Take your scale out of the box - it's hardware hackin' time!
We're going to begin by popping the front faceplate off.
Run a spudger along the top edge of the scale's faceplate, from right to left. You should feel the faceplate pop as you run it along.
Once the spudger reaches the end of the faceplate, it should pop off.
Then, remove the front faceplate from the scale.
Flip the scale over - at the end of the scale are removable rubber feet, pop these out with a flathead screwdriver or a spudger.
Using a spudger, gently pry at the seam between the scale's top cover and the base.
As you go along the edges of the scale, the plastic will pop. Do not force the spudger in any direction other than sideways - you'll risk breaking the scale's thin plastic cover.
Continue running the spudger along the scale's seams until you've gone completely around the scale. When you get to the front of the scale (near the LCD), you'll be running the spudger towards the bottom of the scale's base.
Slowly remove the cover, tilting it slowly towards the front of the scale.
Do not completely remove the cover - there are wires connected to the front panel
With the cover slightly open, you may notice some wires snagging. With your spudger or a dull screwdriver, move these wires away from the plastic posts so they do not snap when you open the case fully.
Remove the foam adhesive on the right and left sides of the scale. This will let the PCB move around more, giving you more wiggle-room to solder later.
We're going to be soldering to the trace highlighted.
Locate this trace on the PCB - it should be directly above the T28 silkscreen text.
We can not solder to the board until we've removed the solder mask.
Using a flathead screwdriver, scrape off the green solder-mask until you've revealed the copper underneath.
Be careful to scrape up-and-down, instead of left-to-right, so you don't accidentally cut the trace.
With a pair of wire cutters, remove the header plug from the end of the white wire.
Then, using a pair of wire strippers, strip a short (~2mm) length of wire from the end of the white wire.
Tin the copper pad you exposed with the razor by applying a small amount of solder to it. Then, tack the wire to the pad by heating the wire with the soldering iron.
The connection between the white wire and this pad is still fragile. Using kapton tape, or a dab of hot glue, secure the white wire to the back of the board.
Solder the red header pin to the USB V+ pin on the left side of the board.
Then, solder the black header pin to the USB VSS pin.
Check out the right side of the board. There's two red wires below a white box on the PCB attached to the KG/LB button.
Note: On the DYMO M-25 model, this button is labeled G/OZ instead of KG/LB.
Using wire cutters, remove the header pins from a 3-Pin JST-PH cable.
Then, with a pair of wire strippers, strip off a small amount of the rubber sheathing covering each pin.
Solder the white wire from the JST cable to the KG/LB (or G/OZ) pad on the PCB.
Solder the black wire from the JST cable to the GND pad on the PCB.
Before you re-assemble the PyPortal, make sure the connections for the kg/oz button and data pins are still connected.
The rectangular holes in the scale's faceplate are perfect for wires to be threaded through them.
Thread the cables through the rectangular holes in the faceplate.
Then, place the top of the scale onto the metal top plate and re-attach the screws underneath the scale to secure the top of the scale.
On the right side of the PyPortal are two 3-Pin JST-PH connectors. These connectors can be used for analog or digital communication.
Connect the 3-Pin JST-PH connector from the button to D3 on the PyPortal.
Connect the other 3-Pin JST-PH connector for the scale data to D4 on the PyPortal.
We're done! Lets move onto the software to control and communicate with the DYMO scale.