(Mostly) Assembling My CupCake Motherboard

The MakerBot CupCake‘s motherboard (RepRap generation 3 motherboard) is Arduino-compatible, connects to all the other boards in the CupCake / RepRap, and has lots of spare connectors to boot.

Ah, spare connectors to prototype, I mean; the spare connectors aren’t needed in order to get the board to boot. Ha ha.

Mostly-assembled CupCake motherboard

I got mine mostly assembled last week. Like every other piece of electronics in my CupCake kit, my motherboard had missing parts — I got five extra 4.7KΩ resistors instead of the five 1.8KΩ resistors. And unfortunately, that was another part for which I couldn’t find replacements at hand — although I did end up sorting and filing a bunch more SMT components while searching.

After waiting a week for the missing resistors as the solder paste was drying out and getting crusty, I gave up and baked the thing without them. I can hand-solder the 1.8KΩ resistors onto the board when they arrive. And because they’re voltage dividers for 5V → 3.3V level conversion to the mini-SD card and pull-ups for the I2C bus — neither of which is needed for basic operation — I can even run the darn thing without them. I just need to get them on there eventually.

Crusty solder paste bakes just as nicely as gooey solder paste, by the way.

Unlabelled R1 on MakerBot Cupcake motherboard

I did spend a while searching for the placement of R1 on the PC board. I eventually found it through a combination of the process of elimination and checking the schematic. As far as I can tell, the name label didn’t make it anywhere onto the silkscreen — can you spot it?

3 Responses to “(Mostly) Assembling My CupCake Motherboard”

  1. Alan Parekh says:

    Nice build log. What is the total cost so far?

  2. Keith Neufeld says:

    Alan, $750 for the prerelease kit, probably $20 for the oil-based “stain” and the clearcoat for the wood panels (not finished and blogged yet), and nothing else but tools I already had for other purposes.

    Note that the current equivalent of the prerelease kit now costs much more than $750.

  3. Alan Parekh says:

    Thanks Keith,

    That is quite a good price for this type of machine. Looks like the circuit board construction is quite well done.

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