ÿþAMENDMENT TO SDS 7 OWNERS MANUAL 15 May 1984 OUTPUT PIN CONNECTIONS ON SERIAL NOS. 0  249 ARE THE SAME AS THE OLD SDS 5 i.e. PIN 1 and 2 GROUND PIN 3 HOT (SIGNAL) THIS HAS NOW BEEN CHANGED FROM SERIAL NOS 250 AND ONWARDS ALL ARE WIRED: PIN 1 and 3 GROUND PIN 2 HOT N.B. It is important that the ventilation slots on either side of the unit are not blocked when in use.