Three year old JVC camera. Camera is in box on front of business. Camera started showing on monitor today getting very dim. Pulled camera from housing checked power supply, even load tested. Checked iris connections and coax connector. All good. Went to video card changed camera to input on another channel, same view showing on other channel too. This might be a clue but showing up on screen/monitor is small purple dot near center of picture regardless of which input I change it to. Picture is very dark like night time. this problem started occurring in broad daylight. Even though camera is in lighted area it shows up as total darkness tonight. Any ideas? Have you seen this before with JVC Color camera.