01-01-2011, 05:01 AM code 5-91 Troubleshooting Results
All boards are Operational
Board one had an LED that would not light - it was open from the front side board plated through hole to the back side, resulting in an open circuit and no LED response. The fix was scratching and removing the dielectric resin on the front side and re-soldering the through-hole wire on both sides.
Board two had the LED constantly on, but driven to increased brightness. Troubleshooting led to the trace under the second voltage regulator which had a tiny remnant trace fragment shorting out to the adjacent trace. The solution was to remove the trace.
Board three had a tiny short circuit surrounding the solder island at the back side. This was resoldered, solder wicked, and finally a knife was used to sever the ill connect point. Two out of the three boards required a microscope to detect the troubleshooting points of interest.