I used my Tek P5200 high voltage differential probe to test SMPS. I had found big offset voltage -9mV at 1/50 mode. If I changed to 1/500 mode, the offset voltage was less than -1mV. I tried to adjust R26 to minimize the offset voltage. Unfortunately, I couldn't adjust to 0 mV at 1/50 mode. The adjustment range of offset voltage was from -2mV to -15mV. When I had adjusted the offset voltage to -2mV at 1/50 mode, I measured offset voltage +6mV at 1/500 mode. Anybody have the calibration procedures of Tek P5200 HV probe? Or how to minimize offset voltage of both modes?