OK, on the back metal plate of the plasma display panel there is a sticker marked SAMSUNG with VS, VA and other voltages written on it. This is the "panel sticker". Please note the voltages or take a picture of the sticker for me to see. Typical range for Vs and Va on 2012 series Samsung is 205 to 215V and 50V to 58V respectively.
Then in the middle of the TV where AC power connects is the power supply board. There should be test points for Vs and Va on there, among others. Set your DMM on volts DC; if it has separate ranges, select 600V or 1000V. The black probe goes on an exposed part of the chassis and the red probe on the test point. Check the voltage matches the panel sticker within about 2 volts.