Having got a bunch of graphing calculators laying around from eBay, it's my duty to overclock every single model to the max/until it's dead. This time, I'm showing you how to overclock your TI-85/TI-86. This model is different than the other ones, I think I got this one to about 3 times its stock speed. Three times! That's pretty good considering it's only a puny 6Mhz at stock. Let's get started!
1. Start by ripping apart the calculator. Do this by removing the two screws at the bottom, and don't forget the screw on the battery backup. Pry the calc apart, I found in my calc adventures that putting the battery cover into the bottom and slowly moving upwords to the top, works the best. Remove the silver foil.
2. There's the TI-86 motherboard. Pretty different from the TI-83, eh? Anyways, locate the CPU, the biggest chip on the motherboard and just right to the backup battery spot. Search around near the upper left corner of the CPU and find a capacitor labled 'C13' (OR 'C9 if your using a TI-85). This regulates the CPU at (I think) about 6Mhz. Remove this by desoldering one end, and then twisting it off.
Pic of the location of C13 on a TI-86
3. Once it's gone, we'll have to replace it with a lower rated one. Or do we?! I originally thought by instinct (Thanks to other TI overclocks) that just removing the capacitor would mess up the calaculator. I was wrong. After trying the good old 17pf capacitor and still ran stable, I kept lowering the pf, and eventually found that it was stable at as little as 1pf to no capacitor at all. It's your choice if you want to buy the 1pf capacitor, or if you want to go it cheap and not have one at all. I sometimes got some garbled lines and had to reset with no capacitor, you might want to use the 1pf capacitor just to be on the safe side.
IMO the best way to put a capacitor on is to put two small drops of solder on the ends, and then when the capacitor is in place, melt the solder and wait for it to cool to successfully mount the capacitor. If you're going capacitorless, connect the two points with a small amount of solder.
5. This is alot of delicate work, but when your done, run some programs, you'll see the difference! Note: If you get and messed up text, lines, or whatnot and you're running capacitorless, you'll have to use the 1pf capacitor. Also make sure there isn't any solder where it shouldn't be, you might be shorting out the board.
6. Have fun with the increased speeds, faster games, and gloating rights of your new overclocked TI-85/TI-86! I'd love some comments, I don't know what model to do next....
EDIT: Great eBay store for capacitors
here.
How to: Overclock my TI-86 graphing calculator?
08-26-05
How to: Overclock my TI-86 graphing calculator?
