These steps cover the current (2017-and-later) kit. For the older kit, skip to the next page.

Some soldering steps take place close to pieces of the case. Be very careful where you set your soldering iron so as not to damage the plastic parts! Also watch out for flux spatter.

During the soldering and assembly process, certain parts will become “tethered” together by wires…always pick up and move these parts together, don’t let pieces hang by the wires…this could damage parts or solder joints.

Prepare Wires

In the plastic baggie accompanying the thermal printer should be two cables, a bit over a foot long. The power cable has two conductors: red and black. The data cable has three conductors: green, yellow and black.

Cut the red/black power cable in half. This cable has a different plug at each end. We want to keep the wider of the two plugs for the printer; the other can be discarded or tossed in your spare bits drawer.

The data cable (green/yellow/black) is NOT cut, only the power cable!

Use wire cutters to clip the side “wings” off the plug at one end of the data cable.

Do not cut any of these wires! Just trim the plastic.

Next, grab the female/female jumper wires and cut off the connector at one end of each of the following colors:

  • 2 Black
  • 1 Red
  • 1 Yellow
  • 1 Green
But my kit didn’t come with any female/female jumper wires!

You might have the older (pre-2017) version of this kit. Skip to the next page for wiring directions.

After cutting, you should have:

  • A three-conductor (green/yellow/black) data cable with plugs at both ends, about 14 inches long.
  • A two-conductor (red/black) power cable with a wide plug at one end, about 7" long.
  • Five jumper wires about 6" long, each with a female connector at one end.

Prepare Button

Don’t be confused by the colors here. This sequence is three of the jumper wires, not the serial data cable!

Looking at the back of the button, with the pins arranged in a “smile,” the functions from left to right are:

  • LED +
  • NC (Normally Closed)
  • NO (Normally Open)
  • LED –

Using finger pressure or small pliers (gently!), smoosh the last two pins (COMMON and LED –) close together. We need to loop a single wire through both of them…

Strip about 3/8" of insulation from the end of three of the jumper wires: BLACK, YELLOW and GREEN. Twist the ends a bit to keep the strands from fraying.

Do not do this with the serial data cable! Use the one-sided jumper wires.

Loop the BLACK wire through the LED – and COMMON pins, bend it back on itself and solder.

This is a tight squeeze for the wire, like threading a needle. It may help to turn the wire a bit while passing it through, to keep the strands from fraying. It may take a few tries…you can remove the wire, re-twist it, and try again.

Repeat with the GREEN wire on the LED + pin and the YELLOW wire on the NO (Normally Open) pin.

The NC (Normally Closed) pin is NOT CONNECTED.

Fish the three wires through the button hole on the top case piece, press the button into place and secure with the included nut.

There is no front or back side for the top piece…you can insert the button either way.

Prepare DC Jack

There are three “legs” on the DC jack, but we’ll just be using two of them.

The large center leg corresponds to the power supply tip, which will be +5V.

The “outer” of the two small legs is the power supply ring (ground).

The “inner” small leg is not connected.

Strip about 1/4" insulation from the red and black wires on the power cable and the one-sided jumper wires.

Twist the wires a bit to prevent the strands from fraying.

Twist the two red wires together, feed through the large center leg (+) and solder in place.

Repeat with the two black wires through the “outer” small leg (–).

Remember, the “inner” small leg is not connected.

Fish the connector and wires through the DC hole on the back piece of the case (this the part with the etched Adafruit logo) and press the jack into place.

Secure the DC jack from the other side with the included nut. You’ll need to fish the wires through this to get it into place.


Once the jack is in place, solder the 4700uF capacitor to the + and - terminals. This will help keep the voltage stable when the thermal printer is operating.



That’s it for soldering! You can unplug your iron now.

This guide was first published on Apr 12, 2013. It was last updated on Sep 21, 2023.

This page (Soldering) was last updated on Feb 20, 2017.

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