What's wrong with this LED light?

[TechTree]

Hello,
Just out of curiosity I disassembled an LED GU10 light to see what's inside and found, a rectifier, a few capacities, and a small transformer. It was working fine before, but when I took the plate that has all the LEDs soldered to it and tired to power it on my DC variable power supply it didn't work at all. But would dimly glow if I touched the plate, hardly letting of any light.

The original LED driver circuit outputs only 0.70V, so I connected it up to my power supply set to 0.70V and got nothing, unless I touched the plate then I got a dim glow. I gradually increased the voltage to 5V and still got the same dim glow.

Does anyone know why it's doing this?

 

[rbelli1]

0.7 volts is way too low to drive any kind of led properly. Especially a white one. How did you measure this?

The LED lighting when you touch it is definitely odd. Can you measure from Earth ground to the led plate?

BoB

 

[Guineafowl]

A pic of the circuit board might help identify the driver type.

The 0.7V could be the driver detecting open circuit and shutting down. About 3V per LED is normal, summed if they’re in series.

Most LED lights I’ve cracked open have had the LEDs in series and required about 180V to light 60 LEDs (240V mains here). Your bench power supply won’t approach that, and I can only guess that the glow is from some kind of capacitive coupling/induced voltage in your body from surrounding mains wires.

Once their forward voltage is exceeded, LEDs require minuscule currents to glow as you describe.

Is your bench supply output fully floating, or ground referenced?