Re: Some LEDs Not Lighting During Test

Home Evil Mad Scientist Forums Clock Kits Some LEDs Not Lighting During Test Re: Some LEDs Not Lighting During Test

Windell Oskay

First off, the IC is fine– if it breaks, it will break completely. 

Second: the green and blue LEDs won’t light reliably until you give them ~3.4 V forward voltage. You shouldn’t expect outputs from an Arduino running at 3.3 V to be able to drive them directly.
Problems of the sort you are describing are due to an accidental connection, a broken connection, or a damaged LED– they can sometimes be damaged by heat and/or strain on the legs during installation.

D52 and D62 are also in the group that you are describing– check those five LEDs to see if any of them appear weak or shorted to lines that they shouldn’t be connected to. Test also that each is actually connected to the two lines that it is supposed to be connected to– test LED6 to LED2, for example, to see that D62 lights.