Login [Register]
Don't have an account? Register now to chat, post, use our tools, and much more.
A friend of an acquaintance of mine gave me her TI-84 Plus Silver Edition to repair. The problem is that the calculator is unresponsive.

When I turn on the calculator, the cursor appears on the screen, but does not blink at all. When I press any key, the cursor starts blinking, but nothing else happens: no menus, nothing, just the home screen. There are two exceptions to "any key": the ON key and the right arrow key. When I press these, nothing happens.

What have I tried? I have taken out one battery, multiple batteries, and all batteries, including the lithium battery. None of these has worked, although when I took out one normal battery and one lithium battery, and let it sit for a few minutes, it at least showed the "RAM Cleared" screen before returning to unresponsiveness.
I have tried reinstalling the operating system by computer. It acted as a working calculator would in receiving the OS, with the "Receiving..." screen. However, once it received the OS, it returned to unresponsiveness.

What should I do next? What is the most likely cause of this problem?
Has something been spilled on this calculator?
It does indeed sound like a keyboard issue, either because of a substance spilled on the keyboard, a stuck key, battery corrosion causing degradation of the keyboard matrix traces, or some combination of these factors. Opening the calculator up and looking for these problems might be a good idea, if you're comfortable with that.
I needed a type of screwdriver, which I don't have, to open the calculator, so I opened it at robotics.

I found no signs of corrosion, a stuck key, or spilling in any of the hardware.

Actually, all I succeeded in doing was losing a screw (luckily not important), scratching the LCD, and disabling part of it: a strip of the LCD is completely blank.

What else could be the problem with the calculator?
IMPORTANT DEVELOPMENT:

I recently wrote a simple program that controls another calculator by sending keypresses through the I/O port. I connected a working calculator to the broken TI-84+SE. I could perfectly control the calculator!

This proves that what KermMartian and tifreak8x said is right: it is simply a problem with the keyboard. The OS and everything else (except a strip of the LCD) is intact.

How do I fix this keyboard problem? Do I have to order a new keyboard? Is that even possible?
Yep, we tend to know what we're talking about. Wink No, the keyboard contacts are the reverse side of the mainboard, so you can't replace the keyboard without replacing the whole mainboard, at which point you might as well just buy a new calculator. If you are comfortable with a multimeter, you can try to trace each keyboard contact back to the ASIC to look for open circuits.
Today I specified the problem further. The problem key is the right arrow key. It seems that the right arrow key is stuck, so the calculator ignores any other keypresses, save for blinking the cursor.

I figured this out because, again, of the keypress program. I wanted to see if it were possible to safely reset another calculator through the program, so I went to the reset menu, and found that it constantly alternated between the RAM, ARCHIVE, and ALL menus.

I am publishing the program on ticalc.org, in case it might be useful to others.

I have a few questions: rather than using the hardware method, can I use a program that ignores the right arrow keypress? Or would this interfere with other calculator functions? How would I write this program?

The right arrow key isn't a major key for normal calculator use (no programs, etc.). To move between menus, the user could just use the left arrow key.
scAFwATLxpKzRCmVaHv wrote:
I am publishing the program on ticalc.org, in case it might be useful to others.
Don't forget to upload it to the excellent Cemetech file archives as well.

scAFwATLxpKzRCmVaHv wrote:
I have a few questions: rather than using the hardware method, can I use a program that ignores the right arrow keypress? Or would this interfere with other calculator functions? How would I write this program?
The short answer is that you can't, easily. The long answer is that you could write a keyhook to check the current key, and if it's a right arrow, ignore it. However, I suspect that the OS might not let you press any other key in the right arrow key's key group as well.
scAFwATLxpKzRCmVaHv wrote:
I am publishing the program on ticalc.org, in case it might be useful to others.


Could you provide a link?
The program hasn't gotten approved yet. I shall provide a link once it has, and publish it on the Cemetech archives.

EDIT: It seems that ticalc.org will not approve the program. I shall recreate the zip file and post it on Cemetech today or tomorrow.

EDIT: I have posted the file and am waiting for approval.
What is the program written in? Axe or Asm?
The program is written in Assembly.
EDIT: here is the link on Cemetech:
http://www.cemetech.net/programs/index.php?mode=folder&path=/84pcse/asm/programs/
Here is the link on ticalc.org:
http://www.ticalc.org/pub/84pluscse/asm/programs/
The program is titled "Control" on both sites.
  
Register to Join the Conversation
Have your own thoughts to add to this or any other topic? Want to ask a question, offer a suggestion, share your own programs and projects, upload a file to the file archives, get help with calculator and computer programming, or simply chat with like-minded coders and tech and calculator enthusiasts via the site-wide AJAX SAX widget? Registration for a free Cemetech account only takes a minute.

» Go to Registration page
Page 1 of 1
» All times are GMT - 5 Hours
 
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum

 

Advertisement