I had recently built a word clock for my girlfriend as a christmas present. Now that it has been on for a couple weeks, I am noticing that the wear of the LEDs is not uniform. Of course I would expect some uneven wear over time, but after 3 weeks I would think I should not be able to see any difference.
Here is an imgur album of the clock in question (with pictures of my circuit too): http://imgur.com/a/OdOxl
The phrase at the top "KLUKKAN ER" (the time is) is about half as bright now as the other words. Another word "MINUTUR" is on almost all the time, it is only off for 10 minutes of every hour.
All the words are connected to shift registers and transistor arrays, so they don't turn on immediately when the clock is plugged in. However, "KLUKKAN ER" is tried directly to 5V and GND (with a 220Ohm resistor attached to each LED). I do have a couple of decoupling capacitors on my board where my power comes in, I was hoping that would prevent such a thing. Have I damaged these LEDS since they are connected directly to the power supply?
Does anyone have any idea why this might be happening? Is there something I am missing? Possibly some more information I can provide you with?