PX Series Calculator Assembly

Let me start by saying that this is not a soldering tutorial.
There are plenty of great tutorials online like:

Everyone has his style for building/soldering things. This is just my way of building/assembling the calculator.


Let's begin:

Step 1.0

Start by soldering the shortest components.

  • Resistors R1 and R2
  • Capacitors C1, C2 and C3
  • Programing header J1
  • 32.768KH Crystal XTAL

Step 1.1

  • If the capacitors are too tall, they might not allow the display to sit evenly on top of the microcontroller, so bend them slightly to one side.
  • It is good practice to solder the crystal can to the PCB.

Step 2.0

  • Set the microcontroller completely flush against the board.
  • Make sure the microcontroller notch or dot (pin 1) is aligned with the pcb markings.

Step 3.0

  • Solder the rest switch. RST
  • Solder the CR2032 Battery holder.

Step 4.0

  • It is easier if you mount all switches on the pcb all at once then flip over the pcb and place it on a even surface.
  • Push on the back of the pcb to force all switches even.
  • (Some people find it easier to use the top aluminum panel as a guide.)

Step 4.1

  • Solder only one pin of each switch
  • Push on the back of the pcb to force all switches even.

Step 4.2

  • Visually inspect that the buttons are completely straight and flush to the pcb.

Step 4.3

  • Solder a second pin of each button.
  • Visually inspect that the buttons are completely straight and flush to the pcb.
  • Continue to solder all oins on the buttons.

Step 5.0

  • Next thing to solder is the speaker.
  • Watch the polarity.

Step 6.0

  • Solder the 9 pin male header to the display.
  • Make sure the header is solder to the display with the short side, flush and at a right angle.

Step 6.1

  • Place a strip of double sided tape on top of the microcontroller.

Step 6.2

  • Place the display directly on top the the microcontroller.
  • Make sure it is sitting straight and flush to the microcontroller.
  • Once you are sure is it properly sitted, continue to solder the display to the pcb.

Step 7.0

  • Now it's time to test it.
  • Insert a 3V CR2032 coin battery.
    Make sure the positive side of the battery is facing up.
  • You should be greeted with a HELLO.

Aluminum Panels Assembly:

Before we start...

Make sure ALL pins are cut flush.

It is very important that all pins/wires are cut as short as possible.

Step 1.0

The parts to assemble the panels:

  • Top and bottom aluminum boards.
  • Acetate Separator
  • 4 brass posts
  • 4 M2 screws 5mm in length
  • 4 M2 screws 7mm in length
  • 4 8 1mm in height washers

Step 2.0

Start with the bottom aluminum panel.

  • Place the bottom Aluminum panel down.
  • Add on top the acetate separator.
  • Add the washer.

Step 2.1

This is how it should look.

Step 3.0

  • Now it's time to place the pcb.
  • Add another 1mm nylon washer.

  • *Note 1: If you want the buttons to protrude above the aluminum panels more, replace the 1mm washers with electric tape or another insulating separator.
  • *Note 2: Newer kits with the PCB labeld "Universal board 1.1" do not need the 1mm washers.

Step 4.0

  • Screw the four 8mm brass posts.

Step 5.0

  • Carefully, cover the calculator with the top board.
  • Screw the board with the 5mm screws.

Step 6.0

  • Remove display protective cover.
  • Enjoy your new calculator!

3D Printed Bumper Assembly:

3D Printed Bumper...

This is the Bumper.
It will protect the aluminum panels sides from an accidental drop.

Step 1.0

Make sure the bumper is clean.
Remove any debris or supports left from the 3D printer.

Step 3.0

Gather all parts.

  • 3D Printed Bumper.
  • Fully Assembled PX Calculator
  • Back and front aluminum panels
  • Acetate film
  • Hardware: screws, washers and brass posts
  • 3D printed Coin Battery Holder

Step 4.0

Place the PCB inside the Bumper.
Check where the battery location is.
It should fit snuggly.

Step 5.0

Flip the bumper and place the Acetate film.
This film will prevent the pcb solder side from touching the aluminum back panel.
Note: The four bottom washers are not need when using the Bumper.

Step 6.0

Place the bottom aluminum panel.

Watch out for the orientation, so that the lettering on the bottom is correct.

Place the four long screws and carefully flip the calculator. Take care so that the screws don't fall while flipping the calculator.

Step 7.0

Place the four washers.
One washer on each screw.
Using tweezers really helps.

*Note: Newer kits with the PCB labeld "Universal board 1.1" do not need the 1mm washers.

Step 7.1

This is how it should look.
One washer on each screw.

Step 8.0

Screw the four brass posts.
Using tweezers might help.

Step 8.1

This is how it should look, with the 4 brass posts.

Step 9.0

Now, carefully place the top aluminum cover and screw it down with the four short screws.

Step 10.0

Place the battery in the 3D printed holder.

Step 10.1

Now, carfully insert the battery holder in the calculator.

Step 11

That's it.
You have finised.

Enjoy your calculator!

Optional: Attach the rubber feet.


Part List

Part Value Description
C1, C2 0.1µf Decoupling Capacitor
C3 0.1µf Speaker impedance
U1 ATMEGA328P Microcontroller
J1 6 pin female headers PI Programing header
BAT Battery Holder CR2032 Battery Holder
XTAL Clock Crystal 32.768kHz Clock
R1 10KΩ Reset pullup resistor
R2 10Ω LCD backlight resistor
BTN's 6x6mm tactile switch 7mm height Key buttons
RST 6x3.5 mm tactile button Reset button
DISP Display 192X64 LCD Display