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TI-84 Plus calculator support.

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Calculator randomly turning OFF

My calculator, out of nowhere started turning itself off randomly and resetting the RAM constantly. Sometimes I can turn it ON and use it for a few minute but other times if I just touch it or press any key it will immediately turn off. I have tried changing both batteries and didn’t work. What else should I do? Any idea of what might be?

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The LR44 is dead and needs to be replaced. You will need a #0 Phillps to change it on the TI-84. Once you remove the cover as the screw is captive, pop the old cell out with a flathead screwdriver and install a new one. Refer to this photo as to where it is replaced:

Block Image

In addition to that photo, this guide also shows how to replace it. The Plus Silver edition is the same thing as the Plus with removable faceplates.

After changing the coin cell out, check the batteries and how long they were installed. The TI-84 is power hungry (relative to a basic scientific calculator) and will be more picky about battery voltage. If you can switch, using NiMh cells will be better for your wallet and calculator, since it removes the risk of a leak entirely - but if it happens you’ll need to clean it up like an alkaline leak and replace the batteries as a set to be safe. If you can find a high capacity set of 4 (more being ideal) (with 850mAh minimum/900+ preferred), ditch the Alkalines for good. You can get away with carrying 2 sets in most cases, but if possible see if you can bring a battery charger (anything will work, but this is what I use) with you so you can always have a charged set that gets circulated. If mine is too expensive, this model looks like a descent option - but it doesn’t handle NiCd or LiOn cells.

In the future, it’s also a good idea to note when the batteries and backup battery were replaced so you have a aging point, especially for the coin cell as these last ~5-10 years, unlike a set of alkaline batteries that die in ~6-8 months.

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Oh come on! I have one job here and you beat me to it! :P

Fantastic answer!

Don't sleep at the wheel next time :P.

@nick I don’t think it’s the coin battery as I checked its voltage and it was pretty close to the voltage of the battery, don’t remember how much exactly so I assumed it was good but I can try to replace it.

The reason I think it’s not because of the battery is because sometimes the calculator just turns off if I touch on it or move it, it’s weird, but I’ll try to replace the battery. Thanks

The coin cell can look okay but may not have much charge left. The LR44 TI uses from the factory (NL in mine) is a 144mAh cell. Others may hold more but the OEM LR44 isn't long lasting.

They're only a few bucks so if doesn't hurt to try if you already lost the RAM backed content.

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Hi, check this figure. For the randomly turning off issue, you may fix it by soldering the anode of the battery to the PCB board anode points (any of these blue circle positions are the same anode if you check it with your multimeter).

The electric contact of TI-84 Plus is problematic. Whenever the contact surface area is insufficient or the current demand is large, the calculator circuit will draw electron from the anode material (which is the copper in TI-84 Plus) and rust the anode until the material is consumed and break the contact totally.

Hope this will help you.

Block Image

The anode position may different depends on the version. It’s better to check the resistance of the contact points to be 0!

Now it’s working perfectly.

Block Image

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BTW, if your RAM is clearing randomly, you may want to solder the ground (that spring) of the button cell to the anode contact as the picture shown.

@miaorn That's an interesting solution, how often have you been able to fix this problem by soldering the connectors together?

@thelastmill I've only got one piece of TI-84 plus and fixed it by this method.

@miaorn Mine is fine, but I also did the NiMh swap early on and never looked back. Would that protect a good one?

@nick do you mean the main-power NiMh swap or the swap applied to the button cell power, too? I think they're two different cases with the same poor contact issue. The RAM is sustained by the button cell, whereas the turning off is due to the main-power contactless.

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