I tried to measure current at a transformer secondary that has about 1060 VAC using my Rigol DM3068. The expected current was in the microamps range (I was doing isolation testing). At the instant I applied voltage to the primary of the transformer, I saw a "matrix flowing screen" effect on the DM3068 screen. I immediately cut power to the transformer, but now the DM3068 current measurement range is shot (boty 200 mA range and 10 A range).
I did the same measurement using my UT139C (in microamps range) and it did the measurement just fine (about 4.2 uA of current). It wasn't as accurate as I wanted to be, but the point is, the UT139C didn't die.
So what could be the reason for the DM3068 to break in this scenario? I'm thinking that environmental capacitive coupling caused a high voltage to appear at the input of the DM3068, but the same type of coupling would be there for the UT130C also. So what do you guys thing could have caused this?
I know that the DM3068 current range was working before. But now both 200 mA and 10 A range don't show any current at all.