Chord VCO 102 Build Guide

Assembly Instructions

The Chord VCO 102 module has particular build requirements but we do recommend also reading the ‘General Build Info' page.

The Chord VCO module differs from most other modules in that it has two PCBs double stacked. Assembly of each individual PCB is straightforward and covered in the General Guidance’ booklet. Minor differences are:

1. Four x 5-way + 1 x 2-way female headers are soldered to the components side of the pot PCB and to the underside of the VCO PCB.

3. Soldering the headers and keeping them upright can be tricky. We find ‘dry’ assembling the two PCBs together and to the back panel first. Then solder the headers on the VCO PCB, remove from the back plate and solder the headers on the Pot PCB.

4. The chord switch header should be soldered to the Pot PCB first, fix the Pot PCB to the back panel and mount the 16-way chord switch. Place the breakout PCB 7215-900 over the switch and header pins and solder in place.

Calibration

1. Before fitting the piggyback VCO PCB, power up module and allow to ‘warm up’ for 5 minutes
2. Using Pr2, adjust the voltage at TP1 to 4.266V
3. Power down and fit the VCO piggyback PCB

4. Set the coarse and fine controls to 0%, quantize off, VCO’s x3/4, pulse waveform and PWM initial width to 50%.

5. Apply a 5V CV to the V/Oct input

6. Using Pr1, adjust the voltage at pin 3 (middle pin near R121) of J6 to 2.8V

7. Apply a CV of 6V, set chord to CM7 then using P1, adjust the VCO 1 output frequency to 2093Hz. Repeat for P2/VCO 2 but 2637Hz, P3/VCO3 but 3136Hz and finally P4/VCO4 for 3951Hz.

8. Carry out an auto tune.

Oscillator PCB Parts List

 Pot PCB Parts List

Module Parts List

Oscillator PCB Layout 

Pot PCB Layout 

 Rotary Switch BOB