This is a quite straightforward build with only through hole soldering and relatively big parts to assemble.
Do this before building this module:
Check that you have all components.
Front and Back PCB
18x mono switched Thonkiconn jack sockets with knurled nuts.
6x illuminated switches with green marking on the negative leg on the LED.
2x 1×40 pin male header, 2.0 mm pitch.
3x 1×16 pin female header, 2.0 mm pitch.
Gather all the tools needed (see lists below).
The tools needed for this build are:
Soldering station or soldering iron.
High quality solder (lead free recommended).
Fine tipped side cutters.
1 mm flat screwdriver for calibration.
Recommended accessories:
PCB holder (makes life much easier).
Knurled Nut Driver Tool (for tightening jack socket nuts).
Multimeter.
Got everything? Let’s get on with it!
1. Preparing the back PCB
The back PCB comes with break off tabs from manufacturing. Use a pair of pliers and break them off carefully. With the tabs broken off, the back PCB looks like this.
2. Preparing pin headers
These are the pin headers that come with the kit. To prepare them for assembly, push the male headers into the female headers and break off the excess so you get three sets of 16 pin connected male and female pin headers.The assembled headers should look like this.
3. Soldering the pin headers
Place the headers in between the front and back PCBs. Make sure that the Female headers are facing towards the front PCB and the Male headers face towards the back PCB. Also make sure that the back PCB has the power connector and switch side facing outwards, and the front PCB has the silkscreen for the jacks and switches facing outwards. Start by soldering one pin per header and make sure that the headers lie flush with the PCBs and everything is nicely straight and aligned. Then solder the rest of the pins.When all the header pins have been soldered, you should be able to pull the PCBs apart and find the female headers soldered to the back of the front PCB and vice versa.
4. Switches and jacks
Before placing the switches on to the front PCB, note that the negative LED pin is marked with green paint on the side of the switch. On the bottom of the switch there is also a small plus and minus indication, and the minus should align with the green paint.Place the switches on in their corresponding places on the PCB, making sure that the green painted pins align with the minus symbol on the PCB.When all switches have been placed on the PCB, double check that the green painted pins are all facing towards the bottom of the PCB as shown in the image.Place all the jack sockets in their corresponding places as shown in the image.Now place the front panel on to the jacks and switches and screw on all the jack nuts. Carefully hand tighten them to secure the front panel, and make sure that both the switches and jacks are sitting flush with the PCB. Flip the assembly over and solder all the pins for the switches and jacks.This is what the front PCB should look like after the switches and jacks have been soldered.Finally cut off the excess of the pins for the switch LEDs, as they could possibly be long enough to reach the components on the back PCB.
5. Final assembly and power up
Find the white dots on the front and back PCB, and align the pin headers with each other.Carefully push the pin headers together and make sure they are all fully seated. Tighten all the jack socket nuts with an appropriate tool that doesn’t scratch the front panel. After you’ve done that the module is assembled!
Before powering the module, please measure resistance on the power connector. There should be 100-200 kOhms between Ground and +12V and 50-100 kOhms between Ground and -12V (red stripe side).
5. Calibration
The BIAS TRIM trimmer potentiometer adjusts a common DC offset for the VCA control voltage inputs on all channels. The purpose of this is to be able to fine tune if there is a little signal bleed when the channels are muted. The trimmer also affects the linearity of the output in relation to the inputs, so if you want to mute V/OCT signals the calibration is extra important.
To make a rough calibration: – Set all channels to MUTE on the back of the module. – Connect a square wave from an oscillator to the input of channel 1. – Turn the channel off by pressing the switch once, the LED will turn OFF. – Connect the output to a mixer or output module and monitor its output with headphones. – Adjust the trimmer until you start to hear the signal bleed through. Then adjust it back the other way so you don’t hear the bleed through any more.
To make a precise calibration: – Set all channels to MUTE on the back of the module. – Connect a 1.00V voltage to the input of channel 1. – Turn the channel on with the switch, the LED will be ON. – Connect a multimeter to the output of channel 1. – Adjust the trimmer until the output voltage matches the input voltage, i.e. 1.00V.
