Is this normal mosfet behavior?

Question

Electronic components

Recently I began to study the diagnostics of boards, so I was confused by this behavior of the mosfet: the program says that on the 3rd leg (highlighted in red in the image) it should be 1.05V when turned on, and the diagram says that it is on the 1.05V line, and when I measure, it shows 18.2V. Does it increase the voltage or is it a replacement?

Answer 1

+VSB is the power supply voltage. Therefore, 18.2V coming through R409.

Answer 2

U25 is highlighted in the diagram, Q29 in the picture, are you sure you are measuring the right component?

Answer 3

if it’s so jelly in the head, then it’s better to really “not study” further. board diagnostics is a search for faulty components, based on the principles of operation of this very board. but just poke at the components with a multimeter, not understanding in principle where the transistor has a shutter - usually this shines at best with nothing, at worst - with the corpses of "diagnosed" products.