Twilight Zone Robby the Robot pinball Mod

Robby the Robot

Picture of Robby on the playfield.

I decided to put three LEDs into the unit. The first two were to replace the ones already provided (the yellow buttons and the blue 'mouth'). The third would be a way to light up the clear domed helmet.

Opening the robot case.

The first task is to safely open the robot. I studied Martin's pictures of the robot, and tried his suggested method of "levering" the legs apart. This worked partially, but the main body's glue joints did not come apart. I then used a miniature screw driver as shown above to pry the body open. Once open, I removed the battery holder, circuit board and speaker, and I glued the case and legs back together.

Hook removed and head opened.

The next step was to figure out a way into the head. I first removed the ornament hook at the top by simply pulling it out. I had tried unscrewing it, but it simply spun. However, I am sure that the initial spinning did loosen it up, and prevented any damage.

I then used a miniature screwdriver in the back to pry the head open. The result is shown above. As can be seen, the center post holds the two parts together, and was glued into place. Trim the center stud and widen the hole so that they two halves fit back together.

From this vantage point, you can finally see that the clear domed helmet is held down by glue tabs deep inside the head. Use a miniature screwdriver to clean these out, and the helmet should come out.

The 'face' of Robby without his clear helmet. This latter part is

glued into the two holes at the top.

While Robby had his face shield off, I decided to repaint him slightly to match the playfield image (see above). This meant adding some red accents with my favorite detail paint brush: a sewing pin.

Robby with his makeup on. Compare to the playfield image above.

Much of my painting on playfields is done with this blunt sewing pin.

Once this was done, I decided to light up the helmet by drilling a hole near the top back of the face, and putting an LED inside the head. I used a white LED that was filed flat on front and back side.

LED inserted into the head to light up the helmet.

Next, I drilled a small hole into the post of the head so that I could put in a screw to hold the two halves together. A washer is needed due to the size of the hole in the head disk. I then selected a white (not blue) wide angle LED to face towards the player to produce the brightest spot of blue in the mouth plastic. One leg of this LED was held down by the washer, and then the body of the LED was glued into place.

Finished head disk assembly. A screw is used to hold the LED

down, and to join the two halves of the head.

After this, I prepared the body (now mainly empty) by glueing a bright yellow LED (a gift from Martin) that faced forward into the chest openings.

The two halves of Robby ready to come back together.

I received a bracket for this robot courtesy of Cliffy. He made these for the original Masudaya robot mod.

The completed robot, mounted on a bracket courtesy of Cliffy.

The disconnect is made using IC socket pins.

Note the other color accents on the robot's body.

I decided to wire the three new LEDs to the three lamps that are next to the image of Robby on the playfield. They happen to be on the same column of the lamp matrix, which makes it convenient for wiring. I only needed four wires for the three LEDs. I prepared a harness made from ribbon cable with a connector as I usually do to allow disconnection of the mod.

Wiring Diagram of the LEDs. Wire colors for the lamp matrix

connections are shown.

The lamp column wire is the anode connection, and I put diodes in series (inside the body) to protect the LEDs from reverse voltage. I also put a 51 ohm resistor in series to control the current, but that was placed under the playfield for easy access to change the brightness.

When I went to wire the robot into the playfield, I found out that these three lamps are on a small board. This made it even easier to wire the robot into the playfield as I could remove the board to attach the wires.

Robby installed into the playfield.

Youtube video of the installed robot.

Animated GIF showing the effect of the LEDs.