how to fix c9 christmas lights. Though these lights are covered by a three-year warranty, it would be more cost-effective to fix them yourself than to cover the shipping costs. I went to Digikey in search of T1 3/4 (5 mm) LEDs in the 800 mcd or higher range and ended up with a nice assortment of the right hues. After much deliberation, I decided to purchase:
404-1096-ND (red) (red)
404-1097-ND (orange) (orange)
C503B-BCS-CV0Z0461-ND (blue) (blue)
C503B-GCN-CY0C0791-ND (green) (green)
404-1092-ND (yellow) (yellow)
The LEDS are strung together in strands of three, each with its own series of connections. If an individual LED in a group fails, the entire group will be dark. Knowing which one (or ones) are harmful is the challenge.
If you can salvage even a small portion of a functional strand, that will make things much simpler. If that’s the case, you can test each bad LED individually by inserting a good LED from the other strand into the good LED’s socket. Please follow these instructions to replace the bad LED in the good strand. If the newly-replaced LED still doesn’t light up, continue to the next one in the string because there may be more than one defective unit.
In the absence of a good strand and any other means of testing the LEDs, you should take them out of the bad strand one by one and inspect the leads to see if they are broken. If the LED is broken, throw it away and get a new one; otherwise, replace it and move on.