Introduction: How to Solder Your OpenXC Retro Gauge

In this Instructable, we will teach you how to solder your very own OpenXC Retro Gauge. For complete instructions and information about OpenXC and the Retro Gauge, checkout openxcplatform.com and openxcplatform.com/projects/retro-gauge.html

For the purposes of this tutorial, we assume that you know how to solder. If this is not the case, fear not since there are a lot of great soldering tutorials out there. Here is one of our favorites:

https://learn.sparkfun.com/curriculum/36

This is a good video tutorial on how to solder surface mount components:

Soldering Tutorial - Surface Mount


Materials Needed:
- Soldering Iron
- Tweezers
- Solder
- Solder wick
- Gauge PCB and BOM

When soldering on the components onto the PCB, there is really no particular order that is required. For this tutorial we decided to start with smallest components and work towards the larger ones.

Here is a timelapse of the PCB being assembled to give you an overview:

Step 1: RGB LEDs

For the Retro Gauge, we used the Cree RGB LED, part number CLVBA-FKA-CAEDH8BBB7A363. These LEDs have a pin mark (triangular notch) on the bottom left corner. It is important to make sure that when you solder your LEDs to the PCB, that the mark matches the bottom left corner on the PCB (left of the power silkscreen).

Step 2: 100 Ohm LED Resistors

These components are pretty straightforward to solder on to your board.

1) Apply a small amount of solder to one of the pads
2) Grab the resistor with a pair of tweezers and position it over the pad, centered in the correct spot.
3) Heat up the pad with the soldering iron and place the resistor on the pad
4) Once you see solder flow over the resistor, remove the iron and repeat for the next 5 resistors

Step 3: 74HC595 Shift Registers

Orientation is key for this component. On your PCB, you will note that each shift register has a notch on the silkscreen footprint which indicates the orientation of the integrated circuit (IC). Make sure that the white bar on top of each component is oriented over the white notch on the PCB.

There are a number of methods for soldering ICs with pins that are close together. For people with a steady hand, We recommend that you solder each individual pin to its respective pad. However, sometime you have had just too much coffee and your hands will not stop shaking. If this is the case, choose the BLOB method!

1) Place a small amount of solder on one pad, heat it up and attach the IC to the pad.
2) Place a blob of solder over all of the pins 
3) Using the solder wick and a soldering iron, heat up the solder wick over the pads and remove the excess solder

If done right, your shift register should be attached to the PCB and there should be no solder jumping between two different pads.

For more information about this method, checkout this tutorial: https://www.sparkfun.com/tutorials/96

Step 4: 220 Ohm 7 Segment Display Resistors

Same steps as before:

1) Apply a small amount of solder to one of the pads
2) Grab the resistor with a pair of tweezers and position it over the pad, centering the component between the two pads.
3) Heat up the pad with the soldering iron and place the resistor on the pad
4) Once you see solder flow over the resistor, remove the iron and repeat for the next 15 resistors

Step 5: Two Digit 7-Segment Display & Arduino Mini Pro

1) Place the two 9-position, one 6-position, and two 12-position headers into the appropriate locations

2) Insert the two digit 7-segment display into appropriate location

3) Break off 2 12-segment pins and 1 6-segment pin array from the break away header

4) Place the headers into the appropriate locations and place the Arduino Pro Mini on top

5) Flip the PCB over and solder one pin on each header

6) Make sure that each header is flush and perpendicular to the PCB and solder the remaining pins

7) Flip the PCB back over and solder the remaining pins on top of the Arduino

Step 6: FTDI Header

1) Break off a 6-segment pin array from the remaining headers
2) Insert the header from the bottom of the PCB (The shorter end of the header should go through the PCB)
3) Make sure the header is flush and perpendicular to the PCB and solder the header in place

Step 7: Stepper Motor

1) Insert the stepper motor from the back of the PCB
2) Press the stepper motor lightly so that the pin slightly protrude from the front of the board
3) Solder the 4 pins on the motor to the PCB

Step 8: Congratulations!

Plug the FTDI PCB into the 6-pin header with the back of the FTDI board facing the motor. The silk screen labels on the FTDI PCB should match the Retro Gauge PCB. Once everything is connected, flash the Retro Gauge firmware onto the board. Congratulations, you have just soldered and flashed your first Retro Gauge PCB!