MRG VCO (Bare PCB) Assembly Guide
This is the assembly guide for the MRG VCO bare PCB build. If you have a SMD presoldered PCB, check the MRG VCO presoldered assembly guide.
This build should be considered of medium-to-high difficulty given the number of components and steps required.
Please note that this is the assembly guide for the second version of the MRG VCO (marked as revision #7a on the PCB). The assembly guide for the previous MRG 3340 VCO is here.
Theory of operation:
- If you bought the PCB+Panel+IC only, acquire needed components (See Bill of Materials. All components used in this guide are already included in the full DIY kit.
- Build the Main PCB.
- Build the Front PCB.
- Install the front panel.
Main PCB build
The suggested order is to start soldering the front of the PCB (the one with all the resistors), and later the back, that contains the main IC, the timing capacitor, the trim pots and the eurorack 2x5 pin headers.
Main PCB Front
Step A1. Start by soldering all the horizontal resistors.
Step A2. Solder the Zener diode, being careful of orientation.
Step A3. Solder all ceramic capacitor.
Step A4. Solder the voltage regulator.
Step A5. Solder the vertical 470 Ohm resistor, the two 22uF electrolytic capacitor, and the TL072 IC. If desired, an 8-pin socket can be soldered on the PCB, instead of directly soldering the IC.
Main PCB Back
Step B1. Solder the 10-pin header.
Step B2. Solder the trim pots.
Step B3. Solder the timing capacitor and the AS3340 IC. If desired, a 16-pin socket can be soldered on the PCB, instead of directly soldering the IC.
Everything apart from the two 14-pin headers are soldered on the board now. It is time to solder the front PCB.
Step C1. Check the alignment of the PCB (label U1 is the top row), arrange the jack sockets and the potentiometers.
Step C2. Solder the components. Tip: in order to be sure to align the components to the front panel, install the front panel as in photo below and solder the components on the back.
Step C3. Solder the socket headers. Tip: In order to align the Main PCB's pin headers to the Front PCB's socket headers, assemble the two PCBs together, as in picture, and solder them in place.
All soldering is now done! The next step is installing the front panel.
Final Module Assembly
Install the front panel, using nuts and washers to keep it attached, and add the knobs to the potentiometers.
Congratulations! You have concluded a fairly complex build!
The next step is tuning the oscillator.
You can find the tuning guide here
Feedback? Suggestions? Contact me!.