Mains plug & filter (A)
It is the main power inlet for both IPHT and RASB. The right voltage can be set by turning the fuse holder, with the arrow of the desired mains supply voltage imprinting is aligned with the mark. Today both units are operated with 2 Fuses TT 1A 250V (very slow fuses).
It is mounted on the plate at backside and it is fixed with two screws.