Question about Acer Extensa 390CX Notebook

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How do I replace the CMO

My son was just given an Acer Extensa 390C Laptop but get error "CMOS Battery Bad" when booting up and does not keep time. I downloaded the Service Manual and have the internals exposed, but tells me nothing about replacing the CMOS battery. How do I replace the battery? Thanks!

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CMOS battery is that one, which keeps the bios settings and the time. That is now surely is not charging up and it has to be replaced. That is just like a coin. CMOS battery of desktops are easy for desktops, but i am not sure, where it is ( on mainboard though) exactly and the laptop should be opened. please take it to a repair center if you are not willing to open it yourself. its not a huge problem and do not worry.


Posted on Apr 18, 2009


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Posted on Jan 02, 2017


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Cmos battery

Replace an Acer Extensa CMOS Battery
CMOS batteries allow you to store basic settings on your laptop.
If you notice certain features on your computer do not operate correctly, such as the computer clock, you may have to replace your CMOS battery.
This battery sits on the interior portion of your machine and measures about the size of a dime.
If you have a screw driver and know how to work with your hands, you can replace the CMOS battery on your Acer Extensa computer.

Open the screen of your laptop until you can view your keyboard clearly.
Find the bar that consists of plastic on the upper portion of your keyboard.
Place your screwdriver on one end of this bar and slowly ease it up until you can grab its edge with your finger.

Pull the opposite side of the bar in the upward direction with your screwdriver.
Then, ease out the whole bar.

Take out the screws on the side portion of your keyboard.
Pull your laptop keyboard upward and put it on a soft surface such as a bed or pillow.

Take out the four screws from the steel plate, which covers the motherboard of your computer, and take off this plate.
This allows you to view the CMOS battery, which sits on the lower right portion of your motherboard.

Pull the CMOS battery up from the motherboard and take it off.
Insert a new CMOS battery, which you can buy at a local computer store.
Put the parts of your computer back in the same manner as you took them off.

May 26, 2013 | Acer Extensa 5620-4020 Notebook

1 Answer

Acer extensa 4220 will only boot without cmos battery?

OK, wait just a minute. You're telling me that you took the laptop apart to get to the CMOS Battery (which is on the motherboard), put it back together and have been doing this process with the cmos battery in and out? Are you sure you don't mean the battery that is on the bottom of the laptop?

If it boots with the cmos battery out that means you have to go into setup and set the date and time and possibly some other parameters every time because that little batter controls the computer's memory.

Mar 22, 2012 | Computers & Internet

1 Answer



If you have forgot BIOS password then you have to reset CMOS jumper setting. Please follow the below steps: Open the Laptop back panel. Locate the CMOS battery, remove it & then with the help of a screw driver keep on pressing the terminal inside it and turn ON the computer for 10 secs and Turn Off (make sure you keep on pressing the terminal with a screwdriver while turning ON). It will short the BIOS setting. Now, fix the CMOS battery & restart the computer. This will take care of the issue.

Thanks and regards,

Dec 13, 2010 | Acer Extensa 5620 Notebook PC

1 Answer

I have a bios password in my acer extensa 522u and i forgot it. how can i remove that password?

To reset the BIOS read the information from this link.

In case of your Acer Extensa laptop the easiest method would be using software from Hiren's Boot CD as it's pretty hard to open it up and reach for the CMOS battery or the jumper.

Nov 08, 2010 | Acer Extensa 500T Notebook

1 Answer

Extensa 5220 can i force boot to cd outside of the bios? IE: key stroke.I have removed the cmos battery but am unable too clear the BIOS password my S**thead nephew set up and with vista I can not reload...


To boot from CD, simply start your laptop and then press F12 immediately, and you will be given boot device options, with out having to get into your BIOS setup.

Thank you for using Fixya,

Feb 20, 2010 | Acer Extensa 5620 Notebook PC

2 Answers


Yes, you do have to take it apart. How do you know the cmos battery is bad? Is the time wrong all of the time??Does the BIOS default all the time??

Nov 09, 2007 | Acer Extensa 710TE Notebook

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