's little "check cable" thing that CTRs do when they aren't connected. Anyone know anything about this? Is the VGA out just shot, or is it something to be repaired? This is a 400MHz iMac, Summer 2000 I think.

As for the other one, it gives me the three beeps - meaning (to the best of my knowledge after Googling and digging around) "No RAM banks passed memory testing", or something similar. Any idea as to what I can do to get this one running too? It's a Graphite 600 MHz machine, early 2001, best as I can tell. I know it's not bad RAM, since the RAM cards I tried in it all work just fine in the other iMac, as well as my HP SuSE/XP machine. I'd love to get this one working too, since it's obviously a bit faster, and one of them will go to a buddy of mine (to replace his Win98 Dell that's dying - needs a total re-install and was recently dropped about 3 feet onto asphalt... it's not doing so good) if I get them both running.

Any thoughts or tips would be greatly appreciated.

Posted by: maestro

Re:G3 iMacs - 02/25/05 03:38 PM

My question is: Is it the right Ram? They require the same speed of Ram, but maybe it has something to do with timing? Did you try both Ram slots? Hope you work it out, a the most you can take it to an Apple dealer and have them check it.
Posted by: oojacoboo

Re:G3 iMacs - 02/25/05 04:40 PM

on the first one I would double check to see that all the firmware is up to date. Honestly, I would be satisfied with a free computer that only has a VGA out problem.

As for the second, I would fumble around with the RAM a little more. Maybe something isn't right. What about resetting the logic board and trying a few other illogical tricks, you never know, sometimes the strangest things fix problems such as that. What happens other than the three beeps on a boot? Does the CRT turn on? Do you see anything on the screen?
Posted by: Jias

Re:G3 iMacs - 02/25/05 04:56 PM

Yeah, I tried both slots with 4 different RAM cards - 2 different 128s, a 256 and a 64 (which isn't enough for OSX, but it is for openfirmware, and even OS9). Any combination of these cards works just like you think it should in the Indigo iMac, but the Graphite beeps no matter which ones are in it, or which slot they're in.

I know a bit of the history of the machine, and I know the 256 card used to work in it (the card continues to work in the Indigo). It was used as an office machine, to run Mail, iCal, and Safari, basically. It stopped working one day, and when no one knew how to fix it, they got ahold of a G4 from elsewhere and went with that, and sent this one to the curb. I've got a bit more time and patience to deal with it (they needed a machine that worked right away) than they did, so here I am.

I just don't know if this is something that's a fairly easy repair, or something that needs to get replaced (the RAM slots? the whole motherboard?). Just hoping someone has some kind of an idea or a lead as to what I can do with it.

Posted by: Jias

Re:G3 iMacs - 02/25/05 05:01 PM

the Indigo - firmware is updated, and yeah, it's a minor issue, but I'd like to get it to work if I can. If not, it's not like it's a deal-killer or anything. The VGA out only mirrors anyhow, but it'd be cool to get working.

The second... you know, I'm at work right now, and I'll post again when I get to play with it some more - I THINK the CRT powers up, but it's just black, since the machine can't boot and send it any information. Beyond the three beeps (and the subsiquent flashing of the power light) nothing happens with it.

I'll play with the logic board, and try re-seating what I can.

You know of any good take-aparts for these things? I'm hoping to know where things are a little bit better before I undertake the rather daunting task of taking it all apart.

Posted by: whitlock

Re:G3 iMacs - 02/25/05 05:17 PM

If you can actually hear the CRT turn on, it should be powering on, and the beeps are indicative of the issue. Three beeps = Bad RAM (RAM did not pass checksum). I made this handy little chart for ya!

1 beep = No RAM
2 beeps = Incompatable RAM
3 beeps = RAM did not pass checksum (bad RAM)
4 beeps = Bad checksum on the remainder of the boot ROM (boots, but can tell you whats up)
5 beeps = ROM on the board did not pass checksum (ROM boot block)

Reseat the RAM, reset the PMU on the logic board, and see if that works.
Posted by: maestro

Re:G3 iMacs - 02/25/05 08:52 PM

Whitlock is always one to have the great info. If anyone can help you, he can. By the way,
did you check the battery? Just a thought.
Posted by: Jias

Re:G3 iMacs - 02/25/05 09:21 PM

I'm aware that three beeps means roughly that - I've seen different wordings of the meanings, depending on the hardware that it is referring to. But essentially it means either:
a) bad RAM (which feel I can rule out as I know the RAM works in several other machines, including another G3 iMac); or
b) bad RAM slots (which is a definition that I have heard for the three beeps reffering to
a couple different kinds of G3s)

That's my take on it, anyhow. But since I don't have the original manuals for the iMacs, I can't say for sure.

Posted by: Jias

Re:G3 iMacs - 02/25/05 09:22 PM

maestro wrote:
Whitlock is always one to have the great info. If anyone can help you, he can. By the way,
did you check the battery? Just a thought.

yeah, thanks. I've been lurking for a while now, so I know he knows his stuff. smile
Posted by: KnifeLord

Re:G3 iMacs - 02/25/05 09:42 PM

Have you tryed just changing that logic board out with the other G3? I am not sure, but is one the newer clear toped iMac and the other the old style non-see through backing, or both the older style non-see through? If they are both the older style, you might just try changing out mother-boards and see if they both boot up, or if the (?) 'bad-logicboard' still doesnt boot up. That way you can for sure decide if the logic board works, or if it just is wired wrong/powers wrong. I know the current thought is that it is a bad RAM connector, but it's possible that it had a power surge and just needed to be moved around/reset.


(PS: But first I would start reseting the P-Ram and PMU much easier!)
Posted by: oojacoboo

Re:G3 iMacs - 02/25/05 11:28 PM

if the ram works in the other system and doesn't in the current one, your guess can be pretty strong that there is something wrong with the RAM slots or the logic board.

I think that you need to take the first step in resetting everything, the logic board, remove the battery, remove the ram and put it back, etc. If all of this doesn't work, then you may have bad logic board in the system. sick