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TI-59 Reconditioning Guide

Preamble

This Guide was prepared by fellow calculator collector Marek Czeszek and is published on his website. Marek granted  the Datamath Calculator Museum in April 2008 the rights to use both his pictures and text.

The information in this Guide was compiled carefully but we are not responsible if someone destroys his calculator!

Introduction

Most common troubles with TI59 calculators are caused probably by their magnetic card readers; this article should help you solve these problems. Below, I've only included repairs that do not require breaking into electronics (without soldering, to be precise). The card readers of the TI59s are, to be sure, very solid and reliable, but with time they wear away or simply get dirty.

Since the other elements (electronics, keyboard) could go out of order as well, therefore not any card reading problem stands for the card reader damage.

Thus, before you disassemble the calculator (its always a little bit risky!) I suggest to try the following:

1. Control the voltage of Battery Pack BP1 or BP1A (it should be ca. 3.6V),

2. Try to work with AC adaptor/charger (AC9131, AC9900/H, AC9900/Ht) AND battery pack together,

3. Use Cleaning Cards,

4. Put some alcohol or magnetic head cleaning liquid on the Cleaning Card. They are saturated with cleaning solution, but with time they could be just dried.

5. Try to use other (surely good written) magnetic card.

If the above doesnt help your card reader is probably really damaged (or, at least, dirty) and you have to repair, or clean it. Its a good opportunity to clean the whole machine thoroughly.

If you are afraid, that your experience in electronics and mechanics is not sufficient I suggest to charge whichever "wizard" for this task. Keep always in mind, that: 

THERE ARE NO SPARE PARTS FOR THESE OLD CALCULATORS!!

It means if something goes wrong you can get the spare parts only from another machine. Repairing the damaged parts is mostly either very hard, or impossible at all.

This article was written only for informational purpose. The author takes no responsibility for any consequences of using this information, especially if someone damages his calculator or himself.

You can download, copy, share with friends and print out this article but:
You cant use this materials for any commercial purpose, or for any public display (commercial or noncommercial),
Modify the materials,
Remove any copyright, or other proprietary notations from this materials.

Thanks to Michał Wronko for helping to prepare of this article.

What do you need?

1. Flat screwdriver, or small coin,
2. Precision Philips screwdriver,
3. Precision flat screwdriver (max. 2 mm wide),
4. Sharp knife,
5. Precision pliers,
6. Several cotton swabs for cleaning,
7. Soft rags or paper for cleaning,
8. A small brush for cleaning,
9. A piece of plastic foil,
10. A 68 x 95 mm piece of ca. 2 mm thick sponge (optionally for exchange).
11. Alcohol and/or magnetic head cleaning fluid,
12. White spirit (only for gear cleaning!),
13. Paraffin jelly or similar light lubricant,
14. Common dental cream for polishing of display filter,
15. Common dish detergent,
16. A small box for the small parts.
17. Enough of time, patience, skills and maybe a big hammer (in case of last despair).

On all the photos below the points of interest are marked in blue; the things to move (press) are marked in orange.

Step-by-Step Instructions

1. Removing of the Battery Pack BP1 or BP1A.

First of all disconnect the AC adapter/charger. The electronics of your TI59 could be irreversibly damaged when working with AC adapter/charger without battery pack inside!

02-coin.jpg (80037 Byte)Then lever the battery pack with a small coin (or flat screwdriver) and take it out. If you suspect, that the battery compartment got dirty (NiCd rechargeable batteries are corroded, or even leaked) remove the Library Module first, then open the case and try to remove the battery pack. Be careful the cells and leaked chemicals are toxic! Follow your local rules of disposal. 

2. Removing of the Library Module.

03-module.jpg (50898 Byte)Pull the module cover out. The module itself should drop out free; its fixed only with the cover and contact springs. 

3. Opening of the Case.

04-main-screws.jpg (60579 Byte)Using Philips screwdriver turn these two screws out.

05-case.jpg (27235 Byte)Raise the case up and simultaneously shift aside, as the arrows show. There are two plastic catches inside dont break them.

4. Removing of the Main Board.

06-drive-screws.jpg (74271 Byte)Using Philips screwdriver turn out the four screws holding the main board and drive.

07-mainboard-catches.jpg (91545 Byte)Push the both plastic catches of main board as shown. Do it very gently they are really easy to damage (break). Note, that the catches dont hold the main board immediately, but the keyboard module underneath. 

08-mainboard-lever.jpg (83973 Byte)Lever the main board with drive (from both sides) with a flat screwdriver and pull them up.

5. Cleaning the Case, Keyboard and Display Filter.

09-mess.jpg (104887 Byte)Probably after removing the main board it will be somewhat messy (therefore its really not bad idea to notice the keyboard layout in time; anyway dont worry! www.datamath.org and www.rskey.org are always helpful for you).

10-display-window.jpg (48415 Byte) Remove the red display filter pressing both plastic catches with your thumbs as the arrows show. 

Now you can clean the case, keys and display filter with some common dish detergent. Additionally you could polish the filter with common dental crme. Dont polish the gold letters (if they survived up to now) they will rubbed out!

Try any cleaning liquid first on an invisible place some stronger detergents could be pretty aggressive!

6. Exchanging the Sponge.

11-sponge.jpg (92533 Byte)The sponge is not fixed (glued) to the keyboard module it should remove freely. Probably its very old and will tear into parts. Its not a problem clean gently the module form the rests of an old sponge and simply lay a new piece on it. Dont glue the sponge to keyboard module.

7. Unplugging the Ribbon Cables.

12-ribbon-band-connectors.jpg (71692 Byte)There are two ribbon cables to disconnect. Pull up the connector (best of all in very small steps, both sides alternately). Notice the correct layout of the bands (blue arrows).

8. Disassembling the Drive.

13-drive-spring.jpg (75734 Byte)After disconnecting the flexible cables you can take out and disassemble the drive. Lever the holding spring (as shown) it should jump out (probably you need a precision pliers or tweezers to set it back). There is NO other way to open the drive. If you try something other you will harm it probably irreversibly.

9. Cleaning of the Drive.

14-drive-cleaning.jpg (78336 Byte)There are four things to clean with alcohol or magnetic head cleaning fluid.

1. Pinch roll.
2. Magnetic head clamp,
3. Magnetic head front,
4. Capstan (probably you can clean it better after dismounting the gear).

10. Removing of the Gear.

15-tape-switch.jpg (48786 Byte)First lever the card sensor switch. It holds at the point marked with blue circle. You dont need to remove it entirely its enough to make some room to pull the capstan out. Its reasonable to try to lever this spring in several points.

16-band-glue.jpg (59421 Byte) Now detach the ribbon cable as shown (fortunately the glue doesnt hold too strong).

17-gear-main-screw.jpg (32767 Byte) Pull very carefully the ribbon cable up and turn out the main screw holding the gear.

18-motor-screws.jpg (107447 Byte) Turn out the two (and only!) screws holding the motor (marked with blue circles). Now you can take the gear out.

11. Cleaning of the Capstan.

19-capstan-cleaning.jpg (40335 Byte)Having the gear out of drive you can thoroughly clean the capstan with alcohol or magnetic head cleaning fluid. Its essential for correct transport of magnetic cards.

12. Disassembling the Gear.

20-gear.jpg (41047 Byte)Turn out the four screws and lever a gear cover. If it doesnt go with your fingers use the sharp knife (notice the blue arrow) to lever it.

13. Cleaning and Greasing of the Gear.

21-gear-cleaning.jpg (48066 Byte)Now you can clean the cogwheels. Do it, best of all, with white spirit and small brush. Its a good idea to prepare a small piece of plastic foil (cut as shown) and fix on the capstan shaft, to prevent the capstan from grease. 

22-gear-greasing.jpg (70208 Byte) You can put a small drop of lubricant on the capstans shaft and some paraffin jelly (or similar grease) on the cogwheels and their shafts. I would suggest to use a sour free medical Vaseline for this purpose. Theoretically its possible to take out the last two cogwheels, but its very risky, and in fact unnecessary. They can be as well cleaned and greased on their places.

14. Congratulations!.

If youll find mistakes, errors or lacks simply email me: marekczeszek@t-online.de Ill be grateful for any critical advices.

 

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If you have additions to the above article please email: joerg@datamath.org.

Marek Czeszek and Joerg Woerner, May 28, 2009. No reprints without written permission.