Fixing the sensor

As you will recall from the last post, I had broken a couple of pins on one of the three opto-interrupter limit sensors that came with the kit.  I ordered a replacement sensor from Mouser.com, which arrived in a few days.  I should have really ordered several, as the shipping cost was substantially more than the cost of the individual sensor.

I purchased some soldering equipment from Frys and enlisted the help of a couple of my friends from work.  No shortage of people who know about soldering here in Silicon Valley.  One coworker had already helped me pull out the pin casing of the damaged sensor, exposing the two pins that had been broken off.  Another provided some heat shrink and resoldered the damaged sensor, keeping the new one as a spare.  We couldn't quite finish the job, as I had to run to pick up my daughter from school.  All I had to do was borrow my neighbor's heat gun (basically a high-powered blow dryer) and shrink the tubing to cover up the exposed solder joint.  Didn't think I needed any instructions for that.  After all, how hard could it be?

Hmm, guess I held the gun a little too close. :-)  Good thing I had a spare.  So the next day I enlisted my neighbor's help on the remaining sensor, and he did an expert job with the soldering.  The picture below is a little deceptive.  The two diagonally opposed corner pins were brought together and soldered to the black wire.  The yellow wire is actually going over one of those two pins, but it's kind of hard to see.  Still not done, though, as the heat shrink I had gotten wouldn't shrink enough for a tight fit onto the wire.

Another day, another trip to Frys for more heat shrink, and a little more help from my neighbor and we finally had the third sensor mounted.  This weekend I should hopefully be able to to finish the build.