# LED desk lamp needs fixing



## Optimistic_Pess (Jun 3, 2015)

Hi all,

Just thought I'd ask around here, about a LED desk lamp that i got sitting right here that has failed on me.

I've got this Arlec LED Lamp (except that mine is a 3W version) that I bought a while back from my local hardware store for $40.
When I flick the switch it does light up, but its so very dim that no practically useable light is emitted.

Upon removal of the lens cover, the Led star states 'C5050' and the diameter of the star is 20mm.
Here is photo of it http://ocau.com/pix/7unz7
The base has a label that states '230-240V AC 50Hz 3W Led'.
Despite the manual stating that the LED module is non replaceable, I'm fairly certain that it can be with some soldering, etc.

I assuming that any 3w LED on a 20mm star should be fine?

Initially I was told that it wasn't the LED but instead the driver had failed. 
As such, I purchased this 3w 700ma driver which matched the existing driver, and installed it. However the lamp only lights up dimly, same problem as when it was with the original driver. Guessing that this would then indicate that the LED is at fault instead.

Any help would be much appreciated, thanks.


----------



## FRITZHID (Jun 3, 2015)

Could try reflowing the LED, it's worth a shot. Otherwise yes, as long as your driver & LED match up, LED swap is doable. Use heatsink compound.


----------



## poiihy (Jun 4, 2015)

FRITZHID said:


> Could try reflowing the LED, it's worth a shot. Otherwise yes, as long as your driver & LED match up, LED swap is doable. Use heatsink compound.



Reflow LED?? You can do that?? I thought reflowing is only for chips like GPUs.

What's in an LED that can be reflowed? Are there solder connections from the solder pads to tiny wires to the LED die itself?


----------



## FRITZHID (Jun 4, 2015)

The LED itself is soldered to the pads on the star. Usually 2 or 3 pads under the LED. +, -, and a center heat sinking pad. Sometimes heat stress or bad solder joint can cause issues. 
It can be difficult to tell sometimes without a good LED to compare to but if the phosphor looks discolored or burnt, don't waste time w/it, just replace it. Make sure new LED has adequate cooling.


----------



## FRITZHID (Jun 4, 2015)

poiihy said:


> Reflow LED?? You can do that?? I thought reflowing is only for chips like GPUs.
> 
> What's in an LED that can be reflowed? Are there solder connections from the solder pads to tiny wires to the LED die itself?



The LED "die" is set on a grounded substrate, there is a/several very thin wires from the anode substrate to the top side of the chip. Take a look at a power LED thru an eyeloupe or microscope and you'll see it/them.


----------



## Optimistic_Pess (Jun 6, 2015)

Thank you FRITZHID, not too confident in my ability to 'reflow' the LED, as my soldering skills are sub-par. Will however source out a matching 3w LED, and attempt to fix it that way.

Thanks again.


----------



## FRITZHID (Jun 6, 2015)

NP


----------



## FRITZHID (Jul 7, 2015)

Falconstare said:


> Could try reflowing the LED, it's worth a shot. Otherwise yes, as long as your driver & LED match up, LED swap is doable. Use heatsink compound.​



Is there an echo in here? C&P post 2??? Wow.


----------



## more_vampires (Jul 7, 2015)

FRITZHID said:


> Is there an echo in here? C&P post 2??? Wow.



Reflow LED?? You can do that??


----------



## FRITZHID (Jul 7, 2015)

Lol, now you're just being a smartass.


----------



## more_vampires (Jul 7, 2015)

At least you loled.  That was my sole intention.


----------

