In any computer, the CMOS battery is a battery that powers a small memory chip that stores system BIOS settings. Sometimes the CMOS battery in an older laptop may need to be replaced. If the laptop asks you to set the system date and time every time you turn it on, chances are good that the battery needs to be replaced. Replacing the CMOS battery in a Toshiba Satellite model laptop is an in-depth process, but it is possible to do it yourself.
Prepare the laptop for disassembly. Unplug the AC adapter and remove the battery. Remove the screw securing the DVD drive and remove the drive.
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Remove the screws securing the wireless card cover, the memory card cover and the modem card cover. Remove all of the covers.
Remove the wireless card and the memory modules.
Remove the screws securing the bottom cover to the laptop and remove the bottom cover.
This should expose the heat sink and the screws holding it to the motherboard. Remove the heat sink and any exposed screws on the bottom of the computer.
Turn the laptop over and, using a guitar pick or something similar, lift the thin plastic strip running along the border of the keyboard. Depress the latches holding it to the keyboard assembly, and remove the strip.
There are two screws holding the keyboard to the computer. Remove the screws and disconnect the keyboard cable. Remove the keyboard.
This should expose several screws that hold the top cover to the base. Remove these screws, as well as the cables for the power button, touchpad and any other visible cables.
Remove the top cover, exposing the motherboard.
The CMOS battery, a small watch-style battery, should now be visible. Depending on the model of Toshiba, it will either be secured to the motherboard with a small battery clip, or it will be connected by two small cables. Working quickly, swap the battery for a new one. Moving quickly is necessary because in many models of computer, if the BIOS loses power for too long, it can lose all of its memorized settings, making powering on the computer a difficult, involved process.
Once the battery has been replaced, follow the above steps in reverse order to assemble your laptop.
Power on the laptop and set your system clock, if necessary.