Friday, 11 September 2009

Ready, steady,.....

I took the solder paste out of the fridge some hours ago. I had to use pliers to unscrew the clear sealing cap, and to screw on the blue plastic nozzle. Looking at it, I can see patches of yellow in the paste (flux?) as if it isn't properly mixed. You can see it in the picture below under the word "Omni".

The part near the nozzle looks homogenous, though, so I'm not too worried. I probably won't get to the separated paste further down the syringe.

I began to coat the surface-mounting pads on the stepper driver board, carefully doing the pads in the order as given for placing the components so that I wouldn't end up coating the pads for my non-surface-mounted 0.25 ohm resistors. Here is an action shot of paste just about to be applied to the motor pads.

Here is the pasted board - you can see R3 and R16 (below and above the chip location, respectively) left untouched.

Reading those instructions on LED orientation didn't help, because my LEDs have a green "T" marking on the underside, so it wasn't obvious which end is which. I guess if I get it wrong the LED simply won't light!
I went back to RapidOnline, who supplied the LEDs, and looked at the full tech.spec. as given for the part number. The data sheet shows current flow to be in the direction of the "T" from top to stem, so I've aligned the triangle on the LED's data sheet diagram with that on the circuit diagram for the board.

Here is the pasted/assembled board, all ready for frying (except it's tea-time, the cooker is in use, and I'll have to wait!):

I was surprised to find that the board was more robust in this state than I expected, and had no problems moving it to take the photograph.


  1. Fantastically useful blog, Hazel!

    Thanks for all the info and photos. I've been thinking about upgrading to V3, Next time they're in stock at makerbot I think I'll get some boards sent over and have a crack at it, since you seem to be doing OK - then I can probably manage it!


    Dave Reynolds

  2. Oh you spoke too soon! You might want to rethink...
    I'm sure you will when you've read my next entry....