Riker

I have just acquired a couple of GET PIR wireless Cameras that only stay on for about 20seconds on activation. The board # on these is Global Tech GT670M3. Does anyone have experience of these cameras and know of a way to increase the time on? I have tried adding resistors to the pot on the board but this does not work I would be grateful for any suggestions as I would like to use these as wildlife cameras. Thanks, Ry