This is what I love about the Sherlock Ohms postings. You can turn the equipment upsidedown to find the problem, but in the end, it was a line that had to be drawn darker. This is a common solution to difficult problems -- look at what was difficult at an earlier stage in the equipment's development.
I agree, Chuck. Like many of the Sherlock Ohms blogs, it's hard to imagine how they figured out such an off-the-wall solution. It is certainly not intuitive. The trick here was remembering something odd from the past.
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.
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 _____.
Fifty-six-year-old Pasquale Russo has been doing metalwork for more than 30 years in a tiny southern Italy village. Many craftsmen like him brought with them fabrication skills when they came from the Old World to America.
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