Author Topic: CX-20 remote LED's (Read 265 times)

bigMouse · « **on:** October 30, 2014, 10:31:42 PM »

Someone handed me a cx-20, fully functional except that the remote LED's for GPS lock, and arming didn't work! Well he said it was fully functional but took that with a pinch of salt!, (he had been fiddling with it!)

A good check of the wiring showed that the motors were connected to the wrong ports and the remote LED harness plug was plugged into the FC the wrong way around! Ok sorted that out, then on pwering up, the green GPS LED flashed as normal, Brief flash of yellow from the arming LED then that led remained off!.

Some voltage checks showed that voltage was present, but difficult to see the type of LED's used, why 3 leads? even tri colour leds only have two wires!, Google search couldn't find these led replacement as a spare part!
So the purpose of this short article is to show how to mend these!

Looking closly at the working LED and powering it from a battery and limiting resistor, you can see two smt leds, both green! So the LEDs are mounted on a tiny pcb! The led is spot glued into a recess in the case.

bigMouse · « **Reply #1 on:** October 30, 2014, 10:35:34 PM »

Carefully wiggling the faulty LED it finally came out of the recess, it was quite easy to remove the plastic clear cover

bigMouse · « **Reply #2 on:** October 30, 2014, 10:43:36 PM »

exposing the pcb, Here you can see the recess where it was mounted, The three wire connections! This Led cluster is actually one yellow LED, and one Red LED, here the yellow LED is powered from an external supply. The Red LED is open circuit. Easy enough to replace with a bit of care.

Moral of the story is, current limiting is within the FC, so plug for these LED's in the wrong way will blow the red led, no doubt gets full voltage!

Also a close up of the pcb, just to show how grotty the PCB and soldering is!