To be able to make use of the bear, you will need to disassemble it and remove the circuitry so that it can be connected to the Raspberry Pi. Some of the tools you will need include a couple of sizes of phillips-head and Flathead screwdrivers, some isopropyl alcohol, and flush cutters or a soldering iron.
Disassembly
As you disassemble the bear, be sure to carefully set aside the screws and electronics as some of this will be re-used in the final circuit.
Turn the bear over and open the flap covering the battery compartment. You may want to remove the battery cover and batteries so you can use them for something else. They won't be used in this project.
The fabric around the electronics housing should now be free to pull away. Go ahead and pull the housing out of the bear.
To expose the housing, first carefully push the cloth around the housing up so that the bottom half inch of the housing is exposed. Then push it up the rest of the way.
The housing is attached further up with a bunch of hot glue. Applying some isopropyl alcohol (or IPA) to the glue with a cotton swab or something similar will cause the glue to become brittle and less adhesive. The higher the concentration of IPA, the better it works. Don't forget to remove the glue on the lower white wires.
Once the two halves of the housing are taken apart, you will have access to the electronics and wiring.
On the circuit board are connections to the power, mouth motor, arms motor, foot button, and speaker. Remove everything except the power wires because they won't be needed. If you are doing the easier build option or upgrading the speaker, you won't need the built-in speaker either. You can either use flush cutters or remove the glue and desolder each wire.
Preparing the Motor Wires
In order to connect the motor wires to the Adafruit Motor HAT, we recommend extending the thin wires with thicker jumper wires and a nice connector on the end.
If you don't mind the wires being short on the short side, you may want to try wire ferrules. These have the advantage of not being as deep and you don't risk melting the polyfill stuffing inside the bear. However, the wire gauge is a bit small and it's tricky to get the ferrules to stay on properly.
You could also combine the two methods and extend the wires with thicker ones and replace the long black connectors with the shorter ferrules.
With the 6" wires, by cutting in half, you can have 2 useable parts. If you would like longer wires, you can just cut off 1 end.
You'll want to cut, strip, and tin 4 wires to match the motor wires. You will also want to cut 4 pieces of heat shrink tubing. Place the heat shrink on the wires now so you don't forget later.
Strip and tin the wires inside the bear. Very carefully solder the wire extensions to the motor wires sticking out. You may want to temporarily remove some of the stuffing to give you more room to work and place some aluminum foil around the area you are working.
Now slide the heat shrink tubing up and heat it. I used a hot air soldering station set at 120° Celsius, which seemed to be just hot enough to shrink it. You could also use electrical tape to insulate if you aren't comfortable with heat shrink.
Preparing the Foot Button
If you would like to make it so the foot button can be disconnected, you can attach the JST SM Plug cable to it and the receptacle to the Pi.
If you are not using this connector, just strip and tin the pair of white wires coming out of the bear with a small knot in the end without shortening the wires.
Place some heat shrink tubing on the foot button wires. Since the wires are already separated, it make things a lot easier.
Strip, tin, and solder the harness to the foot button wires. The specific wire doesn't matter since pushing the button connects them together.
Slide the heat shrink tubing over the soldered wires and heat it up. Since the wiring isn't as short as the motor wires, this is much easier.
Preparing the Speaker
If you are reusing the speaker and you would like to use the terminal connector on the MAX98357, you will want to replace the wires on the speaker with ones similar to the motor. Otherwise, you can just strip and tin the existing wires.
That's it! The bear is all prepared for adding the new electronics.
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