Fluke 5720A service manual AC Voltage Functional Description

Theory of Operation 2

Functional Description Presented by Output Function

The 1100V range is generated by the High Voltage/High Current assembly (A15) operating in conjunction with the Power Amplifier assembly and the High Voltage Control assembly. The 11V range of the DAC assembly is routed to the High Voltage/High Current assembly which amplifies by a gain of -100 to create the 1100V range. Basically the high voltage output is obtained by rectifying and filtering a high voltage ac signal generated by the High Voltage Control assembly operating in conjunction with the Power Amplifier assembly.

2-11. AC Voltage Functional Description

The Oscillator Output assembly (A13) is the ac signal source for the Calibrator. The Oscillator Control assembly (A12), controls the amplitude of this ac signal by comparing it with the accurate dc voltage from the DAC assembly and making amplitude corrections via the OSC CONT line. The frequency of oscillation is phase locked to either the high resolution oscillator on the Current/Hi-Res (A7) assembly or an external signal connected to the PHASE LOCK IN connector on the rear panel. AC voltages are generated in the following ranges:

∙2.2 mV

∙22 mV

∙220 mV

∙2.2V

∙11V

∙22V

∙220V

∙1100V

The 2.2V and 22V ranges are generated by the Oscillator Output assembly and routed to the Calibrator binding posts via relays on the Switch Matrix (A8) and Analog Motherboard assemblies.

The 220 mV range is generated on the Switch Matrix assembly, which resistively divides by ten the 2.2V range of the Oscillator Output assembly. Relays on the Switch Matrix and Analog Motherboard route the 220 mV range to the Calibrator binding posts.

The 2.2 mV and 22 mV ranges are generated on the Switch Matrix assembly. In this mode, the Switch Matrix resistively divides the 2.2V range or the 22V range by 1000 to create the 2.2 mV and 22 mV ranges respectively. Relays on the Switch Matrix and Analog Motherboard route these ranges to the Calibrator binding posts.

The 220V range is generated on the Power Amplifier assembly. In this mode, the Power Amplifier is set for a nominal gain of -10 to amplify the 22V range from the Oscillator Output to the 220V range. The 220V ac range from the Power Amplifier is routed to the Calibrator binding posts by relays on the High Voltage Control assembly and the Analog Motherboard.

The 1100V range is generated by the High Voltage Control assembly operating in conjunction with the Power Amplifier assembly. In this mode, the 22V range from the Oscillator Output is amplified by the Power Amplifier and High Voltage Control assemblies, which create an amplifier with a nominal gain of -100. Relays on the High Voltage Control and Analog Motherboard assemblies route the 1100V ac range to the Calibrator binding posts.

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