Soldering (Pre 2017)

These steps cover the older (pre-2017) kit.

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 the T-Cobbler

First we’ll be joining the T-Cobbler board and 26-pin socket.

But my kit didn’t come with a T-Cobbler!

You probably have the newer version of this kit. It’s explained on the prior page.

Normally the Cobbler would have a header soldered to the top, but we’re doing something different with this kit: the socket sits on the underside of the board.
Tack the header in place by soldering just one pin (any will do) on the top side of the board. Notice we’re soldering on the label side for this step.
Check that the header is straight and square. If not, heat the one soldered pin and realign the header.
Once the header is straight, the rest of the pins can be soldered.

It’s normal for a bit of solder to drain or “wick” down the hole being soldered…in fact, this is good and proper soldering technique. But only a little. If you keep feeding solder, the socket holes on the other side will fill in with solder and won’t plug into the Raspberry Pi!
After soldering (and allowing some time to cool), you can test fit the Cobbler on the Raspberry Pi. Gently pry it off with your fingers afterward…more soldering lies ahead…

Prepare Wires

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

These cables are a bit over a foot long. We don’t need that much length inside the case, so we’ll be cutting them in half. Do not throw away the other half! We’ll be repurposing the extra wire in a subsequent step.
The power cable has a different connector at each end. We want to keep the wider of the two connectors for the printer. The small connector at the other end can be clipped off.

The data cable has wide connectors at both ends. One should be left connected, the other can be clipped off and discarded.

If you inadvertently cut the wrong connector off the power cable, you may be able to salvage it using a jeweler’s screwdriver to push the pin sockets out (there’s a small tab on the side that keeps them in place) and replace the connector at the other end.
After cutting, you should have two cables, each about 7 inches long, both with a “wide” connector: one for power (red and black) and one for data (green, yellow and black).

You should also have five loose wires (two black, one red, yellow and green). Keep these for later steps.

The two connectors (one small, one wide) can be discarded.

Prepare Button

This is done using three of the spare pieces of wire, 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 spare 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 spare wire pieces.
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 spare 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.

Wiring Diagram

In the next few steps, we’ll be connecting components to the Cobbler according to the following diagram:

Solder the Serial Data Cable to the T-Cobbler

Strip about 1/4" insulation from the three wires of the serial data cable.

  • Solder the GREEN wire to the RXD pin on the Cobbler
  • Solder the YELLOW wire to the TXD pin on the Cobbler
  • The BLACK wire can go to any GND pin, but the next in line on the Cobbler is especially tidy.

The wires are inserted from the top side of the board and soldered on the underside.

Solder Remaining Wires to the Cobbler

Components that are installed in case pieces are now soldered to the Cobbler. Once these are tethered together like this, they can’t be separated. Always pick up and move these parts together as a set. Don’t let pieces hang by the wires.

The button and power wires are now soldered to the Cobbler using the wiring diagram.
  • RED from DC jack to 5V0 on Cobbler
  • BLACK from DC jack to GND on Cobbler
  • GREEN from button to #18 on Cobbler
  • BLACK from button to GND on Cobbler
  • YELLOW from button to #23 on Cobbler
Once all the wires have been soldered, you can trim any excess on the underside so that nothing accidentally touches the Pi board.
That’s it for soldering! You can unplug your iron now.
Last updated on 2017-04-22 at 08.04.45 PM Published on 2013-04-12 at 11.38.58 AM