Yusynth (Part 25)

I finished two more Yusynth VCO modules. I got the front panels from Schaeffer again, but this time I corrected the mistakes I did on the first one. So everything fitted a bit better now. I used the first VCO I build a while a go as an example. That saves a lot of time. I used the same colors on the wires and the same routes as well. I think I build these two in about the same time that I build the first one alone. I also installed a MOTM style power connector on some nicely twisted leads as you can see. I did this for the existing VCO as well and decided I'm going to do all Yusynth modules this way.

After that I hooked them up to the lab power supply to do some initial tests. All looked well. Then I started with the calibration process. I didn't tune them yet, but I did the wave shape adjusting. On the oscilloscope you can see the output from the Sine Wave jack. This was as good as I could get it. I wondered a bit about the triangle wave. Those were not quite the same on the two newly build modules. But I will have another go at them when I am going to tune them. It was not that drastic by the way, but just some minor difference. Could be component tolerances I think.

I made one stupid mistake by the way. When I finished the first one of these two I put some cooling pasta on top of the tempco that is on the PCB and then I decided to put the cooling paste on the other one as well before I had wired it. Well never do that ;) You will hit the stuff with your wires or your hands and it is sticky. Another lesson learned today. Here you see a nice picture of the three Yusynth VCO next to each other. I still have one PCB left so maybe I will finish that one as well. I will have to order a front panel for that one then though. I'll let you know when I do.