Schism does not per se make a Sacrament invalid, neither does heresy.
The Anglicans do not have valid orders because they long ago changed the form for the sacrament; form is one thing required for validity. Also, then lack the requisite intention (for a number of reasons).** But I would say that Anglicans, like other Protestants, do not see priests as having that special separate role that the Catholic Church teaches.** The declaration that Anglican orders are null and void is considered an example of a dogmatic fact, an infallible judgment of the prudential order.
newadvent.org/cathen/01644a.htm
The Orthodox believe in all seven Sacraments, and they have the same view of the priesthood as Catholics. They are not in the same situation as the Anglicans because their form and intention remains valid, from a Catholic point of view. The Catholic Church has stated that the Orthodox have all seven Sacraments.