Nspire CX some keys do not work.

→ **MyCalcs** profile · by **jdcx** » 03 Aug 2023, 01:06

Ti Nspire CX keys do not work. Every time when Nspire CX starts up, it opens a Scratchpad with the display "wqke[<none>]". You guessed it right, the w q k e and enter keys do not work! I am pretty sure it is not the problem of the keypads. I switched the whole keypad module from a working one, but the problem still there. I tried to solder the LCD screen / keypad connections, but still no luck. Not sure what is the problem. Maybe memory issue?

→ **MyCalcs** profile · by **critor** » 03 Aug 2023, 10:18

Hello.

For information, what's your (faulty ?) TI-Nspire CX hardware revision ?

It's the short code shown on the back at the right of the serial number :
1 letter + 4 numbers + 1-2 letter(s)
Example :

→ **MyCalcs** profile · by **jdcx** » 03 Aug 2023, 14:12

P-0611C

→ **MyCalcs** profile · by **critor** » 03 Aug 2023, 16:40

Thanks.

Is the replacement keypad PCB coming from the same TI-Nspire CX model ?

Because you can't switch keypad PCBs between different TI-Nspire CX models.
A TI-Nspire CX CAS keypad PCB won't work in a TI-Nspire CX.
And a TI-Nspire CX keypad PCB won't work in a TI-Nspire CX CAS.

A CAS/NONCAS mention should be readable in the reference printed on the keypad PCB .

→ **MyCalcs** profile · by **jdcx** » 03 Aug 2023, 17:09

Yes, I have another fully working Nspire CX which is P-0711C, I switched the LCD with PCB board head unit, now the P-0711C keys not working and P-0611C works. It seems not the problem of the keypad.

→ **MyCalcs** profile · by **jdcx** » 06 Aug 2023, 23:54

Checked around, looks like quite a few had the exact same issue. No solution found yet. The other calculator worked fine now can't start anymore.

MyCalcs profile · by **CVSoft** » 07 Aug 2023, 02:29

I have at my house a P-0611C Nspire CX EZ-Spot with an identical failure. Per Reddit, reflowing the CPU ASIC can fix it, but I haven't been successful with this. I think it's some failure within the ASIC itself. Putting a good amount of padding between the ASIC and the housing in order to apply about a pound or three of pressure to the chip when the calculator is reassembled can mitigate the issue.

→ **MyCalcs** profile · by **jdcx** » 07 Aug 2023, 02:42

Thanks for the information. I guess the CPU is a BGA package? Not sure if a heat gun can do the trick. I will give it a try.

→ **MyCalcs** profile · by **critor** » 07 Aug 2023, 08:08

CVSoft wrote:I have at my house a P-0611C Nspire CX EZ-Spot with an identical failure. Per Reddit, reflowing the CPU ASIC can fix it, but I haven't been successful with this. I think it's some failure within the ASIC itself. Putting a good amount of padding between the ASIC and the housing in order to apply about a pound or three of pressure to the chip when the calculator is reassembled can mitigate the issue.

It reminds me I have a TI-84 Plus with a similar issue.

Suddenly, the whole bottom-row of keys stopped working, implying an electric or electronic failure somewhere.
I tested the circuit conductivity successfully from the faulty row up to the matching ASIC pin, meaning something suddenly went bad inside the ASIC...

→ **MyCalcs** profile · by **jdcx** » 07 Aug 2023, 16:09

New updates. I put the main circuit board in the small oven, set the temperature to 240C (max temperature) and baked it for 5 minutes. Magically, it worked. I wouldn't suggest anyone doing this unless you have no other solutions. The foam on top of the CPU was totally burned. I tried to peel it off before bake the board, but can't make it clean. Not sure what is the purpose of this foam, it works just fine without it.