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Casio FX-991EX Battery Replacement

Introduction

The Casio FX-991EX can malfunction if the battery is discharged, even with solar power. Thankfully, replacing it is a simple job.

What you need

  1. Casio FX-991EX Battery Replacement, Remove the battery cover: step 1, image 1 of 2 Casio FX-991EX Battery Replacement, Remove the battery cover: step 1, image 2 of 2

    • Remove the battery cover's screw using a Philips #0 screwdriver.

    Edit

  2. Casio FX-991EX Battery Replacement, Remove the battery: step 2, image 1 of 2 Casio FX-991EX Battery Replacement, Remove the battery: step 2, image 2 of 2

    • Use a spudger to remove the battery using the gap to the right.

    • Don't use sharp objects that may cause harm or damage. The battery can be hard to pop out, but will do so. Dispose of a damaged battery via an e-waste collection site.

    Edit

  4. Casio FX-991EX Battery Replacement, Replace the battery: step 3, image 1 of 2 Casio FX-991EX Battery Replacement, Replace the battery: step 3, image 2 of 2

    • The FX-991EX uses a 1.5V LR44 battery.

    • Slot the new battery into the compartment. Ensure that the positive side (with writing) faces up...

    • And the negative side faces the calculator's screen.

    Edit

  5. Casio FX-991EX Battery Replacement, Screw the cover back on: step 4, image 1 of 1

    • Slot the battery cover back on and screw it down.

    Edit
Conclusion

If you need to reset the calculator after this, it's SHIFT+9 > 3 > =.

Otherwise, you're ready to crunch numbers again!

4 other people completed this guide.

Author

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FarmYard Gaming

Member since: 08/27/20

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4 Guide Comments

Just discovered during a lecture that my battery has become a spicy pillow - if you're leaving this in storage be careful and monitor it, lest it explode and/or warp the case irreparably.

FarmYard Gaming - Reply

Which size of screws

李生山 -

I found nothing in the slot. What can i do?

UTL Shaion - Reply

Do you see any wires connecting the battery to the circuit board? I don’t see any on mine. Both of ours may be fake lmao

Ivan Liu -

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