Did something rather hilarious earlier today. I haven't even turned on my TI-30 in about a year, so I threw a battery in it to see what kind of shape it was in. MOST of the keys didn't respond, at all. You could pound them forever and not get a single response. So I decided to, for the first time, open it up and see just what kind of shape the keypad is in, and if I can do anything about it.
Aside from a sheet of thin foam between the buttons and the keypad itself that had disintegrated, everything looked normal. Oddly enough, the keypad appears to be the exact same design as used in the TI-1025, yet my TI-1025's keypad works (worked
) as perfect as could be. As far as I know the TI-1025 doesn't suffer keypad issues, so I really don't know. Both calculators were on the market simultaneously, so I can't imagine the internal keypad design being different between them.
Anyway, there are some holes on the underside of the keypad, so I tried blowing compressed air through them. Nothing. So, I decided I had nothing more to lose, so I tore the whole keypad apart, basically destroying it. The first picture is of the calculator before I tore the keypad to bits. You can see where I started to do so at the bottom-left of the keypad.
The keypad design is pretty simple. There's multiple stiff wires running vertically down the keypad base. Laid on top of them are the buttons themselves, which are just metal circular discs which snap downward when you press them. The metal discs are arranged in strips, so there's 8 strips of 5 discs each for the 8 rows of buttons on the calculator. Each strip is soldered to one of the vertical wires, and when you press a button, the disc contacts another wire, thus shorting the two wires. The discs are held in place by the black plastic sheet, which is glued to the base of the keypad.
I tore the plastic sheet off. All the strips of metal discs came off with it, tearing from their solder points. You can see the entire parted keypad in the second picture. I don't know why so many buttons weren't responding, but I found the problem for at least some of them - some of the vertical wires actually had green corrosion on them. This thing apparently suffered a leaking battery at some point in its life. Odd because it shows no other signs of ever having been so. Some of the metal discs had green corrosion, as well. I sanded everything clean.
Obviously I tore the metal disc strips from their solder points, and the black plastic sheet holding them wasn't going to stick on like it originally did. So, I stuck everything back together with tape. And there are small holes on the underside of the keypad base where the disc strips solder to the vertical wires, so I did the crappiest solder job in history, soldering the strips back on the wires by basically melting solder onto my iron and shoving it in the holes. In the end, I did get everything soldered and put back together. But my God, you wouldn't believe what it looks like. The top side of the keypad is a torn-up plastic sheet covered in tape, and the underside is melted plastic with blobs of solder everywhere. It looks horrible.
The hilarious part? Not only does the keypad work after that, but it actually works better than it ever did. The only key that doesn't work absolutely perfect is the 9 key, which you have to press harder than normal. I couldn't believe it. I forgot to take a picture of the keypad before I re-assembled the calculator, but I'll do that sometime.
