TABLE OF CONTENTS Why are we interested in troubleshooting? Because even the best engineers take on projects whose requirements are so difficult and challenging that the circuits don't work as expected at least not the first time. I don't have data on switching regulators, but I read in an industry study that when disk drives are manufactured, the fraction that fails to function when power is first applied typically ranges from 20 to 70%. Of course, this fraction may occasionally fall as low as 1% and rise as high as 100%. But, on the average, production engineers and technicians must be prepared to repair 20, 40, or 60% of these complex units. Switching-regulated power supplies can also be quite complex. If you manufacture them in batches of 100, you shouldn't be surprised to find some batches with 12 pieces that require troubleshooting and other batches that have 46 such pieces. The troubleshooting may, as you well know, be tough with a new product whose bugs haven't been worked out. But it can be even tougher when the design is old and the parts it now uses aren't quite like the ones you used to be able to buy.
Troubleshooting can be tougher still when there isn't much documentation describing how the product is supposed to work, and the designer isn't around any more. If there's ever a time when troubleshooting isn't needed, it's just a temporary miracle. You might try to duck...
