[morzh]

To be honest, having spent most my life in electronics and a sizable part of it in troubleshooting it, I no longer think of components as something....it is some mixed-up common picture in which when there are certain symptoms I have some intuitive image of something that I cannot explain that just tells me "look there".

Same was happening when I had to debug embedded C-code (that was long time ago) - I looked through the code (someone else wrote it), looked at what was happening and then I just looked in a certain procedure.

I don't know how to explain it - but it is associative, I would not be able to tell how it happens. Of course when I find the problem I probably can explain why it was happening, but not the way I found it.

I guess at some point having enough experience in something one starts thinking on a system level.

And the interesting thing is, when this level comes, one no longer has to even know how every single component functions exactly. For example, I do not have much experience with tubes and the schematic solutions using tubes, my lifelong experience is transistors and then microchips, analog or digital. At some point though (except for the part where you get zapped) they are the same.

So, for example, in this particular case I did not think of switch as a resistor, capacitor, bad switch etc.
I just looked at the common picture and some invisible finger in my brain (no, not the middle finger) pointed to the switch. That was it.

Or in Puh-Pow's case, the tube I pointed to first (and the idea this or the next one) is bad despite having been tested.....there was a picture and it did not fall in a certain pattern, so this tube was sort of standing apart, and so I pointed at it first and to the next one as the second possibility. Again, I did not analyze much - it was intuitive.

And, no, it is not a 100% - sometimes you have to analyze on component level.