How to Turbo your TI-86
Calculator
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THINGS YOU NEED
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TI-86 calculator (Duh! =)
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Small Philip's Head screwdriver.
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A Soldering Iron- I recommend the Weller brand because they're cheap on do the job fine. Do not buy the large one. Buy the small soldering iron that is made to work with circuit boards! You can purchase one at any Home Depot for about 15 dollars. Look in the tools section.
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A soft rag.
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Soldering Wire
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HOW TO TURBO THE CALCULATOR
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Take out all the batteries out, even the backup battery.
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Unscrew the bottom two screws and proceed to undo the case. The best way to do this is to run your screwdriver along the side until it pops open.
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Now, open the case and this should reveal the protective foil underneath. Unscrew to bottom two screws to take off the foil.
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Unscrew the two screws holding the display board in place near the top. Lift it up, stretch it out and carefully put the soft rag underneath it. This is to prevent it from being scratched while you work.
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Once that is done, you'll need to locate the C-13 capacitor located near the bottom off where the display board used to be. It should be brown in color and vertical in length.
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Plug in your soldering iron and wait till it heats up. Once it is hot enough, you can begin to de-solder your capacitor. Apply the tip of the soldering iron to where the capacitor is connected to the board. Keep switching from top to bottom to correctly do this, otherwise you may burn it out and ruin it. At the same time, use your screwdriver to slowly pry it up as the solder get hot and lose. Eventually, it should come up.
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Remove the capacitor from the board and set it aside. Some calculators may be able to run in Turbo mode without the capacitor at all, it depends on the ROM version you have. Mine ran perfectly without any capacitor, I the ROM version 1.4. To check your own ROM version, push 2nd, Mode, Alpha, S. This should bring you up to a screen with the text "Enter Self Test?" and a number below it. That is your ROM version. Warning, do not push enter or this will erase you memory! Push exit to leave.
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If you have a different ROM version, you should test to see if it will work. Put the calculator back together and do a couple of graphs and some math. If it works with no problems then you have successfully turboed your 86! However, go on to the next steps if it doesn't work...
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*Note* If you have turboed a calculator with a different ROM version that ran fine without any capacitor, please E-mail me telling me the ROM version you have. This is so we can make a list of all ROM versions that work.
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Go on to the next section if you want to learn how to build in a switch to turn the turbo off and on.
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Since your calculator didn't work properly due to the ROM version, you'll need to install a 1 pF to add some capacitance. To do this, you'll need to purchase one from a distributor. You can buy a pack of these at any local Radio Shack for about four dollars. The ones I used were Low-pF Ceramic Capacitors and weren't anything like the original, but worked out fine. I also will sell you some for your convenience. Just E-mail me and I'll see what I can do for you.
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Once you have the 1 pF capacitor, place the ends were the old 22 pF capacitor used to be. Start heating up the solder on the circuit board and solder each end in place. You may need to use a bit more solder to hold it in place. If you don't already have soldering wire, get some. Hold the end of the wire right over where the one end of the capacitor goes. Next, heat the wire until it melts and quickly place it on the circuit board where the capacitor is. Do the same for the other side. Once you have the new capacitor in place, your calculator should now be turboed.
Installing a Switch
Introduction: There are times when your turboed calculator is handy and there are times when it is not. For example, I find it extremely hard to play any game when it is running many times it's normal speed, but I find it useful when it solves math problems in a snap! This is where is switch is needed, because not only will this feature allow flexibility, it will also save battery power as turbo mode takes up a lot juice, even when it's off. Adding a switch is the best way to go.
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Things you need:
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Your calculator
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A switch -This can be obtained from a local Radio Shack or you can scavenge an AM/FM switch from an old alarm clock. This is what I did and it worked fine, but if you choose to do this be careful not to break it! It will be in there pretty securely.
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Soldering iron.
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Solder
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Two 4" Wires
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A 22 pF capacitor -If you saved the one you took out, you can use it for this. However, if it was damaged you'll have to buy a new one...I broke mine :)
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A 1pF capacitor- This is optional depending on what ROM version you have. Mine didn't require one so I didn't put it in. Read up in the last section to see if your calculator meets the requirements. Besides, leaving it out makes it go even faster since the wiring add some capacitance, slowing it down some. Actualy, this will make it run a bit slower in normal mode so you may want to use a 20 pF instead of a 22 or lower.
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Installing the Switch:
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Once you have the items you are ready to begin. Start with the 22 pF capacitor, solder one end of this to the circuit board.
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Next, solder a wire to the other end of it.
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Solder the other end of this wire to the switch to the end prong.
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Take the other wire and solder it to the other spot on the circuit board.
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Take the end of this and solder it to the middle prong on the switch.
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Now, for the 1pF capacitor. (If you don't need it, go to the next step) Solder each end of this to the wires on the switch. Basically, put it between the prong on the switch where the wire is attached.
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Cut the silver shield enough to allow the switch and wiring to pass through easily.
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Everything is done! All is left is to make a nice niche for the switch to stay. The best place I think is to put it next to the backup battery and cut a hole through the battery paneling for easy access. I used the soldering iron to burn a whole through the casing and made the hole from the top of the battery case to where to battery is. This spot allows easy access and doesn't make your calculator look ugly or deformed. Hardly anyone will notice. You could put the switch on the side if you wanted to, but I wouldn't recommend it. It's your choice.
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Tidy up the whole and smooth it out with a file.
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Now put it back together and try it out!
Contacting the Author
I am always on my computer and the net. If you have any questions about or suggestions for this article feel free to E-mail me. You can also talk to me on ICQ. My ICQ number is 20751390. I also have AIM and my screen name is GastricGas.
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