My first job out of college was as a test engineer troubleshooting newly manufactured flight simulators. Because I was young and single, I was put on the night shift, so that the married engineers could be with their families. The simulator I was working on was for the Navy S3-A anti-submarine aircraft. When the system was set up at the training facility -- with the projection system made by somebody else -- the simulator was extremely realistic. Every detail in the flight experience was faithfully reproduced, down to the bumps in the runway. Even system failures were simulated. The simulator consisted of at least two refrigerator–sized computers and a large room filled with interface equipment and simulation hardware.
Most of the electronics were hand wired on to wire-wrap panels. I was asked to troubleshoot one of the panels that was operating intermittently. The wiring in this panel was neatly wired in a horizontal and vertical fashion. This made the wiring look neat, but it caused maximum crosstalk between the wires. All the other panels were wired in a rat's-nest style for minimum coupling between the wires.
My boss was a former US Army sergeant who had no education outside of his military training. When I told him why the circuits on that panel weren't working well, he ignored me. He would say something like, "Well, it was working yesterday." Since I worked nights, I would swap out parts (74-series logic chips) with a presumably higher noise margin until I got it working.
Of course, it would fail again later when the temperature, the phase of the moon, or whatever else changed. My boss accused me of being incompetent, and I got upset and quit.
This entry was submitted by Andrew Morris and edited by Rob Spiegel.
Andrew Morris is a retired electronics engineer who spent most of his career designing automatic test equipment for the defense industry. The last five years of his career were spent designing electronics for automatic dispensers for the paper industry. He has a BSEET degree from Virginia Tech.
Tell us your experience in solving a knotty engineering problem. Send stories to Rob Spiegel for Sherlock Ohms.