Electrical question - i feel like a moron here

alright, let me first degree in college electrical engineering. why feel dumb asking basic question... though feel retard, i'd rather swallow pride , ask basic question fumble on forever!

okay in our yard, have lighting system hooked timer. lights come on @ night - go off @ day. pretty standard. i've noticed third of lights have gone out. went transformer box timer electrical system is. see there's 1 120vac line comes box. there's 3 12v dc lines go out (a +/- terminal each line, total of 6 wires).

since third of our lights off, i'm figuring 1 of 3 terminals isn't supplying voltage anymore. went radioshack grab multimeter. wanted check voltage on each of dc lines.

racked brain college... , remembered if want measure current, need break circuit , reconnect it. , if want measure voltage, should able touch 2 leads of multimeter +/- terminal. set multimeter vdc setting , touch leads +/- terminal. i'm expecting near 12v. nothing. 0. no volts. okay weird. try next one. same thing. try next one. same thing. freaking lights on right know there can't 0 volts on line.

basically, have feeling i'm forgetting basic, or missing something... can young undergrad took basic ece me out? appreciate it! want these damn lights workin! in order fix anything, need diagnose problem first!

 

do basic process of elimination. confirm transformer putting out full 12volts. if is, eliminates 1 point.

output wires lead light, 1 pair in series. go fires light, remove bulb, , check voltage there. **note** make sure multi meter set dc if output of transformer. if a/c, set that.

should reading @ first working light. go next in line , check it. hood, 1 wire has broken or become disconnected in series.

experience, 25 years in apartment maintenance, lots of electrical trouble shooting.

 

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