LED light repair

Hi..
i have a 5W led light which recently stopped working, after opening the top i found that 1 led was burned, so i just removed that led and soldered the points. Now its working ok. So i am wondering did the led driver automatically limiting the current.

skmdmasud said:

So i am wondering did the led driver automatically limiting the current.

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If the lamp still works then the driver is limiting the current. Depending on the design of the driver the current now may or may not be the same as it was previously. If the current now has increased then the life of the remaining LEDs will be reduced.

Nice job there. I wish more people would do this sort of repair, stop a lot of wasted stuff going to landfill....

If current is limited, the limiting circuit will likely be dissipating more heat (3mlre volts at rated current). The excess heat may (MAY) shorten life of that circuitry. The best way to find out is to plug it back in and let us know how it survives.

if you knew the amount of current those LEDs were being driven with, you could calculate a suitable resistor value to put in in place of the one that burned out, for instance, 100mA would give 3.6V/0.1A=36 ohms, and the resistor would dissipate 3.6V*0.1A=.36W, so a half watt resistor would work there... that resistor might also act as somewhat of a fuse in case an LED in the string shorts rather than failing open circuit.

i just did a quick calculation of 5W/9LEDS=0.555W... .555W/3.6V=.154A so 150mA would make it 24 ohms, dissipating .555W, so a 1 watt resistor would be required

gophert said:

If current is limited, the limiting circuit will likely be dissipating more heat (3mlre volts at rated current). The excess heat may (MAY) shorten life of that circuitry. The best way to find out is to plug it back in and let us know how it survives.

Click to expand...

Possibly not. That lamp looks as though it has a flyback circuit, much like in modern transformers. All flyback circuits need feedback, and lamps with flyback supplies usually use current feedback.

Shorting out one LED will generally just reduce the power consumption as the current will be the same and the flyback will just run less.

gophert said:

If current is limited, the limiting circuit will likely be dissipating more heat (3mlre volts at rated current). The excess heat may (MAY) shorten life of that circuitry. The best way to find out is to plug it back in and let us know how it survives.

Click to expand...

It is running for few days now, did not notice any thing abnormal. Even the brightness is quite the same .