I want to learn the JFET, BJT adn IC voltages

[JackSkellington]

Hello.
Sometime, especially when I have to debug a circuit, I need to know the voltages of some parts as transistor or IC. But when I got the measurements, how I know if them are correct?
Is there a sort of guide, table or instruction?

Thanks for helping!

[Scruffie]

I did make this post before, it doesn't cover a huge amount but it's better than nout http://www.madbeanpedals.com/forum/index.php?topic=19934.msg193641#msg193641

Really though, to know the answer you either have the voltages of a working unit to compare to, or to have the schematic and understand what is happening in the circuit.