Hi, does anyone know what might be wrong with my TI-84+? A whole row of keys is unresponsive although everything else seems to work fine. I cannot use the LN and minus (sign) function, or input the numbers 4, 5, and 6 because the calculator won't register it.

I don't know if I need to replace the motherboard or something. (And if I do, could you recommend how I purchase one?)

Thanks in advanced for the help.
It does indeed sound as if the mainboard got damaged. Did you have batteries leak in the battery compartment at some point, by any chance? Unfortunately, replacing the mainboard is tantamount to replacing the entire calculator, so unless you have experience with soldering, your best bet is to find a relatively cheap used calculator on eBay/Craigslist/your friendly neighborhood thrift shop.
Best case scenerio, there's gunk between keyboard layers. You could take it apart and try cleaning the metal/rubber contacts. And eh, if you have PayPal, I'm selling a TI-84+SE for reasonable. :S
Eek...I did have batteries leak in the battery compartment. I already cleaned the keyboard layers, so the problem probably isn't gunk, unfortunately.

Is it really difficult to replace the mainboard?
No, just expensive (in fact just an hour ago I switched a couple of 84+SE motherboards). A mainboard, to my knowledge, is only marginally cheaper than a whole calc, unfortunately.
Remove 6 screws in the back with a jeweler's flathead screwdriver, then the screw holding in the backup battery, use the same screwdriver to pry the two halves apart, remove 6 more screws that hold down the mobo, and reverse progress for new one. Course the screen is stuck permanently to the mobo too for added cost.
Yeah, I didn't remember it being difficult to take the calculator apart. I guess there's no saving this one then. This is unfortunate...
pikarawrz wrote:
Yeah, I didn't remember it being difficult to take the calculator apart. I guess there's no saving this one then. This is unfortunate...
If you're comfortable with a multimeter and a soldering iron, you may be able to find where the discontinuity in that row of the keyboard matrix and bridge it with a thin conductor, but if you're inexperienced with EE types of things, it might be a steep learning curve. Sorry to be the bearer of bad news. Also, part of the expense of the mainboard replacement is that the LCD generally cannot be detached from the mainboard easily on the TI-84 Plus line, so you're essentially replacing everything except the plastic case.
Just beware of throwing them away, since even broken ones get about $30 on eBay.
  
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