Due to space constraints, I had to sell my Polysix. I'm leaving these pages here for reference, but it is unlikely that there will be any updates in this section

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As mentioned on the previous page, Polysixes incorporate a Nickel Cadmium (NiCad) battery to power the memory circuits.  As they age the NiCads fail and leak battery acid on one of the circuit boards.  If you still have a NiCad battery in your Polysix, I highly recommend that you replace it immediately.     Obviously, it's possible to replace the battery with a new NiCad, but I prefer using a Lithium battery to avoid a corrosive leak ten or fifteen years from now.

To change the battery, open the Polysix's top panel.   Remove all connectors from the KLM-367 circuit board.  These connectors are glued together to prevent them from coming loose, so you'll need to cut or crack the glue before removing them.  Be extremely careful to avoid breaking the solder joints beneath the connectors.  Also note there is one right-angle connector on the rear edge of the board - it's easiest to remove this connector last, after loosing the PCB from it's mounting screws.  Finally, my Polysix had a heavy gauge black ground wire soldered to the KLM-367 board.  After desoldering this wire, the board is ready to be removed.

With the KLM-367 board on the work bench, it's now simple to remove the old NiCad.  Cut the solder tabs off the battery and remove it.   Using a soldering iron with solder wick or a desoldering bulb, carefully remove the remaining pieces of the battery tabs and clean the mounting holes. 

Next, I bought a 20mm lithium coin-cell (CR2032) and a matching PCB mount holder from Radioshack, and installed them in the board.  Please observe polarity... the negative end of the battery is easy to locate because it ties to the heavy ground trace that runs along the outer edge of the KLM-367 circuit board.   The positive side connects to (2) pads on the circuit board.  Unfortunately the 2 positive leads of the coin cell holder don't line up with the pair of holes on the circuit board.  I simply cut one of the two leads off, and mounted the holder to a single hole instead.  A dab of hot glue beneath the holder will assure it doesn't ever break loose.

Now you need to disable the charging circuit.  To do this, remove R91 and C40.  Both are mounted right next to the battery holder.   Now you need to add a diode in the hole R91... I used a 1N914 and placed it in the holes formerly occupied by R91.   The diode should face the opposite direction of D15 directly beside it.  This diode allows current to flow out of the battery, but prevents the charging circuit from pushing current back into the battery.

Shown below is a rather fuzzy picture of the complete installation.  This was taken after the board was reinstalled in the Polysix.   Directly below the battery is the circle  that C40 used to occupy.    Directly to the right of C40 is the new diode that was installed in R91's position.   I used photoshop to help show the orientation of D15 and the new diode... observe the bands on the diodes to make sure they are installed properly.

Double check your work, and reinstall the KLM-367 board into your Polysix, and replace all of the connectors.  Now you can place your battery in the holder.  Don't forget to resolder the ground wire if your Polysix has one (I think this was a revision, and only later Polysixes will have it).  When you're finished, close up the lid and test it. 

If you find that there is damage to your board from the leaking acid, be sure to check Old Crow's Polysix Pages.   He has a very detailed description of everything I've mentioned here in addition to the procedure to repair corroded traces.  He includes several pages of step-by-step instructions, including the proper way to open the case, etc.