Also - see these Build Videos:
Part 1 - LEDs
Part 2 - Teensy (Not yet updated for Teensy 4.0)
Part 3- Pots and Testing
Part 4 - Switches and Assembly
The key-switches are going to be the VERY LAST thing you solder. After you solder the switches in, everything on the inside is going to be inaccessible.
Ideally you want to be able to test all the LEDs, the OLED, and the pots/encoder before putting the switches on.
I'd also suggest testing each switch connection with a piece of wire or tweezers so you can confirm the diodes/LEDs/caps are all soldered correctly.
Follow the order of operations here to make your life easier. NOTE - the keyswitches are absolutely the last thing you solder. Make sure everything else looks good before you do the switches.
Also important - Keyswitches are snapped into the keyplate first (before soldering them).
Don't forget to put the spacer layer in-between the main PCB and the keyplate before you solder all the switches.
I work with a fine point tip on my iron at 400C. With this setup I typically hold the iron on a pad for about 2 seconds and then apply a bit of solder and then hold the iron there for anything 2-3 seconds. You want to watch for the solder to flow around the joint, but not to hold the iron there forever.
See Adafruit's guide to excellent soldering for lots of good tips and tricks.
Nice to have tools:
- flush diagonal cutters
- tweezers
The LEDs are Reverse Mount and are soldered to the back-side of the PCB with the LED facing towards the top of the PCB. When looking at the back of the PCB as in the picture, the GND leg is the top right pad for each one (marked with a red triangle in the picture below). The LED itself has a "notched" leg for GND.
Set each LED into position (tweezers are handy for this) and then double check the ground pin is in the right position.
Solder/tack the bottom right corner pad of each LED to hold each one in place. Then check the orientation of each LED to be sure they're nice and square in the hole. If not, warm up the solder there and reposition as needed.
After you're happy with the LEDs being in the proper positions - solder the rest of the pads.
For the keyplate to fit properly, the Teensy MUST be flush-mounted to the top of the main PCB.
(Teensy 3.2 and PCB v1.5 only) An insulating kapton spacer is included with your kit . Use this between the bottom of the teensy and the main PCB to reduce the chances of unintended shorts.
See below for Teensy 4.0 instructions (2023 v2.0 boards).
Teensy 3.2 jig
Use the included acrylic jig to set up your Teensy like the following for soldering.
Short side of the headers goes down to the jig and the long side up.
Add a 1x3 and 1x1 in the appropriate places. The 1x1 directly next to the 1x3 is not connected to anything so you can solder that or not (your choice).
Add the two spacers (maybe even tape those two together so they don't wiggle around.
Drop the Teensy into place. There should just be a small amount of header sticking up from the Teensy at this point.
DON'T SOLDER A HEADER TO THE VUSB PIN - it's not used. This is the 1x1 pin/hole right next to the USB jack on the Teensy (on the inside row).
Teensy 4.0 jig
The Teensy 4.0 version (board v2.0) only uses the 2 outer rows of pins. (4 less pins to solder!)
Note the plastic parts of the jig have an etched out area - this is to allow space for the components on the underside of the Teensy 4.0.
Soldering
Solder the pins to the Teensy first.
Then remove the jig and carefully remove the black plastic from the headers. Hold onto the black spacers for the next step.
After you've removed the plastic, slide the thin yellow kapton spacer thingy onto the bottom of the teensy - this should end up between the teensy and the main board as an insulator. Then drop the Teensy onto the main board so it sits nice and flat.
To keep the pins from wiggling around while soldering the bottom, either
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Put a big piece of tape over the whole teensy to keep it in place and to keep the pins from getting pushed out
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Or push the black plastic bits from the headers onto the pins to hold them in place while soldering
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Or both
Flip the board over and solder the pins to the bottom. Try to tack/solder one pin on either side in place while pushing your finger against the teensy to make sure it's absolutely flat against the main pcb.
Once you're happy with the flatness - solder the rest of the pins. Be careful not to push down on the pins while soldering.
Using flush cutters, trim the pins away. Be careful not to nick/scratch the pcb.
The OLED display sits on a regular header (not flush like the Teensy) the display should be close to level with the keyplate (the OLED glass will be about 0.5-1mm higher than the keyplate).
TIP: I suggest using a section of the header plastic you removed from the Teensy headers as a spacer to hold up the other side of the OLED PCB. Glue or tape a 1x4 chunk of the header plastic to the back of the OLED pcb and this will keep it level and support it while you solder (and after).
Trim the headers on the top side of the OLED if you're worried about something shorting there.
Snap pots and encoders into place and solder.
You may need to gently squeeze the snap-in mounting pins together a tiny bit to get the pots to snap into place.
At this point you can flash the firmware and do some testing.
See the instructions here (loading a HEX file) - https://llllllll.co/t/how-to-flash-the-firmware-on-a-teensy-micro-controller/20317 if you don't know how to flash firmware to a Teensy.
The OLED should display something as soon as you plug into USB power.
On startup all the LEDs should show a rainbow pattern.
If your LEDs work up to a certain point (e.g. LEDs 1-7 work, LED 8-27 don't):
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The problem is most likely a bad soldering joint on the erroneous LED itself, or on the LED that is RIGHT BEFORE this LED in the chain (in the above example, check LED 7 and 8). Carefully re-solder all connections again to fix the problem (melt the existing solder again, maybe apply some more, make sure it flows nicely between LED and PCB pad)
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Check that the orientation of the LED is correct (see pictures above)
You will want to test the pads for each keyswitch on the PCB using tweezers or a piece of wire (a piece of wire will work much better than tweezers!). This is also a second check that the LED for that switch is working correctly.
When you test the AUX key (top left-most key) - this will light up a total of 15 LEDs on the board. This is normal.
If the LEDs do not light up for each switch contact, check the LEDs again first. A good test is to remove power and re-plug to see if the rainbow LED pattern shows on startup. If all the LEDs are working OK examine the diode adjacent to that switch position and be sure the soldering looks OK.
Note - There are groups of Rows and Columns for sets of switches. If you get a group lighting up, it may be a corresponding pin on the Teensy for that row or column. Ask on Discord if you're stuck here.
Use the browser_test script to show USB-MIDI input to your computer. Then you can check to be sure the pots are sending CCs and that you get MIDI note-ons/note-offs when you test each keyswitch's pads. Be sure you have the oct (octave) set to 4 on the display (change with encoder knob).
Also test the Hardware MIDI 1/8" jack with an appropriate adapter and synth. Check the A/B switch position for your particular setup (try both to be sure you have the right one).
Carefully remove the paper backing from the acrylic parts - the spacer and the back plate. Then set these aside for the next step.
The spacer layer is pretty fragile - try not to break it. However, even if it does break, it might be fine since this sits in-between the other layers.
Check the orientation of the switches. The pins go towards the bottom-half and the LED window at the top.
Snap all the key-switches into the keyplate (from the top).
The switches may be a tight fit. Be sure they are snapped all the way into place.
Set the black acrylic spacer layer on the main PCB and align it around the various components. Then set the keyplate with switches into place to be sure all the pins line up and everything is nice and flat. You may need to gently bend key-switch pins into place if they got slightly bent in transport.
Use the included case screws/nuts to fix everything together for soldering. I suggest using the holes down the middle of the case. This will ensure the key switches are held in place for soldering and that everything will remain flat.
Solder all the switches.
Then remove the screws/nuts and then reassemble with the bottom plate.
The nuts fit into the captive cutouts on the bottom plate.
Add the teensy cover plate with the two remaining screws/nuts.
Push the knobs onto the pots, make sure the marking on the knob aligns with the marking on the pot.
Then install the keycaps with the window on the top for the LEDs.
