This is a Moog Voyager Electric Blue Edition with a faulty Oscillator 1. I was offered to have a look at this synthesizer already a couple of years ago but I kindly declined since the were no schematics available. Now the situation has fortunately changed for DIY community and at the time of this writing there is a full set of schematics and service notes available.
With the schematics on hand I was able to track down the problem to the oscillator 1 main circuit with a defective CD4066 CMOS switch and LT072 Opamp.
I tested the CV signals for OSC1 from the CPU board first and they all appeared fine. There was no oscillation on OSC1 and swapping the transistor array chip from OSC2 to OSC1 dis not make any change. Therefore I suspected the CMOS switch and the Opamp which I desoldered. I added a socket for these integrated circuits since the pcb tracks are rather narrow and I did not want to take a chance by desoldering the IC’s a second time.
Once the oscillator was running again it was time to let the system warm up and perform a proper tuning of the oscillator section. This procedure is pretty standard and well documented in the now available service notes.
Obsoletetechnology 