Hi! Recently I bought a Datron 4000A calibrator with died internal battery. After the battery replacement I check a calibrator functionality but found only Ohms mode working. On the voltage and current modes it have a nearly zero output on the all ranges. I checked the Reference and PWMs functionality and it's was fine. The main problem I found is zeroed NVRAM constants, after that a normal calibration is impossible. On the Reference/PWM Board there is a switch for alternative mode calibration. But it is not clear what to do the next. Please, can anyone else have the Datron 4000,4200,4800,4910 e.t.c. Service Manuals or methodics for initial calibration after the battery replacement? Thank you, Mickle T.