Hi all,

i have six Eyourlife RGB LED Stage par lights. each fixture has 6 x blue, 6 x green and 6 x red led's and each is 3w.

5 of the units work perfectly however one of the units has developed an issue. all of the blue leds flicker and change intensity. when i opened the unit up to check all cables, i noticed the fan changes speed randomly, and when the fan reduces in speed the blue leds flicker and dim but when it speeds up the blue leds stop flickering and go back to normal intensity. so this leads me to believe it is a power fluctuation. i swapped out 1 part at a time with one of my other lights to isolate the issue and as i though i have narrowed it down to the main power supply pcb. so i have two questions, any idea what could cause this on the pcb, an image is attached and is is fixable? and also why does it only cause the blue leds to flicker and not the red or green.



View attachment 167343 thanks for the help.

 

That's a switchmode psu, can you see the number on the 8 pin chip?

These are not essy to fix, main problems are usually capacitors or dry joints around the transformer .

 

Looking at the bridge rectifier diodes they arn't positioned very well, are they adequately soldered underneath? It could be you only have half wave rectification giving excess ripple and lack of regulation.

 

Looking at the bridge rectifier diodes they arn't positioned very well, are they adequately soldered underneath? It could be you only have half wave rectification giving excess ripple and lack of regulation.

Thanks for the response, i shall check all of the joints on the board

 

That's a switchmode psu, can you see the number on the 8 pin chip?

These are not essy to fix, main problems are usually capacitors or dry joints around the transformer .

hello, thanks for the response, unfortunately i cant see any numbers on the chip, unless they are on the underside of it

 

Does anything change if you unplug the fan? They are usually brushless motors with diodes inside. Could be bad as well. It does sound like an intermittent diode issue.

 

If there are no markings on the chip,they clearly don't want you to repair it, it's probably a UC3843/5 series chip, or Viper22a

 

why does it only cause the blue leds to flicker and not the red or green.

Blue LEDs require a higher voltage then green or red. The fluctuations must be dropping below the blue threshold causing them to flicker. The greens and reds should also drop in intensity but may not be that noticeable.
SG

 

have you checked the diodes?