View Full Version : Replace Lithium Battery in Power Mac 8100/100

03-02-2001, 02:54 PM
Can anyone give me some detailed instructions for replacing the lithium battery in Power Mac 8100/100AV? My computer won't boot up and from everything I've read in the forums suggest I have a bad battery. I have the box open, but I'm not sure how to remove the logic board to replace the battery. Any help appreciated.



03-02-2001, 05:18 PM
Well, I've never changed a battery on an 8100 but the mother board shouldn't have to come out. Here's a schematic, but it doesn't label the battery. Maybe someone that has done it will come along and point you to the battery in relation to something else in the schematic. It's about have the length of a AA battery in a plastic box with a squeeze-off cover.

03-02-2001, 05:20 PM
If your 8100 is arranged anything like my 8500 which shares the same case, then you may not need to take the logic board out.

I just changed the battery in my 8500 without doing so. In the 8500, the battery can be partially seen if you look across the insides of the box after the case is off. It's toward the very front of the machine, under the lower expansion bay.

After spotting it I was able to feel my way to it, remove the plastic retainer, and pry out the battery. Then I just reversed the process, feeling my way to install the new battery and replace the retainer. It helps if you are familiar with the basic structure of Apple's generic battery mount and have replaced a battery before. Naturally, you have to be careful to memorize which direction the battery should be oriented.

I hope you are as lucky as I was, because removing the logic board is a major headache on these boxes.

In any case, plan this carefully and don't go beyond what you feel comfortable with.

I had a fallback. I had already taken the blasted motherboard out a couple of times and knew I could if my quick fix failed.

Best of luck

03-02-2001, 05:26 PM
I have changed batteries in 8100s and 8500s a lot. Took the oportunity to remove the board and give it a good cleaning. Always had some dust bunnies hanging out inbetween the ram.


03-02-2001, 06:10 PM
Go here for a mobo pic http://www.sur-tech.com/cgi/page?item,m820-0588-a110 but get yourself oriented. In the pic that little black box to the left of the ram simm slots is the battery holder, but the pic I think is upside down, meaning top of the pic is bottom of the mobo. k

03-02-2001, 06:50 PM
Try using a dentist's mirror.

03-02-2001, 08:19 PM
Thanks guys...you're help was invaluable. I was able locate the battery really easily and pop it out and replace it with the new battery without even fooling with the logic board.

Problem is...The computer stills don't power up at all. All I hear is a low whistling sound as soon as I plug the power cord in to the ac outlet. It goes away when I unplug it. Nothing happens on boot up. Could it be the power supply???????

03-02-2001, 08:48 PM
Hey Jele,

Is it whistling "Taps"?--Har har

Do this really really quick 'cause whistling don't sound good: with the cover off so you can get to the space behind the drive bays, grab out an empty white plastic 4-pin Molex power connecter and stick the test leads from a Voltmeter in one outside socket and one inside socket (Ground). Power up. You should see +5V from one outside socket and +12V from the other outside socket (relative to one of the two inside Grounds). Power Down.

You will know if it's your power supply if you don't get these voltages. I suspect the sound you hear is the scream of tortured air in a dialectric created by an open circuit which should be closed (how'd I do Dookie?). This will heat up the situation real quick!

[This message has been edited by MacMikester (edited 02 March 2001).]

03-03-2001, 01:21 PM
When you say it does nothing, do you mean that the whole machine fails to power up, or does the green "on" light come on, and the drives whir, but the machine does not chime or boot?

This is not a 100% rule, but in general, if the machine does absolutely nothing when you try to power it on you have a power supply problem. If the drives and power light comes on, but the machine does not chime and does nothing but sit there and Whirrrr at you, then you have a motherboard problem.

Have you tried using the power on button on the upper back of the machine to power it on? The types of failure that look like a power supply failure, but aren't usually involve some failure in the keyboard/ADB bus (power on button not getting through) or a truly rare failure in the power on circuitry on the motherboard. There's a little circuit that shorts a couple of wires in the power supply to tell it to stay on.

The only time I've seen that power on circuitry fail was in my ancient IIci because some capacitors had leaked corrosive onto the circuit board and had eaten a wire. That's pretty unlikely on your 8100, so I'd say (if you've tried the power button on the back, and if it's a "quiet dead" with no drives going) that 95% it's the power supply.

You can sometimes get power supplies here: http://www.sur-tech.com for pretty affordable prices. He takes Paypal but not credit cards, so his payment options aren't the best, but his prices on used Mac parts are the best that I've seen.

But before you start replacing anything, make sure the power supply cable is plugged in all the way at both ends. The power supply cable between the power supply and motherboard unplugs at the motherboard end, but also at the power supply end, which makes it very unusual. Normally, the cable is an integral part of the power supply.

03-03-2001, 03:41 PM
I mean that the whole machine fails to power up..no lights...nothing.

03-03-2001, 07:44 PM
Try another keyboard and ADB cable. Sometimes the Power button on the keyboard will fail in such a position that the machine won't power up. You didn't add an extension cable to the ADB cable, did you? k

03-04-2001, 04:01 PM
Check that by starting with out ADB plugged in at all.

03-04-2001, 04:42 PM
Yes...I tried powering up the computer with the button on the back. Still no power. I'll bet it's the power supply.