AA-5.200

Adding a 5th AA cell to your model 200.

Recently, an idea to add a 5th NiCd to the Model 200 surfaced in the message
section of the SIG. The following article is the result of this concept.

Purpose:
  The purpose of adding a fifth cell to the T-200's battery pack is:
   1. Prolong total battery life in the T-200 so that it requires
      fewer charges.
   2. Return T-200 operating voltage to 6VDC.

Limitations:
   The only limitation is one of operation. Instead of charging the cells
continuously, the T-200 will charge (mainly) while the unit is off. Since
most applications involve the T-200 being ON during the day and off at night,
it is no problem to run the unit in the day, and charge it at night by parking
it next to a battery charger (RS# 26-3804).

Warning & Disclaimer:
   In-as-much as this is a very easy mod to perform, some competence is
required. If you aren't familiar with the T-200, or comfortable with poking
around inside, then, by all means, DO NOT PERFORM THIS PROCEDURE.
   Performing the mod will void your warantee. This mod can be easily removed
as easily as it was perfrmed, if necessary.
   I completed this mod with no problems, however, I cannot accept any
responsibility for any damage done to any equipment, nor damages resulting
from or arising from the performance of this mod. All I can say is:
   It works for me.

Materials:
  Battery, NiCd, with solder lugs (RS# 23-191 - pkg of two) - one req'd
  Wire, stranded, fine, 4" long
  Soldering iron
  Solder, fine, electronic
  Screwdriver, Phillips, medium

Preliminary:
   The first thing that must be done is to perform the RECHRG.200 mod to the
T-200. AA-5.200  is performed after RECHRG.200.
   It is recommended to first charge the new battery. The easiest way to do
this is to replace two of the NiCds with the new batteries. If you only get
one battery, replace only one. Plug the T-200 into AC Adapter and leave
overnight.
   BACK-UP ALL VALUABLE DATA/INFORMATION. I performed this mod with all data
undisturbed. The computer acted as if its batteries were being changed (ie. it
powered up in the main MENU).
   Put the computer into the main MENU. Turn Computer off.

Precaution:
   Since MOS devices are very sensitive to static, it is recommended normal
anti-static precautions be observed. If you don't have access to the fancy
anti-static equipment (most people don't), then touching ground on the computer
before touching anything else, and maintaining contact or periodically touching
ground will work. If possible, perform this procedure in an uncarpeted area
(kitchen table, garage, whatever).

Procedure:
    I. Remove four screws from the back of the unit.
   II. Flip top open to first detent. Gently open lid completely to the full
       open position. This exposes the connector access cover for removal.
  III. Rotate computer such that screen is near your body and the keyboard
       is furthest away.
   IV. Using your thumb, press on lower access cover between the [ 4 ] and the
       [ 5 ] below the screen. Press with firm and constant pressure. Be
       careful not to break it. As long as you're careful, there should be
       no problem.
    V. Remove access cover.
   VI. Unplug ribbon cable. Careful.
  VII. Close lid.
 VIII. Open computer
       A. Press in on the black case on the BCR side, then the front (center),
          then on the DISP adjustment. This releases the plastic hooks that
          holds the computer assembly to the display assembly.
       B. Lift off the display assembly.
       C. Fold back keyboard so it is out of the way.
   IX. Locate battery compartment
       A. Rotate computer so that battery compt is to your lower right.
       B. Locate battery connector (white w/ red & black wires).
    X. Disconnect batteries
       Unplug battery connector. Since we are soldering on sensitive components
       it is best to isolate the work we are performing.
   XI. Remove positive lead (RED)
       Using soldering iron, desolder connection.
  XII. Solder pos (RED) lead to pos on new battery.
 XIII. Solder 4" piece of wire to neg terminal on new battery.
  XIV. Solder other end of wire to pos lead on battery pack.
   XV. Plug in battery connector.
  XVI. Using black vinal tape (electrical tape), tape battery in place
       The best place is alongside the old battery pack, just outboard of the
       small plastic post by the buzzer. The new battery will fit nice and
       snug. Tape it into place.
 XVII. Re-assemble computer
       A. Return keyboard to normal position. Be sure cardboard insulator is
          in place.
       B. Feed ribbon cable through slot in display assembly.
       C. Snap together computer and display assy.
       D. Plug ribbon cable into connector. Ensure cable is seated firmly.
       E. With display in full back position, snap into place the lower
          access cover.
XVIII. Op check computer
       Turn it on. If your display does not show the MENU, ensure the ribbon
       cable is plugged in squarely and securely.

This completes the 5th cell modification. Total time to complete is less than
ten minutes (this includes soldering iron heat-up).

Final Note:
   From a totally charged condition, the on time was raised from 6hrs 15min
to 8hrs 15min - an improvement of 2hrs. And this time should increase with
use and cycling of the new battery. See PWRDAT.200 in DL4 for more info.


                      +---------------+  
                      |               |  
                      |  Robert Toft  |  
                      |  [74716,476]  |  
                      |               |  
                      +---------------+  
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