How would you diagnose this electrical problem
 

This is an under counter light fixture that has intermittently been going out or not turning on. AFA what I know about electrical problems, I know enough not to put a screwdriver in a hot outlet but that's about it. I tugged at each connection and didn't find anything obviously loose. Any help is appreciated and I think I have a tester thing. Yes, the breaker is off for the fixture.

This first picture is how it looks when all connected:

http://forums.pelicanparts.com/uploa...1173636658.jpg

And here are all the connections including the switch:

http://forums.pelicanparts.com/uploa...1173636701.jpg http://forums.pelicanparts.com/uploa...1173636714.jpg http://forums.pelicanparts.com/uploa...1173636724.jpg

Are those concrete counter tops? I really like those.

The white unit is the ballast. Basically the transformer for the light. It might be on the fritz. You did try a new bulb, right?

Yes, i was just going to add that I changed all the bulbs and yes, the island counter is concrete--incredibly good for kids--permanent marker is not permanent. Jack

I opened the 'ballast' too and checked those connections which looked fine and like nothing more than an electrical 'conduit' from the real conduit out of the wall.

here's what the inside of the white box looks like:

http://forums.pelicanparts.com/uploa...1173637703.jpg

The fixtures appear to be incandescent (halogen, Xenon, etc.). With that in mind, if the entire fixture is acting up (as opposed to just one of the lamps), then your problem isn't the lamps or the lamp sockets. Suspect items would be the switch on the fixture, the connector pins (look for signs of arcing or overheating), and wire joints.

thanks David.

All the connections look clean and fairly firm. i guess the next step is to yank out all the wires from their plastic connectors and reconnect them?

and you're right, the lights are xenon--$3/bulb. Nice.

but wait..there's more
 

is the black box the transformer? I also tugged and inspected the other connections. I also tried to check the connectivity but just don't know what I'm doing. I have one of the dumb-dumb "it lights up" when there's connectivity.

http://forums.pelicanparts.com/uploa...1173640309.jpg

so how can i tell if the transformer (the black box) is bad? just replace it and see if it works?

The black box inside is the xfmr. You are looking at a throw away unit. Any home improvement store will have something like that dirt cheap (th whole fixture). By the time you waste your time trying to figure out whats wrong and buying replacement parts you could have been done and on with life. If your testing 11v to 12v is what you should have on the load side of the xfmr and 115v to 120v on the line side. Lamp socket should be 11v to 12v also.

Black and white form the flex into the suface mounted junction box is your hot and nuetral wire. Green is your ground. Is this switched/dimmed from the unit or from a wall box somewhere in the kitchen? If its on a dimmer located on the wall then that may be your problem as those electronic xfmrs are not designed to be dimmed with a standard dimmer. Will shorten the life of the xfmr.

Hope that helps a little bit

Thanks Dan, it does help. If I can't find a transformer tomorrow I'll just buy a new unit. J