nw2s::b Panel Board Assembly Guide – Step 1

Overview

The following steps should guide you through the panel board assembly process. This is the easier of the two boards, so may be the best place to start.

This kit is not intended for beginners. While the circuits are not individually complicated, the volume of work is significant and requires concentration and attention to detail throughout the process. With other kits, if you accidentally swap a 1k resistor for a 10k, you just have to undo them and move on. With this kit, you’ll be 16 or 32 resistors in before you realize you’re in trouble!

I’ve purposely priced the assembled units cheap enough on top of the kit price so that if you doubt your abilities at all, you should consider if it’s worth your time and trouble to use this as a learning experience.

I won’t go into any detail about how to solder since there are plenty of tutorials out there. One of the better I’ve seen is from Adafruit.

Click here to download the schematics and bill of materials in PDF format.

Tools and Supplies

Required:

  • Nice soldering setup and the skills to use it!
  • Lead-free solder – make the switch – for the kids!
  • Quality multi-meter
  • Lead bender
  • Small flat screwdriver for tuning
  • Diagonal cutters
  • CV generator (ideally something bipolar)
  • 2.5mm hex driver
  • 5/16″ socket driver
  • Cynaoacrylate glue (super glue, aka kragle)

Recommended:

  • Panavise PCB holder
  • Nut driver
  • Oscilloscope
  • Small square file

Please note that these boards are somewhat tight, and there are a total of 127 components that need to line up properly with holes on the panel, so it’s important that you assemble in the correct order and do everything possible to line up the components properly.

Note that some of the pads may be closer than you are used to dealing with. USE ONLY AS MUCH SOLDER AS NECESSARY! As long as you get good flow, a little less solder than optimal is better than a little more solder than optimal. Go easy with it. Use a very small gauge solder and a relatively fine tipped soldering iron.

Pay close attention to which side of the board the different components go on. Specifically some of the board-to-wire connectors go on one side, and some go on the other.

Bill of Materials

First, read through the instructions. Every time I mess up, it’s because I didn’t read the instructions first.

Second, gather your materials. The following table is the bill of materials for the panel portion of the build.

PART QTY DESCRIPTION CODE
1 panel PCB P55888
1 panel nw2s::b
D1 – D24 24 5.1V zener diode 5V1
RIN1 – RIN12 12 100½ 1% resistor brown black black black brown
D25-D32 8 3.3V zener diode 1N 52 26B
RDIN1 – RDIN8 8 10k½ 1% 1% resistor brown black black red brown
RDZ1 – RDZ8 8 100½ 1% resistor brown black black black brown
RD1 – RD16 16 1k½ 1% resistor brown black black bown brown
RSD, R1 2 160½ 1% resistor brown green black black brown (light green body)
RBT 1 1k½ 1% resistor brown black black bown brown
BEATCLOCK 1 1 x 16 pinheader
POWER 1 2 x 5 pinheader
ANALOG_IN 1 1 x 12 pinheader
GATE_OUT 1 1 x 8 pinheader
CVHDR1 1 1 x 6 pinheader
CVHDR7 1 1 x 10 pinheader
JP1 – JP4 4 1 x 4 pin receptacle
MNT1 2 1 x 2 pin receptacle
AUDIO 1 1 x 6 pinheader
4 M3 x 0.5 socket cap screw
4 25mm standoff
8 M3 nylon washer
AIN1 – AIN12 12 switched 3.5mm jack
DIN1 – DIN8 8 switched 3.5mm jack
GATE1 – GATE16 16 switched 3.5mm jack
CV1 – CV16 16 switched 3.5mm jack
DAC1, DAC2, NOISE 3 switched 3.5mm jack
DSW1 – DSW8 8 miniature SPDT on-off-(on)
PIN1 – PIN12 12 100k 9mm linear potentiometer
C1, C2 2 47µF electrolytic capacitor
SW1 1 momentary tactile switch
LEDSD 1 amber LED
LEDBT 1 bright blue LED
LED-A1 – LED-A16 16 bright blue LED
LED-D1 – LED-D16 16 bright green LED
LED1 – LED16 16 red LED

Resistors, Diodes

Begin with the resistors and diodes – the small axial components. All of these go on the top side of the PCB.

01-throughhole

Diodes

There are two sets of diodes.

The 5.1V zeners are organized in 12 groups of two diodes plus one resistor and protect the analog input circuits from over and under voltage.

The 3.3V diodes are 8 single diodes paired with two resistors that are used to protect the digital inputs from overvoltage.

The diodes are each in a separate anti-static bag and marked with their values. If you lose track of which are which and can’t read the writing on the tiny packages, then you’ll have to rig up a resistor and diode network on a breadboard and measure the voltage across the zener. Make absolutely sure you get them in the right direction and position.

Analog Input Resistors

For the zener diodes to work, they need to act as voltage dividers against something else. There are 12 100Ω resistors (RIN1 – RIN12) alongside the zeners to serve this purpose.

Beatclock LED Resistor

Since there is only one clock LED on at a time, they are configured as common cathode with a single 150Ω resistor at R1.

03 beatclock resistor-processed

Digital In Pull-Down Resistors

The digital inputs in an unconnected state require pull-down resistors to prevent them from floating up to a positive state. RDIN1 – RDIN8 are all 10kΩ pulldowns.

Digital Input Resistors

Like the analog inputs, the digital inputs are also protected from overvoltage with a zener. Like the analog inputs, the zener needs a resistor to act as a voltage divider against. There are 8 100Ω resistors labeled RDZ1 – RDZ8.

Digital Output Indicator Resistors

The green output indicators are super bright green and require a fairly high resistance value to keep from blinding anyone staring in the general direction of the ‘b. RD1 – RD16 are all 1kΩ resistors.


Note – these are particularly close pads – go easy! Also, the screen print for these place them on the bottom. That is a mistake. They need to be on the top just like all of the other resistors.

Bluetooth and SD Card Indicator Resistors

RBT is a 1kΩ resistor and RSD is 150Ω

Headers

The next step are the headers. With the goal being to add components of increasing profile heights, the pin headers should all go on fairly easily, standing up on their own. Just make sure they go on straight and in the right direction. These are REALLY hard to undo if you do them wrong. Just do one on each end and verify that it’s straight before continuing.

Power Header

The panel PCB receives power from the main PCB through this 10 pin header. The kit includes only 12-pin 2-row connectors, so you will need to use your diagonal cutters to lop off one of the pairs of pins from the end. If, like me, in the process of cutting two off the end, the whole thing breaks, there should be plenty of spare single-row headers that you can double them up as 2 1×5 headers.

This header faces downward.


This header does not follow the Eurorack standard! It should only be connected to the corresponding header on the mainboard.

08 power header

Beatclock and Analog In Header

The beatclock header is a 16 pin header, so you will need to take a 20 pin header row and cut four off with your diagonal cutters. Save these four as we’ll use them in a subsequent step.

The analog in is a 12-pin header, so choose one of the 20-pin units and cut 8 pins off. Save this 8 pin connector as we’ll also use it shortly.

These headers face downward.

09 beatclock analogin headers

Digital In and Digital Out Headers

The digital in header is an 8 pin header. You can use the left over 8 pins from the analog in step earlier.

The digital out header is another 16 pin header. Use a fresh 20-pin and trim four off.

These headers also face downward.

10 digital in out headers

CV Out Headers

Continuing on, the CV headers are next. They are grouped into a set of 10 and a set of 6. Use any left over header pins as you have them and clip new ones when you need them.

11 cv header

Audio, Reset, Bluetooth, and SD Headers

Then comes the audio, bluetooth, SD status, and reset header. Same as before.

12 audio header

Standoffs

Next comes the standoffs. We will want to do these before placing the high-profile electro-mechanical pieces. We are using 4 M3 hex head bolts to hold the standoffs in place with nylon insulating washers. DO NOT SKIP THE WASHERS! The top of the PCB has a +5V plane, and if the steel bolts wear through the solder mask, then you’ll be shorting the +5V signal and that will not be good.

The two insulating washers near CV1 and CV15 need to be trimmed as shown and placed diagonally in order to fit in between the other components. You can use your diagonal cutters to make the cuts.

14 standoffs 1

LED Driver Headers

This set of header receptacles accepts the pre-assembled Adafruit PWM LED driver board. It’s important to get these as straight as possible during assembly to ensure the pins line up.

The spacing on the power pins does not match the standard 2.54mm spacing, so you will need to use two single pin receptacles. Since there are no 1-pin receptacles available, simply pull out one of the pins from two of the 2-pin receptacles and use that as shown below.

12-leddriver-3

Once the male headers are on the driver board, you can put the receptacle headers onto the driver board. Then assemble the driver and panel PCB together so that the pins line up and everything fits snugly. Use a rubber band to hold the assembly together and solder the receptacle pins.

13 led driver header

Power Filter Capacitors

The +5V and +3.3V rails are isolated from ground via a 47µF capacitor which will help filter out any noise and keep the rail stable on this PCB.

The stripe indicates the negative side of the capacitor and goes AWAY from the ‘+’ marked on the PCB. The longer lead goes towards the positive side.

Electromechanical

Four corners

To properly align the electromechanical parts, we first need to establish a stable reference point. To do this, remove the hex nuts from and place CV2, CV16, AIN1, and AIN6. Place the panel over those four, and to hold them in place, use a rubber band.

When placing the jacks, please note the placement as printed on the PCB. If you’re not paying attention, in some cases the component may fit in multiple directions, but the outline indicates proper placement.

Note: In this tutorial, I am using one of the prototype acrylic panels rather than the aluminum ones. I am simply doing this for illustrative purposes so you can see what’s going on underneath. The aluminum will serve the same purpose when you are doing the assembly.

15 four corners

Jacks

Next, remove the nuts from and place each of the remaining jacks, paying attention to the silkscreened placement guides. Then replace the panel on top and loosely tighten nuts onto the four that are now soldered in place (CV2, CV16, AIN1, and AIN6). The remaining jacks will now be stable enough to solder.

GATE2’s outer leg will need to wrap around resistor RD1 just a little, but it’s long enough.

16 jacks

Pots

The potentiometers theoretically snap in so that they hold themselves. In practice, however, you will need to bend the snappy legs out just a little so that they stay. Snap them all in, flip it over, and solder. There are three contacts that actually work and two that are for grounding and support. Go easy on the solder for all of them as there are a few contacts that are close in a couple of spots.

17 pots

Switches

The most important thing about the switches is that they need to be positioned correctly. The momentary action should point towards the input side of the board (the left).


Note that you cannot trust the markings on the switches to be the sole indicator of which way they should face! Test each switch individually to ensure that the momentary side is facing the correct way.

Mounting the switches is much like mounting the jacks. Place them on the board, replace the panel. Loosely tighten four or so nuts on jacks near the items in question, double check the direction, triple check the direction, flip it over, and solder.

18 switches

Reset Switch

Okay, this one’s easy. The leads are long enough to bend to hold it in place. Just make sure it’s vertically square so it fits through the hole in the panel.

19 reset

LEDs

The process of putting the LEDs in is that of slotting them in to the holes, letting them settle, putting the panel back on, flipping it over, making sure that each one is completely resting on the holes, soldering, and trimming.


THE ABSOLUTE MOST IMPORTANT THING IS TO GET THEM IN THE RIGHT DIRECTION! And they are not all in the same way, so very important! Pay attention!

LEDs generally have two indicators as to polarity. The long lead is the positive lead and the flattened side of the lens is the negative. The silkscreen is supposed to indicate the flattened side, but with the plated holes, you just can’t make it out, so I’m going to run through them quickly here:

  • Beat Clock LEDs: Red LEDs, flat side away from the rest of the board, long pin to the inside of the board.
  • Digital Out LEDs: Green LEDs, flat side away from pots, long pin toward potentiometers.
  • CV Out LEDS: Blue LEDs, flat side away from pots, long pin toward potentiometers.
  • LEDSD: Amber LED, flat side toward outside of board, long pin toward inside.
  • LEDBT: Blue LED, flat site toward inside of board, long pin toward the outside.

panel layout

Here you can see them settled into position prior to attaching the panel:

20 leds A

When you flip it over, it’s easy to make sure all of the pins are facing the correct direction. Also make sure they are all poking through the panel at the correct depth. Then solder and trim leads.

20 leds B

Done.

Then bask in the glory of having the panel complete! We’ll do the mainboard next and the SD card and LED driver boards last.

21 panel

Note: In reality, you shouldn’t put all of the nuts and knobs on just yet. If you need to debug anything later, it’s a lot easier to get the panel off if you only attach four nuts – enough to just hold it at the corners. Also, leave the protective plastic layer on the panel until you’re done. Sure looks nice tho!