PZT monitor is not lying to us, I've measured it with a voltmeter. But PMC SERVO is still interesting. If I break the loop after PMCERR signal monitor (C1:PSL-PMC_BLANK=0), I can change PZT voltage from 0V (C1:PSL-PMC_RAMP = -7.3) to 132V (C1:PSL-PMC_RAMP=-10.0). If I break the loop by enabling TEST1, PZT voltage goes up to 294 V, though voltage on the TEST1 and MIXER MON is 0.