Good topic (thread). LaserDiscs are one of my passions.
"Magnavox" Magnavision VH-8000 was the 1st to hit the market. In fact it was Made in Holland and rebadged.
PR-7820 was made by "Pioneer" and sometimes rebadged. As far as I know it camed out in 1979.
The "Maganavox/Philips" where very bad players. "Pioneer" where good. "Pioneer" saved the format.
You can restore a PR-7820 to work. I wish me one... industrial looking, top loading, tube generated laser. You need to replace some rubber stuff. But I don't have the money for one.
https://www.youtube.com/watch?v=hdVMUfNdJmI