Set up the Equipment 1 Remove any test fixture or dust covers that may be on the testhead. If an EFS Board Handler is on the testhead (Mux systems only), remove it. 2 The testhead’s power must be OFF (testhead not booted), but the PDU must be switched on. 3 Rotate the testhead to the service position. 4 Place the DMM near or on top of the testhead. Plug it into a power outlet and turn it on to warm up. The DMM requires adequate warm-up before it is used for calibration: – one hour for the 34401A – two hours for the 3455A – 30 minutes for the 3456A – four hours for the 3458A 5 Open the module doors, install ASRU Card calibration jumpers on all ASRU Cards (in slot 1 of each module) in the testhead, and close the module doors.