Plus one on every bodies answers and zbang's especially--
Troubleshooting is really a personal thing--the way I do it is not the way you do it--for example--when I get a call that a phase is missing the first thing I do, after verifying the problem really exists, is open a panel and use a DVM to go Phase-to-Phase then phase to neutral and/or ground--and check the overloads at the same time-I have one guy who likes to start with the control voltage/circuits-sometimes I even have fun confounding the people I work with using this answer when they ask what the heck am I doing--I just answer "Doesn't feel right--it's got to be over here in this part of the circuit"-that's the intuition from 30 plus years of being a troubleshooter--remember--this is all equipment dependent
Anyway---This is a great place to learn, got some awesome people here!!! Just need to ask!!
troubleshooting is fun and you get to be the hero, unless of course you can't figure it out, then you
get to be the poophead.
the intuition part isn't something you can teach... hell, it's not something i can describe. sometimes
you will just look at something, and go hmmmm.... but intuition works a lot better when you are asking
a bunch of questions. when did it start doing it? what has been done around here recently. new operator
on the machine?
sometimes it's blind luck. once i was in a bucket at 60', tracing a stop string and other wiring on a
75' rolling high bay door where it interlocked with a top hinged crane door, to find out why the interlock
failed, and a bird came and landed on a limit switch whisker about 10' away, pushing it down....
i just looked at the guy next to me in the bucket, and said "i'm sure glad you are up here, because
without a witness, nobody is going to believe this..."
when things are deranged, i start looking at ground loops, and floating neutrals. i spent two days picking
flychit out of pepper on my work van. you'd hit a bump, and the ECC would throw different error codes
each time. the engine remote start would activate. the alarm would go on, and off by itself. crazy
unrelated system failures.
the problem? a loose connection on a binding post for the primary +12 volts to the under hood
fuse block.