Hi everyone, with the help of the service manual I found the variable resistor and resistor responsible for speed adjustment. I replaced the fixed 22k resistor (R741) and replaced it with a variable one. Works great BUT : Under a specific setting the motor's speed starts to oscillate and the more I slow the more the speed get unstable resulting in extreme flutter. I tried to find where it was coming from with a scope and it seems that everything is working correctly it's just that the circuit is not tuned for low speed. I'm not understanding the role of every parts of the regulation circuit so I don't know what to do to tune it properly. I tried naively increasing the capacitances around the "servo control", "sample and hold" and "lowpass filter", the system seems to change but still oscillating. Doed anyone would have a clue on how to properly tune the system ? If that's possible at all ? Sorry if you think I should not try to hack such a fine piece of equipement, I'm being very careful haha. Cheers, David
