this is an advanced, involved, and difficult build
trouble shooting tips and common problems(please read these before trying to contact me)
- “my led is always on”: check both pcbs for solid joints and ensure there are no short circuits or joints overlapping onto traces. make sure the led orientation is correct(flat side facing down)reflow the led legs and all the 3904 transistors, and maybe the L2 resistor. try replacing the led in question.
- “my channel is working but not coming out of the sum, or my channel is not working”: check both pcbs for solid solder joints and ensure there are no short circuits or joints overlapping onto traces. reflow the all the jacks and pot related to the channel in question. check and reflow all the solder joints of the jumpers connecting the two pcbs.
also worth mentioning, the area of the trimmers on the mother board is very sensitive as the trims are normalled to positive and negative voltage. debris can get stuck and cause short circuits very easily. so make sure nothing falls in there or get stuck in that region.
also be very careful trimming legs on the mother board after soldering. the traces are very small and prone to being cut if you are not careful.
get in touch if you need the eagle files(schematic/pcb files)
build docs for v5.3
thanks to mr gleeson for updating the docs
BOM for VnIcursal version 5.3/5.4
the trimming process requires 2 calibration procedures:
- there are 6 trimmers on the pcb, corresponding to the 6 channels, for zeroing out the bleed on each vca. you can get all scientific and measure the db, but i just do it by ear. insert a harmonically rich waveform like a saw or square into the audio input with the panel control/potentiometer at full ccw(counter clockwise)and plug the vca out to whatever mixer/amp chain you work with(maybe turn your mixer/speakers up louder than usual) and then turn the trimmer on the pcb slightly to the left/ccw until the vca is silent. If your vca is silent from the start then good, and move on and repeat for each channel.
- next is calibration for the cv overlap/bleed. use the same harmonically rich waveform from step one and insert it into an input. plug the vca out to same mixer/amp chain. now insert a dummy cable(meaning plug one end of a cable into the vca and leave the other end disconnected) into the cv input. turn the panel control/pot fully clockwise(open) and listen if there is any bleed from the audio in. if so, turn the trimmer on the pcb slightly to the left/ccw until the vca is silent. repeat for each channel.