Put up two sets of these a couple of years ago. One set is now behaving
oddly. They're both operated from the same switch, but I'm not exactly
sure how they're wired together, I didn't do that bit.

They're 12v systems with a transformer integral to the mounting point on
the ceiling for the track - so not recessed at all. 4x35w halogen
lights on the track, one transformer per track.

A couple of weeks ago, one set didn't come on. From past experience I
know if a single halogen blows, the others remain lit, but started
replacing them one by one anyway. First one I swapped, it all lit up
when I tried it again, so I swapped the 'old' bulb back in, still
worked, so I figured maybe it had worked loose from the heat or something.

Then a few days back I noticed in the periphery of my vision that the
lights (again, just this one set) seemed to be intermittently going
brighter. I've seen this sometimes when the supply's been a bit ropey,
but nothing else was affected. It cleared up, and I thought no more of it.

Tonight, having had the lights on a couple of times today, I discover
the entire set is out again. Having changed the bulbs one by one it's
still not working, and I'm none the wiser.

Having left it off and tried again, it's still dead. I'm not taking the
cover off till I can see what I'm doing tomorrow when the sun makes an
appearance again, but would appreciate some ideas on what I can look for
and try.

I have a multimeter and have a vague idea on how to use it, though most
of my experience has been on much lower voltage stuff, not mains, which
is another reason why I'm leaving it till tomorrow, so I can see exactly
what I'm about to electrocute myself with :-)

Anyone else had this, I'm assuming it must be something to do with the
transformer, but a bit puzzled why changing the bulb last time seemed to
kick it back into life. I've checked all the track is secure and tight etc.

TIA,

Velvet