I'll keep it brief. I've dropped a flashlight on the floor, after which the casing broke a bit. The flashlight normally works with a single 1.5V 'D' battery. I was looking into it and tried these steps in a chronological order (number 1 is the one I tried first):
1) Connected a 1.5V 'D' battery (with juice left in it) directly to the circuit with no luck. 2) Connected my power supply set at 3V (that's the MIN voltage I can set it at) directly to the circuit and the LED worked. 3) Connected x2 1.5V 'D' batteries, as a test and worked again.
So after the drop the LED lights up only with x2 batteries at a total of 3V instead of its original 1.5V.
There is nothing wrong with the PCB (it's a very basic design); to test this I repeated 1-3 with wires directly touching the LED. Same results again. So I guess something must have 'changed' in the LED. Is this possible? It's all a bit strange and interesting at the same time :). Some photos follow.
This is my first post here, so I hope all is clear!