Nighttime makes wonders..... SC12A back to normal... ALL by itself....IS IT NORMAL???
$0.02
Have you searched for "SC12" and read the threads? I see a number of users with similar problems with some "fixes".
1. Exchange the unit....several "strange behavior" threads ended with the poster exchanging the unit. When the thread dead ends it usually means (at least to me) that the problem got fixed.
2. If you have DS12A window sensors, they seem to be extremely critical of magnet positioning. Also you might try another (larger if possible) magnet, on your most problem zone, just as a test. You can get a "door alarm" with magnet for around 4 bucks at Harbor Freight, or surplus. http://www.allelectronics.com/make-a-store/item/MS-14/STANDARD-MAGNETIC-PROXIMITY-SWITCH/1.html
3. Read some of the discussions of SC1200 range, internal antenna, and power cord positioning. Experiment.
4. Others have SC1200 systems working fine. Based on that, you may have a bad console, conditions or structure that cause range problems, unusual interference, hidden installation problems, etc.
5. If you continue with problems, send it back. It is useless if you do not have confidence in it.
And you are probably saying "I shouldn't have to do all this!" true, but X10 markets "value oriented products" to the "value oriented customer". They market the least expensive camaer systems, home automation products, and security systems you can find. Whether we are talking surveillance, home automation, or security, X10 products many times needs some "massaging". This forum is full of posts for antenna mods, repeater and filter recommendations, video camera mods for RF range, light sensitivity, even pan and tilt range, etc. etc. etc.