Hi Bob,
Firstly thank you for sharing all this insightful information about the Polysix!
After several unsuccessful attempts to tune the voices of my Polysix using following the service manual, I stumbled across you directions on how to adjust the anti log circuit, I was hopeful it was the answer to why I was having so much difficulty tuning my P6 but have been unable to complete the procedure.
When measuring the voltage at R147 and adjusting VR2, I'm getting a bottom reading of 3.2656 (completely counter clockwise) and a top reading of 3.3318 (completely clockwise). Therefore I adjusted to a centre point of 3.2987 V
I'm am stuck because I cannot adjust VR3 to reach my lowest value (0.4123), it is out of the range of the trimmer. It maxes out at about 0.25. I tried adjusting VR2 to completely counter clockwise but still that value divided by 8 is out of range for VR3. I hope that makes sense.
Any advice on how to further troubleshoot this would be greatly appreciated.
One last bit of information I tested pin 7 of IC18 and it gave a reading of -3.2 which I believe is normal.
Cheers,
Jay