Replacing the CMOS battery

Hi everyone.
I replaced the CMOS battery to one of my computers and now it won't boot up at all. Before I replaced it, when I would start up my machine, it would show the Emachine logo, then it would show the beginning boot up sequence really fast, then it would shut down at that point. I knew it was the battery because it would get past that a couple times. So I took the battery out, went to the store, and found one like it. I then put in the new battery, then pluged in my monitor, keyboard, and mouse then turned it on. When I turned it on, nothing at all came on. Am I missing something? Was I supposed to reset something and didn't? Anything would help. Thanks ahead of time.

What kind of motherboard is it?

Well...........

1. Get someone with a multimeter or battery tester to check that the battery is OK............you can actually buy a dud straight off the shelf :(

2. Is it exactly the same volts and amps as specified for your machine

3. Wipe the surfaces with alcohol and wear gloves or use tissue when inserting it.........make sure that it is firmly seated and that any retaining clips/springs are in place.

4. Sorry about this: is it THE RIGHT WAY UP (are you observing the correct polarity) Usually the flat bit with the number faces up.

5. I hope it wasn't one that you have to solder to the MoBo :eek:

Please keep us posted :)

Reset the CMOS data too by crossing the jumper for it. It might not auto-load the default values.

Ok. To what nihil said, I dont know if the battery is ok, I bought two so I'll try the other one. It is the exact same volts and amps as the one before it. It is inserted firmly and the right way up, I was paying real close attention to this. And it is not soldered on, thank god.

Now to what The3ntropy said, I haven't a clue how to reset the CMOS. I remember reading something about doing that, but it didn't say how to.
Thanks.

Update: I don't think that it is the battery. I just replaced it with the other one and still nothing.

When you power up do you get any noise, any lights, any beeps from the machine? What does the monitor do?

Do you still have the old battery that you can try it with?

What make & model of machine is it, and about how old?

What is the version and supplier of the BIOS?

This does not sound like a simple battery problem to me

Cheers

Well, when I power it up, the fan for my video card and for the processor go on, and there is a little red LED light that turns on. When the computer is on before this problem, there were two light on the outside that were on, it was this big button (power button) that had a green light around it when it was powered on and then this little yellow light that was on whenever the computer was doing anything. Now the only light that is on is that yellow one, the green one won't even flicker. The monitor isn't even flickering or anything. I've pluged it into my video card and the original video port and nothing is happening with either of them. I tryed the old battery and it isn't working anymore. The make and model of the machine i guess would be an Emachine T2080. It is about 2 or 3 years old.

Oh yeah. There was a little sticker on the bottom of the case that had a diagram of the jumpers. One of them was for the CMOS. It said that 1 and 2 is Normal, and when in 2 and 3 is clear. I moved it to the clear then turned it on and nothing. Then I moved it back and still nothing.

Usually, CMOS battery issues can be assumed when the time on your computer mysteriously resets itself to the default time some time after you've disconnected the power cable.


[strike]So from your description, it wasn't the CMOS battery that was the problem. It could be your computer's PSU (Power Supply Unit) that has given out. It would explain why nothing powers on. And the failure after you replaced the battery could be purely concidental.


Have you upgraded things on your computer like the Video Card? Or added more Hard Drives?[/strike]


Can you check to make sure your power button connects to something on your computer? Maybe you disconnected it from the motherboard so it doesn't go where it is supposed to in order to turn the computer on?

That is strange, I would expect the monitor to show some kind of self-diagnostic or no connection message............try it without it being connected to the computer....

Cheers

I added a video card last December, but it still worked fine. As far as I can see, everything is still conndected. The only thing that I have touched is the battery and what the diagram says is the CMOS jumpers.

What do you mean nihil? I have done it without the monitor pluged in to. When ever I turn on the monitor by itself it says "no signal detected".

OK Madseel,

Sorry for the gap................slight local electrical problem :eek: .............It does not sound like "just" a battery problem...........give me a little while to think it through and I will get back to you tomorrow.

Cheers

uhhh.. keep in mind here that when you go to reset the bios via the jumper..

1. you must unplug the AC cord from the power supply or turn off the switch on the supply.
(if you don't, it most likely won't work as power is still avail to the mobo, it's in sort of a standby mode)

2. move the jumper to reset , then move it back to the normal position
( you didn't say if you did that)

AFAIK.. most mobo's will power on and work even without a battery in the socket. it's just that you won't be able to save the values.. you might have to reflash the bios if things don't seem to be getting any better. I really hate to suggest reflashing unless it's the only thing left to try.

now what is the motherboard type/model ? did I miss that in the previous posts ?

edit : yeah.. you said an emachine and model of the emachine but that's not what we really need.. you need to look at the motherboard and read the labels on it.. emachines might use various vendors for the mobos.. I don't really know..

typically, if one had a bios string.. (of which you probably won't be able to give us) that would point out the bios type ,mobo manufacturer.. and would lead to a certain mobo model. maybe see if you can read what printed in the bios chip.. it should be located fairly close to where the battery and jumper is.. it'll usually have a sticker on it.. with a date code and maybe bios revision.

Ok. I found the specs to my mother board. Here they are.
http://www.ecsusa.com/products/l7vmm.html

I'm not sure but could it possibly be that i shorted the mother board?

Hmmm,

I don't think you have damaged the mobo, as it is generally quite hard to do.

It sounds like something has failed. If you still have the old battery get someone to test it with a meter, as well as one of the new ones..............it might not have been the battery at all.

I don't suppose you noticed if the system clock was losing time before this happened, or would show the wrong date?

Quote:

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Now the only light that is on is that yellow one, the green one won't even flicker.

---

That suggests to me that the machine is not powering up properly. The little yellow light is probably the powers supply or hard drive. Check that all connections to the power supply are firm and that all wires are firmly connected to the MoBo. That green light should come on, even without a CMOS battery.

If the batteries are OK and you have reset the BIOS properly then it looks like another fault altogether.

Check to see if there is a little fuse (clear glass) behind the switch (the big button with the green light), is it "black and horrible". If you have the manual for the machine, you might find out what the lights are for...........did the light around the big button use to flicker when the machine was running?

Other possible causes:

1. Failing power supply
2. Failing RAM
3. Dead hard drive

If you can check those batteries and what the lights are for it could get us closer

:)

The clock thing I did notice. It was losing time. After about every week it lost about 10 to 15 minutes.

If I were to turn on the computer even with a dead hard drive, shouldn't it boot up at least to a certain point? Also, would it effect it if the battery was out for an hour or too?

I'll check the connections right now along with that fuse thing. The only thing i touched though was that stupid battery.

Well 10 minutes in a week means that it still had some power in it, unless you leave your machine on for extended periods, like overnight.

As for the HDD, it is hard to predict exact behaviour when a component starts to fail. Particularly if you have "fast boot" enabled in your BIOS.

Taking the battery out is one way of clearing your CMOS memory.

I don't know your machine so I cannot be sure, but usually the light around the power switch means that the system is switched on.

Depending on your machine, it might have a rocker switch at the back near the power cable socket. When you turn this on, it puts the machine into a "standby" mode so power is getting to things like fans and the Hard Drive, and you may well see some lights come on.

It is the power switch at the front that actually boots the machine.

Cheers

Yeah. What you said about the light in the front, that is when it is powered on. I do leave my computer on over night and for extended periods of time.

I have checked that everything is plugged in compleatly and it seems like they all are. I am not able to see the fuse thing as I don't know how to get to that, but would that cause the whole computer not to start up or anything?

Last, that rocker switch in the back near the power socket, is it usually red? There is something back there but I haven't touched it. That red switch thing in the back has a number 115 on it, but the 115 looks like it was pushed in the middle a little.

One more thing, I was looking at the jumper diagram and it said there is one for "BIOS PLASH". This is enabled. Should I set it to disabled then back to enabled or just leave it alone?

Right,

Leaving the machine on for long periods will hide the fact that the battery is run down because the clock is running off the mains power during those times.

There may not be a fuse on your I/O button (switch) some do and some don't. Now that light SHOULD come on. If it does not, then there is a problem with the switch, the light has blown (unusual for an LED), or there is a problem with the power supply.

If there is no rocker switch (like a modern light switch) at the back. the machine is getting standby power as soon as the mains electricity is turned on.

The little red switch with the numbers on it tells the power supply what current your mains is usually they go 115v and 230v. The switch is not easy to move, so you won't have done it by accident. I think that you have mains voltage of 110-120v where you are. The only problem is if you set it to 115 over here where we have 240v mains current.........that would fry it.

It sounds to me like your I/O switch is broken...............with the case off can you trigger it manually or poke something NON-CONDUCTIVE into the hole and see if you can get it to start.

Basically a cleared CMOS will not prevent the power on light from coming on. However, NO POWER will prevent the CMOS from being reset.

Now, some case/motherboard configurations are a bit difficult to put back in the right alignment, which is why I would like you to try to activate the switch with the case off. I have had several experiences of putting the case back on and the I/O switch didn't work.

I hope that is the problem, as it is easy to fix.

With the case off, check for any noise when you push the button. You should hear the HDD start to spin up, also you should have a brief flickering of lights on the floppy drive (if there is one) the CD drive and the keyboard.

If you don't get these I strongly suspect that the machine is not booting at all, as opposed to getting part way then failing.

EDIT: Please leave the BIOS Flash jumper alone, if it is set to "ON"

I am not able to find another switch to power it on but I will look harder. When I do press the power button, the hard drive does sound like it is spining, but the lights on the floppy drive and CD drive and keyboard are not flickering or anything.

OK,

I understand it a bit better now, when you take the case off you do not remove the front...............don't worry there won't be another button.

Now, let's try this:

Push the power button in and HOLD IT IN like for a few minutes. With any luck you should see some of the other lights.

If by some stroke of luck it starts to boot, let it (keep the button pressed in all the time) then <start> and <shutdown> with your mouse. Then let go of the button.

These switches a spring loaded and the little clasp that holds them in the on position sometimes breaks or wears down.

Sorry I took so long, I was eating dinner.

I tryed this pushing the button and holding it, but there is no power on until I let go of the button. Then when I hold it after that, it is shutting down.

Hi I am back............I guess I am between 5 and 8 hours ahead of you in the timezones so I sleep at different times :)

If it is a "big" power on button, I am guessing that it goes in a fair bit then pops back out? Try pushing the button in all the way then very gradually let it back out again. Keep an eye on the green light to see if it flickers or comes on.

I guess that this is the point where I would get my multitest meter and check the outlets from the power supply.

I would put a hard drive with a pre-loaded OS into the machine, or attach the current hard drive to another machine as slave and run diagnostics on it.

I would take out the memory strips and insert some that I know work (in another machine)

I would get my desoldering gun and detach the two wires at the back of the I/O switch then twist and tape them together (bypassing the switch)

If it does not boot after that I would say the motherboard was damaged.

I do not think that it is the CMOS, as removing the battery would only clear any boot password and reset other values to the defaults. This would be the clock/calendar and possibly one or two other system settings.

The boot sequence is roughly:

Check memory
Check extended memory
Look for keyboard
Look for mouse
Look for hard drive
Look for floppy
Look for optical devices (ZIP, CD, DVD)

Now, as you are NOT getting any flickering lights on the keyboard, floppy or CD, I don't think that you are getting very far into the boot cycle.

If you have some compatible memory (check the specifications carefully) you might try removing the existing memory and trying with that. If not at least take out the memory sticks, clean the contacts and make sure that they are firmly re-seated.

A question: Does the yellow light at the front come on when you turn the power on at the mains, or when you press the big start button?

Cheers

I did what you said about the button, but when I did that the same thing happened as the other times, nothing. I cannot try that other stuff, but maybe the slave drive diagnostic, as I do not have any spare parts I can try it with.
An answer to your question about the yellow light is that it would turn on when I powered it up. I think that it would flicker when the hard drive was being writen to.
One more thing, I don't know if this is relevant to this problem or the cmos battery, but before I took out the battery, I would boot the machine. It would boot to where I chose to go into Linux, or Windows. When I chose windows, the machine would reset most of the time, or it would boot a little, then reset.
Sorry for this delay, I was kinda busy today so I just barley had a chance to test this out.

I'm thinking that this issue has nothing to do with you changing your CMOS battery.

We might want to bring to life again the chance that this is your power supply. Disconnect power from the parts you don't need. Make sure the computer is off, and then disconnect the power connectors to your CD-ROM drives, and extra Hard Drives. Just keep power connected to your Hard Drive that has your OS Loader and Operating System on it. Also, if you have onboard video, take the other video card out and use your computer's "onboard" video card. This should reduce the amount of power your computer's parts consume during boot-up (because they are disconnected and don't boot up) so you might be able to get your computer started.

DO NOT PLUG STUFF IN TO YOUR COMPUTER AFTER IT IS ON! You must remember to power off your computer before plugging hard drives back in, etc. Just a warning. If you can get it started with nothing connected, you may need to look at buying a new power supply, because it could be that your current one has reached the end of its days. A weak power supply can make a computer reset itself when you are booting it up. It can show problems at other times, but in our case booting up is the biggest factor.

If it doesn't work, either your power supply is too dead to power up with very few things, or the problem could be something else... And this has nothing to do with the CMOS battery, BTW...purely concidental...