The SCM-1 module consists of three boards connected by an eight wired bus on the front side (not the backplane bus). The boards for SCM-1 are named SCM-A, SCM-B and SCM-C and these names can
be found on the boards.
SCM-A board:
Two relay-boards OPR-1 can be mounted.
One for output for a mechanical speed governor (instead of electronic speed governor), and one
for outputs for mechanical voltage regulation (instead of electronic voltage regulation).
For replacement of OPR-1 the screw for holding SCM-A must be removed, replace the OPR-1 modules, mount SCM-A again to front panel and check that the eight wired bus is still connected from SCM-A to SCM-B.

DEIF SCM-1 Measurement module