Originally Posted by THX-1138
Has anyone come up with a way to isolate the units?
On audio connections you can use a hum-blocker that is used in car audio installations. It is just a 1:1 transformer that decouples the ground loop that causes hum in high powered audio installations.
Google "Ground.Loop.Isolator", They're about $3-$5 ...
On video connections there are limited choices due to the bandwidth needed for baseband RCA video / S-Video. Not to mention the inversion of signal if you tried to just cut the ground (LOL).
Makes a mess of a picture on Baseband/S-Video.
I used to use old IF-Transformers from radar boards that had to much of It's silicon componentry blown to be viable as a board level repair candidate
RF connections can be decoupled by simply connecting to 75-Ohm to 300-Ohm baluns back-to-back.
Just solder, or use two 1/8" screws&nuts to connect the 300-Ohm ends to each other. Then tape or heatshrink the connections.
I would solder, then heatshrink the two connections.
Then solder a 3/8" ring lug to the edge of a piece of tim foil.
I slid the ring lug over one threaded 75-Ohm end and wrap the entire pair to shield it. Then trim the excess making sure to leave a 1/4 gap on the other end without the ring lug.
Finished up with a piece of heatshrink over the whole pair with a popsicle stick or something stiff to unite the pair into one piece.
Lastly, tighten a nut over the end with the ring lug.
Use that shielded end on the negative ground unit of course.
There is a slight loss of course, but it is fine for the channnel 2/3/4 output.
As to your equipment compatibility.
You need to (or have a friend) test the negative supply lead entering all the equipment you'll use in an installation against any chassis-related connections like the casing of RCA audio/video jacks, casings of S-Video jacks, and threaded barrels of RF F-Connector jacks, etc.
Most of what you listed should be fine as they are already made to be used in an American 12-Volt enviroment, and are almost certainly negative ground.
Where people used to get in trouble would be china/taiwan/etc. D-Battery TV's that had wal-warts or power-bricks. They were cheap and they just "assumed" they would work... A penny saved would turn into a dollar burned so to speak.
I'd test that older Panasonic D-Battery TV before I connected it to anything.