That's a very good question, dutchman. I've heard tons about contrl panels failing in equipment such as washers, dishwashers and refrigerators, but I haven't heard much about what caused the failures. Users shell out the bucks, replace the control panels and move on.
I womder if tin whisker growth have anything to do with it. (See: http://www.eetimes.com/design/military-aerospace-design/4230652/Understanding-and-mitigating-tin-whiskers?cid=NL_MilAero&Ecosystem=military-aerospace-design )
Yes, Tim, there are plenty of washer stories in both the Sherlock and Monkey blogs, but most of the posts find difficulty with the control panels rather than the mechanical operation of the washer. Even with the wear and tear, washers are remarkably durable. It's the relatively new electronics that seem to create most of the problems.
We used a Maytag for about 7 years before the unit would not work. It seems the wiring to one of the pc boards was very loose so I recconnected the wires but the washer would still not wash. I replaced all of the power transistors on the motor control board to no avail. I finally purchased a combination motor and motor control board from Ebay, installed it and it has been working fine ever since. I was glad that I did not have to "junk" the entire unit causing global waste instead of repairing the washing machine. The loose wires appeared to be some kind of tachometer feedback to the motor control board. The loose wires may have taken out the motor microcontroller but I was not sure.
Washers do see a lot of force and friction during the normal operation. It is probably one of the hardest working pieces of equipment in a house. That may be the main reason that there are so many articles in Sherlock Ohms about washer failures.
This is a good example of the pitfalls of trying to validate a design solution with a test which doesn't adequately represent real-world conditions. With a small amount of water and no clothes, replacing the pressure switch appeared to work. It only became apparent that the pressure switch wasn't the problem when you tried to use the washing machine to actually wash clothes! Let those who are tasked with developing test and validation programs beware.
When my electric dryer wouldn't heat up I would have bet money it was because the heating element went bad. It took me about an hour to tear it all apart to get to where I could ohm out the element. It tested good. I took the inpection panel off from behind the controls in a matter of seconds to see the control had melted.
Wal-Mart will hold its second Made in the USA Open Call July 7-8, at its headquarters in Bentonville, Ark. The event will be a repeat effort by the world’s biggest seller of consumer goods to increase the amount of US-made products it sells in Wal-Mart stores, in Sam’s Club members-only wholesale outlets, and on walmart.com.
From design feasibility, to development, to production, having the right information to make good decisions can ultimately keep a product from failing validation. The key is highly focused information that doesn’t come from conventional, statistics-based tests but from accelerated stress testing.
There’s a good chance that a few of the things mentioned here won't fully come to fruition in 2015 but rather much later down the line. However, as Malcolm X once said, "The future belongs to those who prepare for it today."
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.