Introduction
We find that wiring a MFOS PCB to the front panel controls is both time consuming and often detracts from the overall finish. We are not able to alter the MFOS PCBs to make panel wiring easier so we approached the problem from a different angle. We chose to mount the front panel controls on a mini PCBs (breakout boards) that take the panel controls to a JST type XH socket into which is plugged a lead. This lead is then dressed to the main MFOS PCB (or sometimes to other panel controls) and soldered into the respective pads. Many breakout boards have solderable jumpers for making common connections as well as thin tracks to cut where panel mounted resistors need to be connected inline with say a pot wiper. MFOS projects may require multiple breakout boards so we bundle these altogether and offer them in one ST Synth Panel Breakout PCB Set. The pack description will further describe the wiring colour code and what if any links need to be made or cut.
This method does have other advantages other than just time saving and appearance:
- Time saving
- Neater more professional appearance - improves resale value
- Takes care of common connections between panel components
- Has space to accommodate panel mounted resistors and capacitors
- Can improve reliability - have you tried soldering a diode, LED and a wire to one pin on a toggle switch on the 16-step sequencer?
- Makes fault finding easier
If you have any reservations about using connectors, then simply solder wires direct to the breakout boards. Takes longer but you still get all of the other advantages.
The boards are designed to fit our front panel component spacing so you will see references to pitch and whether it is in the 'x' or 'y' or both direction. At the time of writing, there was 30+ breakout boards developed for pots (using pot brackets), sockets (jack and banana), switches and LEDs. Whilst these will not take care of every panel component on over 40 MFOS projects, it will go a long way to achieving it. As we work through making up each MFOS project with these breakout boards, we will see where improvements can be made or even create more breakout boards to provide the best possible solution.
Specific Information on the 2x1y Sequencer Rotary Switch Panel PCB (33x). Board size: 71 x 38mm
7210-761 PCB accommodates two 1 pole 12 way rotary (wafer) switches. The required switch connections are brought out to a 12-way JST connector (see 7210-112). S12 can also be wired direct to this board and a further 5-way JST connector (see 7210-105) is provided for this. C11 and D13 are mounted on this PCB instead of direct to the switch contacts.
Assembly
Solder C11 and D13
Solder in the JST socket noting that the slots in the 12-way socket housing point towards inwards towards S2. The slots for the 5-way point towards the top of the PCB
Place the PCB over the solder connections on rear of the switches.
After ensuring the PCB is sat properly and level, you can commence soldering the terminals.
Wiring Colour Code
Pin 1 (black wire) is at the bottom of the board
| Colour | Function |
| Black | S2 Pin 1 |
| Red | S2 Pin 2 |
| White | S2 Pin 3 |
| Yellow | S2 Pin 4 |
| Orange | S2 Pin 5 |
| Green | S2 Pin 6 |
| Blue | S2 Pin 7 |
| Violet | S2 Pin 8 |
| Grey | S2 Pin 9 |
| Brown | S2 Pin 10 |
| Black | S2 Pin 11 |
| Red | S2 Pin 12 |
Pin 1 (black wire) is on the left
| Colour | Function |
| Black | S1 Pin 4 |
| Red | S2 Pin 3 |
| White | S2 Pin 2 |
| Yellow | Rnd on S12 (n.o 1) |
| Orange | Gnd on S12 (Com 1) |
It is always worth checking the wire colour sequence to ensure it matches the above just in case there has been a mistake at the factory in the assembly of the cable.
Typical examples of projects that use this board: 16-step quantized sequencer