Remove the 20mm spacers

Step 16 : LCD (critical step)

Insert the LCD into its footprint on the top of the PCB. Do not solder it yet!

PCB prior rev1.4 :

Cut a piece of wire. You will use it to attach the LCD board to the PCB using solder on the back side of the PCB in the M3 Mainboard holes.

montage-matrix-ctrlr-tutorial-92 montage-matrix-ctrlr-tutorial-93 montage-matrix-ctrlr-tutorial-94



PCB rev1.4 : holes are not metaled , you will use a plastic strap to attach the LCD to the TOP face of the PCB.


Take the front panel and assemble the sandwich using screws. Notice the LCD is loose, so take care. Align the LCD perfectly in the frame, so that you can’t see it over the panel when you look from the sides. Tighten M3 black spacers & screws.


The LCD is held between the front panel surface and the PCB. Use the switches to perfectly align the PCB and front panel. Take your time. Make necessary adjustments, screw/unscrew until it’s perfectly aligned. This is a very important stage and you won’t be able to go back if it isn’t done right.

When you’re confident in your work, solder ONE lead of the LCD connector to bottom side of the PCB.


Again, check the alignment. If it is good, solder another lead. Check again, and so on until the last lead is complete. Once all leads soldered you can setup contrast, not before.

Don’t use to much solder in a first time as desoldering may be very complicated.

Put a solder blob on P15 to hardware connect R/W of the LCD to the ground (jumper).

If you don’t, this would fail the display initialization resulting in solid block like below :


Set up Contrast and Light : turn LIGHT1 clockwise until you see the backlight illuminating. Then turn CTRST1 counterclockwise until you see characters on the display. It will display random information: that’s normal, you haven’t yet soldered in the potentiometers and the arduino’s ADC generates random values.

Step 17 : Potentiometers, Encoder

RV1,RV2 … RV32



Place all of the potentiometers in their footprints, close against the board. Same for the encoder.


Solder one of their snap-in leads (e.g the bottom lead) to the PCB from the top.

montage-matrix-ctrlr-tutorial-106 montage-matrix-ctrlr-tutorial-107

Check the alignment again. Reheat and reseat if necessary.



Place and tighten the front panel with screws. Check the alignment again.

Then flip the PCB over and solder leads 1,2 and 3 of the pots.


At this point you can check that your Matrix Ctrlr is working. If you turn the pots you will send MIDI data and can navigate through the menus using the switches: the end is near my friend!

Solder the last snap-in leads of the potentiometers while checking the alignment on the front panel. Cut the snap-in leads touching the arduino power connector.


Encoder behavior is configurable in CFG Menu (see later).


Step 18 : Jacks 1/8″

J1 J2

Remove M3 screws and slowly, gently remove front panel. The LCD should stay in place.

You will now adapt jacks for the PCB by creating a ground using the cut leads from the beginning of the build.

montage-matrix-ctrlr-tutorial-111 montage-matrix-ctrlr-tutorial-112montage-matrix-ctrlr-tutorial-117

Snap the jacks into their footprint. Observe their orientation.


Using pliers and a cut lead (those from a resistor, for example), create the ground lead of the jack as in the picture below. The footprint has ground on both sides, it’s easier in the round pad.

RQ : PJ-301BM fits perfectly into the footprint, but is hard to get. Its height is not good.


Replace front panel, align and then solder the jacks while holding them to the PCB. Take your time doing this.


RQ : PZ1 is a prototyping zone next to the jacks so that you can create your own circuitry to interface the jacks to the arduino’s free pins P2 and P3 using Dupont cables.


NOTA : since PCB rev1.4 (blue), CV1 and CV2 are used to directly connect the Jacks J1 & J2 to the arduino through 8 jumpers. Use 2X4 DIL headers and configure jumpers like images below :

You will need to complete area near CV1 CV2 connectors with 2N3904 transistors, 1K & 10K resistors and 5.1V Zener Diodes ZD1 & ZD2 : this protects the arduino and limits the input voltage to +5V.


Step 19 : Lexan (critical)

Lexan v200 UV

Place the overlay on the front panel, center, adjust and use tape to hold it in place. Leave one edge free.


Peel the backing of the adhesive and cut.

montage-matrix-ctrlr-tutorial-132 montage-matrix-ctrlr-tutorial-133

Adhere one edge of the overlay to the front panel and while removing rest of the adhesive roll the overlay down across the front panel.

montage-matrix-ctrlr-tutorial-135 montage-matrix-ctrlr-tutorial-136 montage-matrix-ctrlr-tutorial-137 montage-matrix-ctrlr-tutorial-138 montage-matrix-ctrlr-tutorial-139 montage-matrix-ctrlr-tutorial-140

This is a one shot operation and a very critical step : take your time, be sober. Watch out for air bubbles while applying and you should be fine. 😉



Hint : don’t forget to remove protective plastic sheet from the LCD display. You can give a nice finishing touch on the overlay by brushing holes (softly) and sides with a used toothbrush to remove glue dust.


Step 20 : LEDs (critical)

montage-matrix-ctrlr-tutorial-127D, D, … D


Remove the front panel (yes, again).


Observe the LED orientations.

Place a LED in each footprint.














Flip the PCB back over and push each LED in its front-panel hole without forcing through the LEXAN overlay.

Use a Blue LED for ALT (convenience)


Solder only ONE lead of each LED and test they are oriented correctly.



Power up the Matrix Ctrlr. There is a boot test sequence which will flash each LED once.

Enter test mode to check each LED by pushing the unsoldered lead to the PCB with your finger. If a LED doesn’t work, you will have to remove it and re-solder it with the correct orientation ; that’s why you soldered only one lead.

Once all LEDs are OK, you can finish soldering and use your cutting pliers.



Step 21 : Final stage


Notice there are 2 screws hidden below the arduino board. Don’t forget to screw them in. Remove 8 M3 screws and replace them with 20mm spacers in the 4 corners.

Align all the potentiometer’s axes and put knobs on them and the encoder. Don’t push down too hard and check they rotate 270°.

montage-matrix-ctrlr-tutorial-152montage-matrix-ctrlr-tutorial-155 montage-matrix-ctrlr-tutorial-156

Careful: the knobs snap on and are hard to remove.

montage-matrix-ctrlr-tutorial-157 montage-matrix-ctrlr-tutorial-158 montage-matrix-ctrlr-tutorial-159


TIP : Remove a knob easily by pulling it with a strong pair of pliers with some foam for padding.


If you’ve got a back panel or an enclosure, it’s a good idea to mount it now using the 8 removed M3 screws.


Finished !




Enjoy your Matrix Ctrlr and check out the User Guide section.

A Test Mode has been implemented to test the good behavior of the interface.

You will need to set up the system in the CFG Menu.


Nota : DL1 & DL2 are two optional LEDs used to pimp the inside of your Ctrlr. They are connected to a +5V line through a 330 ohms resistor. They can be left free (useless).





Recent Posts

Summer 2020

We are sold out ! thanks for your confidence in our products 🙂

we will restock this week to ship again by the end of July. You can still place your pre-order (backorder)

During the lockdown, I have been developing : the code of the Matrix Ctrlr has been upgraded and we still need to certify some features/user interface. I will clean the Github and make something more “developer”. I’ve also started a new controller for a very underrated 80s rack that will sounds like an analogue techno groove box 😉

More details in the next days !



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