The only power I could meassure is a little 1.17v between the pluspool and the chassis, It's not constant but it looks like It's pulsing fast and indeed always on except when you put your device off, the graph bar on mine dmm could barely hold on with the speed of it.
It's related with the soft ticking sound you can hear, I've heard that the VT is constantly checking the resistance using that low voltage puls.
But It's so low I couldn't imagine it would heat up your coil


