FCO 7XXX-F001, Capacitor in some blower assys may overheat/fail

This Field Change Order (FCO) details a mandatory rework procedure for VAX 7XXX systems that utilize specific blower assemblies (DEC P/N 12-35173-01) with serial numbers ranging from 245 to 675. The problem identified is that Capacitor C49 in these blower assemblies can overheat and fail, leading to smoke and caustic odors.

The solution involves a rework of existing blowers on customer systems by removing the suspect Capacitor C49 from the Driver/Servo Module. The procedure, requiring two service engineers, includes safely shutting down the system, removing and disassembling the blower, accessing the Driver/Servo Module, locating and carefully clipping the leads of C49 (ensuring complete removal, not just one lead cut), and then reassembling and reinstalling the blower. Units that have undergone this rework are to be marked with "Green Dots."

Crucially, if Capacitor C49 is found to have already ruptured or exploded, the blower assembly must be replaced, not merely reworked, as the failure may have weakened other components of the Driver/Servo Module, affecting long-term performance. Blowers with serial numbers above 675 or those already marked with "Green Dots" do not require this FCO. Necessary tools include various screwdrivers, diagonal cutters, tweezers, and "Green Dot" labels. The rework activity must be reported, and replacement materials are provided free of charge to customers under warranty.