Yes, be careful inside monitors, especially if
you're not confident of what
you're touching. The tube can have several to tens of kilovolts on it.
Ethan's suggestion of probing around with a wooden or plastic chopstick is
a very good one.
It is _very_ difficult to come into contact with the EHT (fianl anode
voltage) accidnetally unless the insulation is breakign down. It's pretty
much confined to the flyback transformer, possibly an external rectifier
diode, and the CRT anode connecotr. OK, some colour monitors have a high
vlaue sense resisotr/potional divider hung off this supply too, but it's
all encapsulated and insulated so you won't accidentally touch it.
But you will find high voltages ont he CRT base pins and thus the monitor
PCB tracks. Expect a 80-110V supply for the video output stage (CRT
cathode), and up to 800V on the earlier anodes in the electron gun.
Although they are not likely to be able to supply enough current to be
fatal, they are certainly painful!
It's not uncommon to find a few hundred voltas on the brighness control
wires, so be careful there.
(Most monitors have a brightness control that varies the control grid
voltage and this can be a hundred volts or so _negative_ wrt ground.
However at least oen monitor (the one used in the HP120 and HP150?) has a
brightness cotnrol that varies the first anode votlage, and has 400V
positive on it. No I didn't find that the hard way!)
-tony