I just finished assembling another ClockTHREE v2 and I realized that there are details that need a bit of clarification (and not captured in the original building instructions). These are related to the orientation of the RGB LEDs and the battery holder for RTC. Not a lot of info, but I felt I have to record these, since I will have to go through the exercise of figuring it out again next time I assemble another C3.
Here are the pictures worth a thousand words.
First the LEDs, shown laying down in the correct orientation. The longest pin, the common node, is closer to the bottom of the PCB (where the ATmega328 is).
Because the LED pins are only 0.05" apart (as opposed to 0.1" in a normal LED, or most other components for that matter), special attention must be paid when soldering these RGB LEDs. There is a tendency of shorting two adjacent pins, so make sure that doesn't happen, by checking with a magnifying glass (or with the ohmmeter). To avoid the possible shorts, I bend the pins outwards, away from each other, as shown below.
Note: One of the advantages of C3 v2 over C3 v1 is that the RGB LEDs can be inserted directly, all the way through, without the need to use the bending tool (as shown in the tutorial for v1).
Second, the battery holder. If you use one like mine, here is how it should be placed.
Note that the board was smartly designed to allow the use of many types of battery holders, including those all-metal ones (either SMD or through-hole).
Also shown are the pull-up resistors required if you solder the DS3231 RTC chip directly to the (back of the) board (and not use the ChronoDot).
Another detail worth mentioning is that the buzzer I am currently using in Wise Clock 3/4 gives a very faint sound when used in C3/C3Jr.