MST VCO problem

stringsthings · Joined: Feb 07, 2015 Posts: 11 Location: US

Has anyone built the MST VCO? I can't get mine to work right. I do get signal out of each output but the frequency range is very low. When I turn the coarse knob, I can only raise the frequency about 50hz. So I have no range of frequencies.

I did e-mail synthrotek, but they didn't have much info.

If anyone has built this, I would appreciate any voltage information. I have checked voltages on each IC and they are getting the proper power voltages. And the range of voltages on the coarse and fine pots seems to be alright. There's just little to no effect on the output frequency.

edit:
- Another round of trouble-shooting solved the problem. I removed the IC's and then checked the voltages on each socket. All of the voltages seemed to be alright. Turning the main board over, I re-inspected the solder joints. I noticed two joints that were very close together and there was a possible short with the ends of the component leads. The multimeter revealed that the joints were shorted. Clipping the lead ends shorter solved the short. I put the IC's back in and tested the circuit. Everything was working properly. I now have a full range of frequencies from each output.

If feels very good to solve this one. I had gone thru 3 or 4 long debugging sessions with limited success. So I put the circuit aside for a couple of weeks before trying again. The time away proved to be valuable.