I've searched for an answer to this question, perhaps with the wrong terminology.
I have several little DIY boards around the house with a small on board 3v3 regulator. I feed these with old 5v phone chargers. Lately I had 3 of them break, all of these were genuine Samsung brand 0.7A USB chargers (older type where the USB lead is permanently connected to the housing, before they started making them detachable).
And with break i mean, the samsung supply stops supplying 5v, its more like 3v now, both open circuit and under load. My boards stop working altogether as well (although hooked up to my desktops 5v they still work fine).
Now the question is, are these switching power supplies breaking of old age ? or aren't they designed to supply a comparatively small load of 20mA 24/7
Any input would be appreciated!