Insufficient contrast is a very subtle failure mode indeed. The system goes from functioning to intermittant to failed and nothing shows up as the cause. Hartridge has a similar problem with the linear encoders in their fuel injector system teststands, except that it is dirt, not fading. The normal fix is a new encoder for about $450, and two hours wait, and hope the new encoder is in stock. My cheap fix was to clean the scale in the encoder with denatured alcohol and a soft lense wipe tissue. Materials cost is about ten cents and the labor time is about five minutes and no recalibration is needed. But the profit is less, so the customer gets the _____.
I guess in today's highly regulated environment, this temporary black pen fix would not be enough. In addition to solving the problem immediately, a root-cause countermeasure would also be needed to be performed by the equipment manufacturer so this problem would not occur again years later.
Focus on Fundamentals consists of 45-minute on-line classes that cover a host of technologies. You learn without leaving the comfort of your desk. All classes are taught by subject-matter experts and all are archived. So if you can't attend live, attend at your convenience.