A while back our clothes dryer just stopped working. I knew it had power because the interior light was working, but there was
no display on the control panel. Not being one to call a repairman until I have at least looked for obvious signs of failure, in I
went. It didn't take long since there was the all-too-familiar smell of a burning PCB in the air, and the easiest component to access
was the controller board. This diagnosis was way too easy.
Obviously there is a problem under the relay. Lets see what the other side looks like...
Oh, this doesn't look good. How much current are they trying to push through that little pin? Is this relay even rated for this application? Lets see what else is going on here...
This just keeps getting worse. These resistors get hot. What are they doing right down on the board? Maybe a copper pour would have been a good idea to shield the fiberglass a little but these should be larger and set up off the board in assembly. I wonder how hot the board has been getting? Lets look at the other side again...
OK, really hot. The last thing I need is a fire. Did the heat go beyond the PCB?
Yes! I hope this bracket is made of high-temp plastic.
This is one of the most expensive dryers on the market. These problems could have been easily and cheaply avoided but it seems little thought was put into PCB design, compromising the reliability of an otherwise great product. The complementary washing machine has similar problems. I have a friend who had to replace his hardwood floors throughout the bottom floor of his house because of an arc between two traces which caused the water valve to remain energized when it should not have been. And its not as if there is limited room on these boards, there is plenty to provide more than adequate clearances and widths. My kids have a word for a situation like this... FAIL!
The replacement cost for the board is $168 and I have a feeling many have been sold. A little solder work and new (higher power) resistors did the trick.
You have probably heard about the manager explaining the requirements for the new project to his engineers when one of them went to
the whiteboard and wrote three words: "GOOD", "FAST", and "CHEAP". "Now", he explained, "Pick any two". I think of this every time
I hear about a smoking washing machine PCB, flaming laptop batteries, a shower radio that stops working if it gets wet, or any other
product failure and wonder which 2 were picked. I think I know.
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