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Archive for April 16th, 2014

Arduino Knockoff: Cold Solder Joints!

The knockoff Arduino Pro Mini I used for the strobe photography controller ran the default Blink sketch perfectly, but didn’t respond to its own Reset pushbutton. Probing the Reset line at pin 29 on the microcontroller showed that the pushbutton didn’t pull the +5 V line to ground, so the switch was broken, a trace was broken, or …

Touching the soldering iron to a switch pin caused the whole thing to pop loose. One glance at the pads tells you something’s badly wrong:

Arduino Pro Mini Knockoff - cold solder joints

Arduino Pro Mini Knockoff – cold solder joints

A closeup, rotated a quarter-turn clockwise:

Arduino Pro Mini Knockoff - cold solder joint - detail

Arduino Pro Mini Knockoff – cold solder joint – detail

That’s the nicest picture of cold solder joints you’ve seen in a while, isn’t it?

Resoldering the switch solved the problem and, while the iron was hot, I touched all the microcontroller pins, too, just in case

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