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Additional Build Notes for the Kassutronics VCO 3340

Here are some tips and suggestions for building the Kassutronics VCO 3340. This is in addition to the build instructions provided by Kassutronics.

 

Soldering the MMBF4117 JFET

The MMBF4117 should be the first component you solder to the PCB. Althought an SMD component, this component is rather easy to solder for the experienced builder. My technique is to put a small amount of solder on one of the three pads then tack the component in place using one leg, making sure the other legs are positioned property over their pads. Then solder the other two legs in place.

Note that the MMBF4117 uses two 4.7K resistors in its supporting circuit, rather than the 1K. This modification is described in the build instructions.

Preparing the Alpha potentiometers

The Alpha potentiometers need to have their anti-turn tabs removed. This can done using a sharp pair of side cutters.

Test power before inserting the ICs

Inserting the AS3340 and TL074 should be one of the last steps in the assembly. Before doing this step test the power to the IC sockets. Plug in the board to a Eurorack power supply. Pin 3 of the AS3340 should have -5V (or close to it), pin 16 should have 12 volts. Pin 4 of the TL074 should measure +12V and pin 11 -12V. 

 

The panel for the Kassutronics VCO 3340 is made of high quality birch plywood. It has a protective film on both sides of the panel, which will need to be removed before attaching it to the module.