Overclock – Hardware revision (F)

    I noticed how difficult it was to find overclocking info about the TI 83+. Indeed, all links we can currently find lead to O/C of the TI 83, which is quite different from the TI 83+. I finally got to the right page, so I put back this simple process.

As usual, I won't be responsible if you screw up your calculator using these technique.

    A professional overclock: the noverclock

 

First step: the tools

    Make sure you have the right tools:

- Soldering iron, 30W max, with thin tip, ideally in U for SMC
- Desoldering pump (optional)
- Electronic solder 40%Pb, 60%Sn (not less), possibly with silver, about 2%
- Torx #6 screwdriver For those who cannot find ones, I sell some for $10CDN ($7US). However, more than one version of the back cover screws may exist, so be sure yours are of this type.
- Flat screwdriver, with preferably rounded corners
- AAA/R3 format rechargeable batteries (optional, unless you don't want to buy new batteries every two weeks)
- A cable compatible with your computer, and the correct software. In fact, when you will remove the back cover of the TI, you will be forced to remove also the RAM auxiliary battery. So you have two choices: either you archive in ROM all data you want to keep; or, if you don't have enough room in archive memory or want increased security, you'll have to copy data to the computer.

Once all the tools have been gathered, you can go on

 

Second step: data backup

Do one of the following operations, or both if you can:
- Turn on the calculator then copy all RAM data to Archive
- Connect the calculator to the computer using cable of your choice, then use corresponding software to send all the memory of the calculator to a folder on your hard drive.

 

Third step: opening the calculator

    Get assured that your calculator is off, then remove all the batteries, including RAM lithium auxiliary. If you don't remove the last one, opening won't be possible

How to remove the batteries..and the screws

    Take the Torx screwdriver, then unscrew the screws that keep back cover in place (There are 6), and put them in a sure place to not lose them.

    As you can see on the picture below, there is a little clip on the calc's side that holds the two halves of the case together. With the flat screwdriver, exert a light pressure on place shown, repeating a few millimetres further along the case. Best technique is to slide the screwdriver along the groove while pressing slightly at the clip's level's. We understand here the usefulness of a rounded corners screwdriver not to fuck off your case.

    We can also use the battery cover.

Useful proportions

Picture 1: Where's the clip located on a TI 83+SE. Same place as the TI 83+.

    If the work is well done, calculator should open on the side you started. To unlock the other side, exert a slight lateral movement on the bottom part of the case, holding it by the grooves while holding keys side. Other side should get out without problem. Now, pull slightly bottom part of case toward yourself (I/O port facing you) to separate it from the upper part (keys).

    Voilà ! Here it is, you should have a beautiful green epoxy circuit under the eyes !

    Remove the little screws that hold the shield in place then admire ! Click on the second picture for a close-up. Beware ! This pic is heavy !

Aluminum shieldingGeneral view on the inside of a TI 83+

 

Fourth step; spot the interesting zone

    It is located below controller (according to NSPIRIT). It is the C11 capacitor.

Zoom on the capacitor to change    You have to desolder this component as indicated by the graphic below;

How to desolder the capacitor
Thanks to "The Rich Files" for this animated gif.

    The best way to proceed is to use copper braid to absorb all "old" solder.

 

 

 

 

 

 

 

 

 

 

 

 

Fifth step: replacing and testing

    Once you have desoldered the old capacitor you only have to replace it by another in which the C value will be calculated as below, knowing that the original capacitor is 27pF.

Capacity C (162/f) in pF

Theorical frequency obtained (6 x (27/C)) f in MHz

27

6 (Run frequency set by TI with power consumption in mind)

20,25

8 (Processor factory set frequency)

16,2

10

14,73

11

13,5

12

11,6

14

10,8

15

9

18

8,1

20

6

27 (The highest stable frequency ever achieved (not by me))

    Take one of the above values, or calculate one yourself using the formula. Use preferabily a surface mount capacitor, but a classic one will do the job. But be careful to shorten the leads, otherwise a capacity may appear between them, affecting the total capacity perceived by the calculator and thus slowing it down. Also take caution when soldering on the thin tracks, they can come off.

    Once you have placed the new capacitor, put fresh batteries and turn on the calc. If no particular sign is visible, continue. If on the other hand lines appear on the screen, try to replace the capacitor by one with a higher value to lower the CPU's frequency.

    Finally, I say it again, this change in your machine, in addition of voiding the warranty, consumes much more power than on ordinary speed, that's why TI slowed down their TI 83+.

 

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