If you look in the MSF service manual at the section for the battery revert power supply, you will find that it has an output signal called AC FAIL [active low] which is connected from the power supply to the station control tray through the station's interconnect board.
This control signal is on pin 6 of J603 on the power supply distribution board. The pin is unused on power supplies that do not have the battery revert option. If you connect your external 'running on UPS' signal to that point, that should accomplish what you want. ------------------------------------------------------- --- In Repeater-Builder@yahoogroups.com, "Keith Dobbins" <[EMAIL PROTECTED]> wrote: "... Was wondering if anyone knew of a way to tell a MSF500 CXB station when the main power failed and a UPS kicked in (External dry contact closure from the UPS is available) ?..."
