I was at my clients today (im a computer guy), he has a 4 camera system DVR. I installed a USB KVM switch so he could switch between his PC and his DVR, so he won't need to swap the VGA cable back and forth anymore.
After I installed the cable, we had 1 camera that was somewhat distorted. I unplugged a cable then plugged it back in, and now I have 2 cameras distorted. I removed the KVM and the same problem existed so I plugged the KVM back in. I checked all wires and nothing seems to interfere. I then unplugged all 4 cams (cat5 baluns) and played with different configurations and here are the results (which did not help me in a fix yet).
Camera 1 works perfect all the time regardless of what is plugged in.
Camera 2 works perfect when three to four total cams are plugged in, but will get distorted if two or less cams are plugged in.
Camera 3 is blurry all the time, but is most distorted when plugged in alone, then less distorted with the second plugged, then even more less with third is added etc.
Camera 4 has same symptoms as 3.
If I unplug camera 4 and then just touch the BNC connector to the back metal area of the DVR, camera 4 gets just a bit less distorted and vise versa with camera 3.
Does this ring any bells? Thanks.