Thats what I am good at most of the time, is troubleshooting.
The rest of it, umm... not to certain. but troubleshooting is keen to me like smell is to blood hounds.
I can usually figure out where a problem lies in an electronic board within minutes. but it takes me an hour or more to pinpoint which exact components.
But then you get that weird crap when you get into CRT circuits. which throws me off quite alot. but not too bad. its easier for me to fix plasma than a CRT setup. sad but true.
on a side note, i think the hardest thing i ever had to troubleshoot that had me chasing my tail for hours, is a failed opto-isolator in power supply circuitry. thats the one thing thats drove me up the wall. but i got keen to those real quick. Second worse thing is troubleshooting an infocus projector power supply with NO schematics/service data available. some of them made me chase my tail as well, but i figured it out eventually. now i know those circuits like the back of my hand.
Then comes the power supplies that have no service/schematic data available, AND the controllers dont have public datasheets. WEEEEEEe yea... nothing to go off of for troubleshooting. I only have a 1% success rate on those. any time the FET goes, it takes the controller out in most cases and with no service info available or controller info available, troubleshooting is impossible. I can work without schematics as long as any IC circuits have datasheets/pinouts. but i CANNOT work without schematics AND no data for on-board components.
I had a philips projection unit, PTV805 i think it was. the cold side controller IC had failed, and i didnt feel like paying $30 to $50 bucks for a new one at the time. SO i built an equivalent circuit using discrete logic components, op amp/comparator, and some resistors on a small protoboard from ratshack. wired it in place, and it is still working as of this day.
at least when datasheets are available, if you have resistors burned and dont know what they are/were, at least you got something to go off of to find out what that circuit is a function of, and get a ballpark idea. I have done this ALOT. sometimes ive had to use basic ohms law to figure out what burned out crap was.