Can I change PRAM battery of my iMac G3 DV400 SE myself?

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Level 1

8 points

Can I change PRAM battery of my iMac G3 DV400 SE myself?

Hello

I need to change the PRAM battery of my iMac G3 DV400 SE as it hasn't been starting up for a few weeks now. I am posting here to get some safety advise, both to avoid electrocution myself and to avoid damaging the electronics. Please bear in mind I am a complete novice and a lay person. I have located the battery behind the RAM and Airport Card hatch - and I intend to change the battery through here rather than take apart the entire bottom half of the machine. Anyway, I have kept it unplugged for a few weeks. Now, do I need to get anti static gloves/ wrist strap, mat, etc? What tools do I need - for example tongs to pull out the battery or is it safe to just do it with bare hands? And how about clothing and shoe wear? Is a bed in a carpeted room OK? Or what sort of environment should I do this in? For that matter, should I do this myself or should it be handled by professionals?

Thank you.

iMac, Mac OS X (10.2.x) , Graphite iMac DV SE (400)

Posted on Feb 21, 2016 9:52 AM

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Answer 1

Best reply

Kenichi Watanabe

Level 8

41,572 points

Feb 22, 2016 3:29 AM in response to 3DMonkey

You've given this a lot of thought... 🙂 Anything you can reach through that opening is safe, as long as the iMac is powered off. The danger (high voltage) is at the back of the CRT, which Apple makes (by design) difficult to reach (unless you intentionally take the iMac apart beyond the "user level"). It's just a low-voltage battery, like changing the battery in a flashlight.

To avoid unlikely but possible damage to the Mac, you should discharge static electricity from your body. Working on a non-carpeted floor is better. If you are doing this on the kitchen table, touch a grounded metal surface, like the sink faucet.

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Answer 2

Allan Jones

Level 9

68,714 points

Feb 22, 2016 3:29 AM in response to 3DMonkey

The only thing I can add is that the battery is a bit hard to reach with your fingers through the RAM door. Unless you have very small fingers you may wish to find a non-conductive set of forceps, small pliers or similar gripping device.

Apple learned their lesson and, when they developed the eMac, they used a larger door and a battery position that could be reached without tools.

The only time I changed the PRAM battery in a G3 I was also upgrading the hard drive, so did not have to find a proper gripping tool because I had the bottom cover off. Kenichi is right--the area when the battery resides is well-shielded from the high-voltage section. It's OK to go through the bottom cover if you cannot change the battery through the RAM door, with the cautions you and Kenichi have already enumnerated.

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Answer 3

Jeff

Level 6

12,058 points

Feb 21, 2016 11:52 AM in response to 3DMonkey

Of equal importance is observing the orientation of the battery when you remove and reinstall one, in terms of the polarity. You might forget it, if the battery slips from your fingertips and rolls about the motherboard. The end of the battery closest to the Airport card vertical support frame and memory access door is the ➕ tip.

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Answer 4

3DMonkey Author

Level 1

8 points

Feb 22, 2016 3:36 AM in response to 3DMonkey

Thank you all for your advise, I appreciate it very much.

Can you also suggest a safe anti static container for placing the RAM sticks and airport card while I take them out to access the PRAM battery?

Thank you again.

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Answer 5

Feb 22, 2016 11:06 AM in response to 3DMonkey

If it's necessary to remove those other components, just place them on the table. There is no need for a container, unless you plan to store them away for a while.

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Answer 6

3DMonkey Author

Level 1

8 points

Feb 24, 2016 9:26 AM in response to Kenichi Watanabe

Thank you Kenichi, I feel confident now.

I've ordered the anti static gloves (just incase) and some adjustable tongs as per Allan's suggestion - thank you also.

I've got the polarity worked out too - this is the exact battery that is currently installed:

http://ecx.images-amazon.com/images/I/21c48azg4WL.jpg

http://www.computer-answers.ca/wp-content/uploads/2011/07/PRAM_batteries_3-6_4-5 V.jpg

So I've worked out the polarity from the picture also (the flat (green end) bottom is ➖).

Thank you too Jeff.

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Answer 7

3DMonkey Author

Level 1

8 points

Mar 5, 2016 8:37 AM in response to 3DMonkey

Hello

This is an update. I have managed to change the PRAM battery - it wasn't difficult, just a bit fiddly. I tried using the flex tongs but found it rather difficult and the spring also sometimes just 'snaps' causing the battery to be ejected out at high speed. So I just did it with my fingers - wearing the static gloves ofcourse, which is actually not as hard as I thought but you need both hands. My apologies about one thing though (my memory is not what it used to be lol) - the battery that was already installed was this version:

http://www.usedmac.com/catalog/images/922-4028.jpg

And therefore the ➕ end is the green end which is what faces towards the access hatch. .

Anyway, having changed the battery, I attempted to boot the machine. However, it still doesn't turn on. The power button turns green and then just dies - so I kept it plugged in for about a day and a half - however the result is the same. So my next attempt will be to reset the PMU.

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Answer 8

3DMonkey Author

Level 1

8 points

May 6, 2016 1:02 PM in response to 3DMonkey

Good news - as of around 20:00 hours GMT, the iMac has booted back to life.

There are still a few teething problems - it doesn't recognise the external firewire drive with Tiger loaded - it is currently running Jaguar and can also be booted in to OS9. Also it is not recognising the Airport card. But I hope these things will rectify themselves as the iMac has done so far.

Since I changed the PRAM battery the first time around, I only pressed the PRAM reset button later - then left it plugged in to the mains - and after about two months, it has come back to life. Oh - I also had to manually enter the correct date and time - it had gone back to 1970. Any way, will be grateful for any suggestions to rectify the remaining issues. Thanks again.

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Answer 9

3DMonkey Author

Level 1

8 points

May 7, 2016 12:57 PM in response to 3DMonkey

Update - I have solved the Firewire problem by turning off the power of both the iMac and the external Firewire Hard Drive, then unplugging both from the mains for ten minutes - after which I plugged both back in to the mains and powered up both units. This did the trick. I can boot back in to Tiger again. Tomorrow I will sort out the Airport card - I think it just needs to be reattached more firmly. Thanks again.

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Answer 10

3DMonkey Author

Level 1

8 points

May 8, 2016 9:56 AM in response to 3DMonkey

More good news - I have solved the Airport card issue. As per my research of the internet - I just reattached the Airport card more firmly - it actually clicks on each end when it is properly attached. So now the iMac G3 400 DV SE is back to full health. I am going to consider whether it is worth investing in additional RAM to take it up to a Gig (it's got about 640MBs at the moment) - or should I sell it while there is time lol (although parting will be so hard, I've had this from new for 16 years - not to mention it is not worth a lot in the real world - but is the space worth it today?). Web surfing with TenFourFox is avery clunky (forget Youtube lol) but I love having iTunes 9.1 streaming Radio again - as well as playing my own stuff. Any way, thanks for everyones input and I hope this info helps anyone else that suddenly finds their G3 iMac not powering up - DO NOT CANIBALISE or dispose of in any way - these things are still gems.

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