Soldering instructions for Rev. C Boards
These are the board with all through-hole components.
This is the sequence I use to build the unit. Because of the way that the components are laid out, I found this order to be easiest. There are five sections of soldering, and then mechanical assembly. Follow the order in the table in each section from top to bottom. If you got your unit as a kit, then the parts have been bagged by section.
General Notes
Images show the components placed in each step, on the side they are placed. Of course, they are soldered from the other side.
Components should be snug against the board, and the leads on the other side trimmed tight after soldering. This is especially important for the components placed in step 1, which will eventually be covered by the compute and display boards.
The board has large ground areas, which makes soldering component leads that connect to ground a little more difficult. I use a higher soldering iron temperature for these. They are called out in the images with red arrows.
Step 1
| Qty | Device | Value | PCB Side | PCB Label |
|---|---|---|---|---|
| 1 pair | pin header | 1x12, 1x16 | bottom | |
| 4 | resistor | 10kΩ | bottom | R9, R10, R11, R12 |
| 3 | diode | 1N4004 | bottom | D7, D8, D9 |
| 2 | resistor | 10kΩ | top | R13, R14 |
Be sure these male pin headers are the short ones, on the bottom, and in the correct set of holes. The short side pins should poke through the PCB to the top side, and be just inside the white outline. Refer to the photo - if you solder them in the wrong way, unsoldering them is a bear!
Getting the pin headers flat against the PCB can be fiddly. Try tacking one pin at one end with just a little solder, then heating it again while pressing the middle of the header snug. Careful not to touch the pin being heated!
Try to keep all the bottom side resistors and diodes flat against the PCB - they need to clear the compute board which will be below them.
Double check the orientation of the diodes: Two go one way, one the other.
If you got the kit, the diodes are in the anti-static bag, with the other semiconductors.
Step 2
| Qty | Device | Value | PCB Side | PCB Label |
|---|---|---|---|---|
| 1 pair | pin header | 1x12, 1x16 | top | |
| 2 | resistor | 100kΩ | top | R17, R18 |
| 6 | resistor | 1kΩ | top | R1, R2, R3, R4, R15, R16 |
| 2 | LED | red | top | LED symbol w/R |
| 2 | LED | green | top | LED symbol w/G |
| 1 | pin header | 1x2 | top | LED Power |
| 1 | shunt | 2 pin | ||
| 1 | capacitor | 330nF | top | C1A |
These male pin headers are the longer ones. This time the long side goes through the PCB from the top to the bottom, leaving just the short pins up on top. These pins will be closer to the top of the edge of the board than the previous ones, and offset from the silkscreened board outline on the top of the PCB.
Double check that you've go the LEDs inserted in the correct orientation: The flat edge should line up with the flat edge printed on the PCB. Try to get the LEDs snug up against the board.
If you always want the LEDs lit, then you can just solder a small wire across the LED Power pads. This is much easier than soldering the header.
Otherwise solder the 1x2 header. Short side goes in the board. Holding this will burn your fingers, so stick the long pins in a cork, and use the cork to hold it to the board as you solder the first pin. After it is soldered, put the shunt on it.
Step 3
| Qty | Device | Value | PCB Side | PCB Label |
|---|---|---|---|---|
| 4 | resistor | 2.2kΩ | top | R5, R6, R7, R8 |
| 2 | resistor | 33kΩ | top | R19, R20 |
| 6 | diode | SD101A | top | D1, D2, D3, D4, D5, D6 |
| 1 | capacitor | 100nF | top | C2A |
Double check the orientation of the diodes: Some go one way, some the other.
If you got the kit, the diodes are in the anti-static bag, with the other semiconductors.
Step 4
| Qty | Device | Value | PCB Side | PCB Label |
|---|---|---|---|---|
| 6 | transistor | 2N2222, NPN | top | T1, T2, T3, T4, T5, T6 |
| 1 | PTC fuse | bottom | ||
| 1 | encoder | top | ||
| 1 | linear regulator | 78M33 | bottom | |
| 1 | DC power jack | 5.5mm od, 2.1mm id | bottom |
If you got the kit, the transistors and linear regulator are in the anti-static bag, with the other semiconductors.
Double check the transistor orientations: some go one way, some the other. Try to solder them as close to the board as they will naturally go.
The washer and nut on the encoder shaft are not used in the build. Remove them if they are one the shaft. Make sure the encoder is flat up against the PCB when you solder it.
Bend the leads of the linear regulator to about 60°. You don't want the device to lie flat on the PCB - but instead be at angle so there is air flow around it. See photos. The two power rail leads, pointed to by the purple arrows, are harder to solder because the device dissipates heat. I do these on a higher soldering iron setting, like the grounds.
Test
Check for shorts to ground with a multimeter. You can use the big ground ring as one point and make sure:
- None of the other big rings or small rings are shorted to ground.
- For each of the 6 diodes, D1 ~ D6 from step 3, one side should be shorted to ground, the other not.
- For each of the 6 transistors, T1 ~ T6 from step 4, one of the three legs should be shorted to ground, the others not.
You can now power up the board with any 12V, center positive power supply you have around.
Use a multimeter and test the following:
- There is an unfilled capacitor symbol on the back, C1B. It should have about 11.5V across its pads.
- There is an unfilled capacitor symbol on the back, C2B. It should have about 3.3V across its pads.
Those capacitor pads will remain unpopulated. They are there for use with a different power regulator.
Power off the board and keep going...
Step 5
| Qty | Device | Value | PCB Side |
|---|---|---|---|
| 1 pair | pin header sockets | 1x12, 1x16 | bottom |
| 1 | compute | Feather M0 | bottom |
| 1 | display | Feather OLED | top |
Mate the header sockets to the pins on the bottom of the board (the first set you soldered). Place the Feather M0 board, upside down, on them. There should be plenty of clearance between the board and the components mounted on the bottom side under it.
Solder tack two opposite corners. Check that the whole assembly is snug and level. Then solder all pins. The ground pins are marked in the image, but these probably don't need a higher solder iron temperature.
Flip the board over and place the OLED on the short header pins. Leave the protector on the OLED - to protect against flux and solder bits. These are the second set of pin headers you soldered. Besure all the component leads under the board have been trimmed nice and close, so that nothing is touching the underside of the OLED board.
Note: The OLED board is going to sit offset from the board outline silk screened under it.
Solder tack two opposite corners. Check that the whole assembly is snug and level. Then solder all pins.