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:
- 7210-704 x 1
- 7210-712 x 1
- 7210-762 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 Delayed Modulation, you will need the following:
- 7210-103 x 1
- 7210-109 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 Delayed Modulation module using our panel PCBs, front and back panels, PCB holder and the MFOS main PCB.
- Assembled MFOS PCB #7210-025
- Front Panel #7210-525
- Back Panel #7210-825
- PCB Holder #7210-925
- 4-Way Pot PCB #7210-704
- 2-way Socket PCB #7210-712
- Delayed Modulation Switch + LED PCB #7210-762
- Pot Brackets #7300-000 (4 reqd)
- 3-way Cable Assemble #7210-103
- 9-Way Cable Assembly #7210-109
- 12-Way cable Assembly #7210-112
- PCB Holder Brackets Fixing Kit #7210-181
- PCB Mounting Fixing Kit #7210-182
- Additionally you will need our Switchcraft Jack Sockets #7212-202 (Pack of 2)
Fit the switches, sockets and PCB brackets (do not tighten the brackets up the screws into the aluminium panel just yet) noting their orientation as below.
Panel PCB Preparation
Solder in wire links between R2 & R3, R5 & R6 as below. Also solder bridges B & C.
Next, solder in the 12-way JST socket noting that the slots face towards the top of the PCB.
Pot PCB Assembly (see photo above)
- Remove any anti-rotation lugs on the pots
- Insert pot into bracket and temporarily do up lock nut
- 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
- Repeat for remaining pots
- Remove pot nut
Solder the 3-way JST socket to the jack socket PCB and the 9-way JST socket to the toggle PCB, see photo below for correct orentation of the JST sockets.
Place the toggle PCB over switches and LED, ensure it is level and then solder all of the connections. Note that the long lead on the LED goes to the + pad on the PCB. Place the jack socket pcb over the socket pins and solder in place.
Fix the main PCB to the PCB holder and fix to the PCB brackets. Then insert the assembled 4-way pot pcb and fix in place using the pot nuts. Finally, tighten up the angle brackets.
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:
4-way pot PCB
All wires go to the main MFOS PCB as described in the wiring schedule tables below.
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.
This particular PCB from MFOS is lacking any 0V (ground) pads for the front panel connections. So we soldered the brown wire on the pot PCB to one end of R41, see photo above. Not ideal but works.
Pot PCB Cable
|10||Brown||Ground (R41 on MFOS PCB)|
|3||Red||Ground pad on pot PCB|
|1||Black||ground pad on pot PCB|
Wiring is now complete except for the +/-12V supply which depends on your own system. We solder in a 3-core cable with a plug on the end 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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