TI-89 Accelerate Troubleshooting

Soldering

Be careful not to burn up C10 (it is a very small SMD) or any other part of the calculator. Use a pencil soldering iron (15-30W) and don't touch the parts longer than 4 seconds.

Make sure you don't have a short circuit somewhere (soldering tin or small pieces of cut wires)

Implementing a variable capacitor or switch

It is important that you use proper tools, otherwise you may damage the back of the calculator. I suggest to first take off the back and cut out the whole, secure the var cap or switch with glue and then solder the wires.
Be sure you choose the right position of the var cap or switch (and the right size of it) so it doesn't damage the interior of the calculator.

Just removing the capacitor

This procedure is not recommended with the TI-89 it will cause your calculator to freeze.

Why is my TI-89 not as fast as I expected

If you have implemented a variable capacitor or switch, make sure that all your wires are as short as possible otherwise your calculator won't be as fast as it could be.
Use new batteries. Rechargeable batteries are good for the environment but bad for the speed since their voltage is only 1.2V not 1.5V
However there are some rechargeable batteries e.g: Rayovac Renewals which have a voltage of 1.5V, they are the best choice.

What can I do when my calculator turns on with a few rows of black lines, scrambled output or nothing

First check for short cuts and make sure the wires are isolated properly. Set the display contrast to maximum. Make sure you use new batteries. If this doesn't work, try this:

Remove all batteries (backup battery included), press "ON" about ten times and wait a few minutes. Put the batteries back in and try to start the calculator again.

If this doesn't work, try this: Take out all batteries (backup battery too) and make a short circuit: connect P1 and P4 with a wire and wait a few seconds, remove the wire, put the batteries back in and turn the calculator on again.

--------------------------------------------------
|
| 
|  ~~~~~~~~~~~~~~~~~~~~~
|  ~ P                 ~
|  ~ 1                 ~
|  ~ ----------------- ~
|  ~ P                 ~
|  ~ 2                 ~
|  ~ ----------------- ~
|  ~ P                 ~
|  ~ 3                 ~
|  ~ ----------------- ~
|  ~ P                 ~
|  ~ 4                 ~
|  ~~~~~~~~~~~~~~~~~~~~~
|  
--------------------------------------------------
 

If your calculator still doesn't work, try to restore the original configuration: remove the 22pF cap and put back the old C10
If this is working you may try to use 27pF instead of 22pF, this is more stable but makes the TI "only" about 1.5 times as fast as with the original capacitor.

I accelerated my TI-89 one year ago and I didn't have any troubles with it. I have a variable capacitor and was able to check out where the limit of the acceleration is by increasing the speed and checking whether the calculator was still working properly.
If you go too high you will see that some characters in the menus and on the command line will be scrambled (e.g. if you type "sin" you end up with "syn") If you have a variable capacitor just reduce the speed until this problem disapears and then reduce it again a little to be sure. That's what I did and it's working perfectly.

Note: Please don't e-mail me if something goes wrong, I'd like to help you, but I'm quite busy and I couldn't do anything else than telling you what I have already written on this page, sorry.

However...

As long as you take your time and carefully follow the steps listed on the page almost nothing can go wrong ;-)