The Pioneer PR-7820 was the first mass-produced industrial LaserDisc player, sold originally as the MCA DiscoVision PR-7820.
This unit was used in many General Motors dealerships as a source of training videos and presentation of GM's new line of cars and trucks in the late 1970s and early 1980s.
[1] The PR-7820 is the only player ever sold to either the industrial or consumer market that was entirely designed and engineered by the technicians at MCA Disco-Vision and contained all of their preferred design approaches, such as playing the disc with the laser on top (instead of underneath) and moving the disc radially to provide tracking instead of moving the laser radially.
MCA engineers designed the player at the DiscoVision labs in Torrance, California and Universal-Pioneer mass-produced it in Japan.
It wasn't until 1985/6 that the tangential mirror began to be replaced by electronic correction, first by Yamaha in their first consumer LD player, and eventually, by Pioneer themselves.