I have an over-the-stove microwave/ hood vent combo with 2 adjustable-brightness lights. The lights appear to be 12V lamps with a G4-style connector, and they burn out all the time... like every 4 or 5 months. The bulbs themselves are like $8 a piece, and you have to take apart the hood with a special tool to get at them so this was getting to be a frustrating experience. I decided to go with LED to reduce the maintenance.
I found some 12V LED lights with the G4 style base, and bought them. When they arrived, I replaced my burnt-out bulbs with these LEDs.
They didn't work. There looked like just a little bit of light were coming out of them, but nothing near my expectations. I tried reversing the polarity with no difference in result.
I figured that the power to the light sockets must be AC, or the LED's did not support different levels of voltages (I got them cheap from China). So, credit card in hand, I went looking for LEDs that could handle AC and were dimmable. I found some, ordered them, and received them.
I tested it out after I replaced the first bulb. Eureka! The bulb was bright, and dimmed properly. All done. So I replaced the second bulb.
All of a sudden, both bulbs no longer work: very dim, not dimming, just like my first LED experience. Scratching my head, I experimented:
1 LED installed, 1 incandescent: bright, dimmable light
2 LED lights installed: dim, barely visible
1 LED installed, other socket empty: dim, barely visible
2 incandescents installed: bright, dimmable
I'm trying to figure out how the sockets could be wired that would give me this result, and what I can do about it.