Lynx II Motherboard C104471-001 Rev A.1. Manufactured around November 1991.
We've also go other Atari Lynx Motherboard Revisions documented.
Sourced from: File:Atari-Lynx-II-Motherboard-Shielding.jpg, File:Atari-Lynx-II-Motherboard.jpg, File:Atari-Lynx-II-Motherboard-Back.jpg