I come across many circuit boards at my job and I while I have to understand exactly what the board should be giving as inputs and outputs I don't have to understand what's the board is doing within it. For instance, I know that a board should have a high voltage switch close when another area of the board has a control voltage applied so if it doesn't do that I simply replace the board. But I never really understand why it's not working, mainly because that's just not my job. Also we aren't allowed, by manufacture's orders, to repair the board but only replace it. With that said, over the last couple weeks I've brought home several boards to try to analyze them but it's not going well. I have a multimeter and some transformers to apply certain voltages but I'm at a loss when it comes to getting into the "brain" of the board like timers, transistors and the programming of it. What tools can help me dig deeper into a circuit board? Thanks.