MFOS VCF 24dB 5U Synth Panel Breakout PCB Set

(£8.15 UK, incl VAT)
200 g
In stock

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 (not included with set but available separately). 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.

The panel PCBs can also be used with our YuSynth range. YuSynth PCBs are better laid out as regards panel wiring but can still take advantage of these breakout PCBs.

This pack contains the following breakout PCBs:

  • 7210-703 x 1
  • 7210-704 x 1
  • 7210-733 x 1

Whilst you can solder wires between the breakout PCBs and the main PCB, we do recommend using our JST cable assemblies. For the VCF, you will need the following:

  • 7210-109 x 1
  • 7210-110 x 1
  • 7210-112 x 1

See the Build Guide tab for wiring information on how to use these breakout PCBs with this module.

Guidelines when building a VCF module using our panel PCBs, front and back panels, PCB holder and the MFOS main PCB.

Parts needed

  • Assembled MFOS PCB #7210-004
  • Front Panel #7210-504
  • Back Panel #7210-804
  • PCB Holder #7210-904
  • 3-Way Pot PCB #7210-703
  • 4-Way Pot PCB #7210-704
  • 9-Way 1/4" Jack Socket PCB #7210-733
  • 12-Way Cable Assemble #7210-112
  • 9-Way Cable Assembly #7210-109
  • 10-Way Cable Assembly #7210-110
  • PCB Holder Brackets Fixing Kit #7210-181
  • PCB Mounting Fixing Kit #7210-182
  • Additionally you will need our Switchcraft Jack Sockets #7212-208 (Pack of 8)

Panel PCB Preparation

PCB #7210-703 requires links A, B & G solder bridging.

PCB #7210-704 requires link A bridging

PCB #7210-733 requires link J5 bridging


Pot PCB Assembly

There are two pot PCBs to assemble, the 3-way PCB for the mixer controls has all three pots soldered in. The 4-way pot PCB has only 3 of the possible 4 pots soldered in. See the photos below to help identify the pots.

Make sure the solder bridges are done before assembly as it can be difficult to solder certain ones afterwards.

  1. Solder in JST headers noting that the slots in the socket housing orientation.
  2. Remove any anti-rotation lugs on the pots
  3. Insert pot into bracket and temporarily do up lock nut
  4. Insert pot with bracket into PCB and solder in position ensuring the pot bracket sits flat on PCB. Only solder the bracket lugs on the bottom of the board
  5. Repeat for remaining pots
  6. Remove pot nut

The socket PCB is described below.

Socket PCB Assembly

General advice an assembling socket boards can be found on the PCB product page. Solder bridge J5 is required as it allows for a ground connection. Ensure the JST socket is also soldered in before the sockets. Solder all sockets in except for the centre one J5. See photo above

Panel PCBs Completed

You now have 3 panel PCBs populated and ready for assembly to the panel (front and back panels)


Assembly order is PCB mounting angle brackets, socket PCB, pot PCBs & finally the main MFOS PCB itself. Note the orientation and posutions from the photo below.


Panel Wiring

With the assembly of the Panel complete, it's time for the wiring.

Firstly, plug in the JST cable assemblies, they will only go in one way around as they are keyed.

Not all of the wires are required so we suggest cutting them off at the plug.

Cables not required are:

3-pot PCB

  • Whitw
  • Yellow
  • Green
  • Blue
  • Grey

4-pot PCB

  • Grey
  • Violet
  • Blue
  • White
  • Black on terminal 1, not the black on terminal 11

Socket PCB

  • All required, do not cut off any.

Inter-Panel Wiring

3 wires on the socket board are wired to the 3-pot PCB and 2 wires go to the 4-pot PCB, we suggest soldering these first. See the table below.

Socket PCB Cable

J10 Brown Gnd 0V
J9 Grey R3 position on 3-pot PCB
J9 Violet XRES
J7 Blue CV1
J6 Green R6 position on 3-pot PCB
J5 Orange Ground connection on 4-pot PCB
J4 Yellow CV2
J3 White R9 position on 3-pot PCB
J1 Black R3 position on 4-pot PCB

Now the remaining wires can be dressed and soldered to the main PCB. We tend to route the wire first to get a final length before cutting. The cut end is then stripped and tinned and placed into the respective pin on the MFOS PCB. With a fine tipped soldering iron (<1mm), we then solder the wire in position from the top of the PCB. We each have our own preferred method but this works well for us.

Wiring Schedule

3-Way 3 Pot PCB

1 Black Gnd
2 Red AIN 1
3 White Cut Off
4 Yellow Cut Off
5 Orange AIN 2
6 Green Cut Off
7 Blue Cut Off
8 Violet AIN 3
9 Grey Cut Off

4-way Pot PCB

12 Red RES3
11 Black RES2
10 Brown RES1
9 Grey Cut Off
8 Violet Cut Off
7 Blue Cut Off
6 Green CO3
5 Orange CO2
4 Yellow CO1
3 White Cut Off
2 Red CV3
1 Black Cut Off

Once each wire is routed and soldered, it will be ready for dressing

We use 100mm cable ties to dress the cables. Module is now complete and ready for test and calibration.


Wiring is now complete except for the +/-12V supply whcih depends on your own system. We solder in a 3-core cable with a plug on the end (see photo above) which we use for power distribution in our racks. Next is a visual inspection and we also apply power before inserting chips to check for correct polarity across one of the IC sockets.

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