iMac G3 dead after replacing PRAM battery

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Level 1

4 points

iMac G3 dead after replacing PRAM battery

Hello everyone! I'm new here, and i don't know if it's required an initiation ritual or something like that (and sorry if my english is not extended).

After years of wandering an iMac G3 (is well placed in my memories, i surfed on internet for the first time with this computer back in my school), finally i got one. A Bondi Blue, from 1998, CD tray-loader, 233 mhz, revision “B”, OS 9.2. When i arrived home, i plugged it, and worked perfectly. I used it for days, installing new software, replacing some data and erasing another from the last user. Then, i noticed that the PRAM battery was dead (everytime i turned up, the data was back to 1957).

So i unplugged it, opened, cleaned some external parts, and replaced the battery. Easy. The problem arrived in time, when i managed to assemble everything again. I was very cautious, doing it on my bed, slow and without forcing the parts. But when i plugged it again, the computer was dead. I press the power button several times, but nothing. No answer, no light, no turn up. Nothing. I just hear the quiet buzzing of the CRT static electricity when i plug it into the wall, but nothing more. I changed the power cord, waited some minutes plugged, but... the iMac doesn't turn on.

I have disassembled it again (only the transparent part, where the motherboard is), did some test with the old PRAM battery, checking the internal cables, connectors, and everything seems OK (according to my inexperienced eyes). The only thing that comes from the iMac is the silent buzzing of the CRT when i plugged it. No beeps, no cracks, no other sound. Only the CRT and me, on the bed.

I'd searched about this problem on internet, but the only thing that turned up is an old post with a closer case, but the threat ended without any solution. I'm really scared because i heard that this problem means that the computer doesn't have any solution. THE BONDI BLUE HAS PASSED AWAY. But i want to try everything i (and my wallet) can do, for keeping the hope. I need to fix THIS computer (i don't want to buy or get another one).

I guess what i'm asking is: BONDI BLUE IMAC WON'T TURN ON AGAIN AFTER REPLACING PRAM BATTERY. WHAT DO. HELP.

Literally any suggestions or advice are appreciated. Thanks, thanks, thanks.

Rick

iMac, iOS 9.2, G3

Posted on Apr 22, 2017 5:37 AM

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Answer 1

K Shaffer

Level 8

36,016 points

Apr 24, 2017 1:25 AM in response to sad_OFFICE

Most Mac computers had a means of resetting the power chip, and the reset

method for the early iMac G3 may be archived in some old article online; or

in a PDF Service Manual or some other archive.

Examples of reset methods/models appears in this site page ~ but no iMac G3:

http://thexlab.com/faqs/resetpmchip.html

The reset may be necessary to flush bad stored memory in the chip used to

retain these background information such as Time/Date, & other system data.

These power management chips have used various names across build models:

SMC: Systems Management Controller.
SMU: Systems Management Unit.
PMU: Power Management Unit.
CUDA: Capacitive Unit Discharge ASIC (Application-Specific Integrated Circuit).

There is an archived vintage manual that may or may not be of help in your attempt

to restore older iMacG3 (circa 2001/Summer+ models) in PDF from the following link;

this may load in browser -- but should be downloadable -- as archive for offline use.

• iMac (Summer 2001) manual - link service source (content updated in 2005, July.)

PMU Reset (button) is on logic board. See manual for general access information;

here are two page/images from such a service guide...

Image of location on logic board of PMU reset button most iMacG3 models;

your model will not have the ATI Graphic chip shown. ~ There may be better

images+instructions online at powerbookmedic.com or iFixit.com sites

So there are some ideas & different resources to be on the look-out in this matter.

Hopefully you can make the unit awaken, but there is a chance the 'power analog

video board' may have toasted.

Good luck & happy computing! 🙂

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Answer 2

sad_OFFICE Author

Level 1

4 points

May 11, 2017 7:36 AM in response to sad_OFFICE

Hello guys, sorry for the delay. At the moment i don't know if i must cry or laugh!

After all your helpfully tips, advices, comments and posts (thank you kindly) i decided to wait because at that time i had a lot of work, and this machine needed a bunch of patience to start with. So today, i took up the iMac, plugged in the motherboard, and the computer STARTED UP. WHAT THE ****?! I didn't do anything new, the iMac was on my desk, unplugged, all this time, as when i wrote the first post. It's like if the G3 fixed it by itself. WHAT?!

The computer works fine, like the old times, now with the new PRAM battery. I checked everything and it's okay. I don't know how to explain this, it looks like a person who has an ill and remained in bed some time till the virus is completely gone. Maybe all this time unplugged, something happened with the electricity, i mean; I guess that the problem came from the new battery.

So, i think this post is closed, solved, and fixed by itself. What a thing!

Thanks guys for your time, your knowledge, and good purposes, you are such a good people.

Rick.

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Answer 3

Jan Hedlund

Level 7

24,235 points

Apr 24, 2017 2:24 PM in response to sad_OFFICE

Hello,

Normally, merely replacing the logic board battery (https://manuals.info.apple.com/en_US/iMacG3_originalInstallGuide.PDF) should not lead to another problem. However, we cannot rule out that even a careful turning and opening of the computer has affected, for example, an already bad/cracked solder joint or a weak cable connection somewhere. This could possibly be (on the way to or) in the closed analogue/power section of the iMac. That section is closed for a reason: There are high voltages inside. Dangerous charges can remain in the CRT and capacitors for a long time after the computer has been switched off and disconnected from the mains. Repair work here is for qualified personnel only.

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Answer 4

sad_OFFICE Author

Level 1

4 points

Apr 23, 2017 3:51 AM in response to Jan Hedlund

Thank you so much, Jan.

I still have hope for thinking that the problem is a bad connection or a bad solder joint. Although, i can't do anything by myself, because i don't want to breathe one's last with the iMac under my arm. Today, i opened the fan in order to have an eye inside, maybe looking for a cable unplugged. But through the narrow angle that i could see, everything is in order.

Thank you kindly, any advice, question or comment will be welcome.

Rick.

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Answer 5

Jan Hedlund

Level 7

24,235 points

Apr 24, 2017 2:24 PM in response to sad_OFFICE

Hi Rick,

In a "no power" situation, service personnel would typically start by looking for adequate voltages on or near the logic board. For this, a multimeter can be used (and one would have to know what to look for). If nothing there, the search would continue into the closed analogue/power section. Any troubleshooting in the latter area is very dangerous, so you are right in not going there. You can compare this area to an old CRT TV set. Experienced TV technicians are extremely careful when working near high-voltage parts and filter capacitors (TVs and some monitors can also have a "live" chassis, making it even more dangerous).

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