Problems with a malfunctioning key fob may not come as that big of a surprise when the device is ten years old, but when the Mercedes garage wants to rip you off for £250 ($376 US) to replace the unit, that’s just not cool.
Electronics Production Engineer Jon Hall offered to take a look at the fob when a relative complained about having difficulties with the alarm/immobiliser and had already tried replacing the battery with no luck.
“When I opened up the key fob, the problem was obvious as the push button fell onto the floor. The surface mount leads had sheared out of the soldered joint. You can see in the photo below the four pads where the push button used to reside….
…and closer detail in the picture below:
After adding a little flux I re-tinned the pads:
and soldered the component back into position:
My advice: Apply more solder when you know a component will be subjected to mechanical stress, even better use through hole components, not surface mount!”
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