Check this great review out: https://www.arcade-projects.com/threads/axunworks-jj-cbox-a-no-shill-review.17849/
Yes it does have a PSU inside. @drfunk2k or @djsheep may be able to answer detailed questions
Very smooth and easy transaction when I picked up one of the Neo Geo carts he was selling. Great communication - would buy from him again for sure
Thanks @BanishingFlatsAC !