Possibly you are right about R30 resistor, I didn't take it to advance about PCB mark of resistance.
On resistor is writtent 4.7kOhm.
When I returned back old resistor, I've lost all freaquency generation.
But this resistor is not R=20 Ohm, as from datasheet.
I think it's from Vo sense(+/-) circuit, because has connection with zener diod ZD1.
Now I don't have this servodrive. I will wait for profesionals judgment.