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Bad AC to DC Wall Power Adapters
I see a troubling trend developing.  AC to DC power adapters for various electronic devices are failing at an alarming rate.  Iíve had two die lately within a week of each other.  Both were just a few months old.  I hear through the technical ďgrapevineĒ that Iím not the only one who has experienced such failures.
 

A quick look under almost any computer workstation and you will usually find a half dozen different power adapters.  External computer hard drives, laptop computers, computer speakers, cell phone chargers, radios, MP3 player chargers, USB hubs, printers and cordless telephones all use power adapters. The trend lately has been to use a solid state switch mode method to convert the AC to DC.  This method makes for a compact and light weight assembly. But, the more complex electronic circuit inside these little black boxes is not as robust as the older power supplies, which relied on a small transformer to make the voltage conversion.  In most cases, at least based on my own troubleshooting experiences, the failures tend to center on defective electrolytic filter capacitors. 

This puzzles me.  The electrolytic capacitor technology has been around for a long time and their manufacturing should have long ago matured. There is no reason why such devices should fail so quickly.  I have many old complex electronic devices filled with these kind of parts and they are still working fine.  I have one old HP calculator, which is powered by a wall adapter, and the thing is at least 35 years old.   I also have an old power supply which must be over 40 years old and it still works fine.  What has changed?  Clearly the one common factor among all the wall adapters which are failing is that they are being made in China.  Why canít they build devices which last longer than a few months? 

Transformer Type Power Adapters

Switch Mode Power Adapter


January 2011

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