This looks like an old and inaccurate version of the PAM 571. I may be wrong, but i think that yours looks closest to this model.
But this has significant flaws compared to recent releases. Also this is not an A7750 as the BW is not at 11 - i believe it is some form of ST2555 or something similar as the balance wheel appears to be at 6
As far as the maker, i have no clue