On the A16, look at the side of the unit that connects to the XA; there is a small silver contact (that corresponds to a pin on the camera) which is located towards the top of the gun. If you push this contact in with a ball point pen the neon light should pop up and the flash should charge up in a few seconds. There are 2 small electrical contacts on the same side of the gun , they are towards the bottom of the unit one on top of the other about 3/8 of an inch apart; if you short these contacts out with a paper clip the flash should fire. I use this method to test my A16 sometimes but I'm sure Olympus or a camera repair technician might frown upon such a fool hardy action, so I don't recomend you do it too often!!!