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Agilent Technologies 33120A manual Power Supplies

Models: 33120A

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Page 101

Chapter 5 Theory of Operation

Power Supplies

The ac mains are connected by a fused power entry module, P1. This module incorporates the functions of mains connection, on/off switching, fusing, and line voltage selection (100/120/220 (230)/240). The line voltage selection function of module P1 selects which primary winding of power transformer T1 is energized. The transformer secondary windings are connected to the main pc board through connector J1001.

The floating +5 Vdc and -5.2 Vdc supplies are produced by a bridge rectifier formed by diodes CR1006 through CR1009, filter capacitors C1005 and C1009, and voltage regulators U1003 and U1004. U1005 and CR1011 form a clamp circuit to provide over voltage protection in the event of a mains or transformer failure. The PFAIL and PONRST* signals are derived from the floating +5 Vdc supply. PFAIL is asserted when the raw 5 Vdc supply drops below 6.4 V signaling an unstable power supply condition to the main CPU (U102). Current instrument state information is copied to non-volatile RAM, U106 for future recall if needed. The PONRST* signal holds the main CPU and other logic in a reset state until after the +5 Vdc logic power supply is fully operational. This signal is generally active only following application of line power to the instrument.

The floating –18 volt supplies are produced by bridge rectifier CR1001, filter capacitors C1001 and C1003, and regulators U1001 and U1002. These supplies are used to power all analog circuits in the function generator.

In addition, the vacuum fluorescent display is driven from the – 18 volt 5 supplies. A separate winding of T1 provides a center tapped 6 Vrms filament supply for the display. Bias circuit CR1010, R1009, and C1011 generate the required cathode dc bias for the display filament supply.

The 5 volt earth referenced supply is produced by rectifier CR1051, C1053, and regulator U1051. This supply is earth referenced through the screw used to mount the PC board to the instrument chassis. The GPIB (IEEE-488) and RS-232 computer interfaces and the rear- panel EXT Trigger circuits are powered from this supply. A controlled power-on reset signal for processor U903 is generated by U1052.

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Agilent Technologies 33120A manual Power Supplies

Contents

Agilent 33120A MHz Function Arbitrary Waveform Generator Service GuidePage Flexible system features Convenient bench-top featuresFront Panel at a Glance Front-Panel Number Entry MODulation Menu Front-Panel Menu at a GlanceTrig Display AnnunciatorsUse the front-panel Input / Output Menu to Rear Panel at a GlanceThis Book Page Contents Contents Replaceable Parts ServiceSchematics Contents Specifications Waveforms Modulation Characteristics General Specifications Product Dimensions Page Quick Start Quick Start Connect the power cord and turn on the function generator One User’s Guide 〈 This Service GuideTo prepare the function generator for use Check the list of supplied itemsVerify the power-line voltage setting Verify that there is ac power to the function generatorVerify that the power-line fuse is good If the function generator does not turn onRemove the power cord . Remove To adjust the carrying handle To set the output frequency To cancel the number mode, press Shift CancelEnter the magnitude of the desired frequency Set the units to the desired valueEnter the magnitude of the desired amplitude To set the output amplitudeEnable the offset modify mode How to change the offset to -1.5 mVdcTo set a dc offset voltage Enter the magnitude of the desired offsetSelect the square wave function To set the duty cycleEnter the desired duty cycle Output the waveform with the displayed duty cycleDisplay the list of arbitrary waveforms To output a stored arbitrary waveformMove across to the Exprise choice Select and output the displayed arbitrary waveformEnter the magnitude of the desired voltage To output a dc voltageTurn on the state storage mode Set up the function generator to the desired configurationTo store the instrument state Save the instrument stateRecall the stored instrument state Restore the instrument stateTo rack mount the function generator Quick Start Front-Panel Menu Operation Front-Panel Menu Operation MODulation Menu Front-panel menu referenceFront-panel menu reference SYStem Menu Front-panel menu tutorial Messages Displayed During Menu Use Move across to the SYS Menu choice on this level Move across to the Power on command on this levelTurn on the menu Save the change and turn off the menu Cycle the power to restore the default valuesMove down a level to the Parameter choices Increment the first digit until 300.0 mVPP is displayed Select amplitude adjustmentMove down a level and then across to the High Z choice Move down a level to the OUT Term commandTo select the output termination Use the menu to select the shape of the modulating waveform To output a modulated waveformSelect AM Set the modulation depth to 80% Move down a level verify that Sine is selectedSet the modulating frequency to 200 Hz Move across to the CAL Menu choice on this level Move down a level to the Secured commandTo unsecure the function generator for calibration Move down to the parameters level Calibration Procedures Calibration Procedures Time Required for Calibration Agilent Calibration ServicesCalibration Interval Recommended Test Equipment Automating Calibration ProceduresTest Considerations Self-Test Performance Verification TestsQuick Performance Check Function Gain and Linearity Verification Frequency VerificationAC Amplitude Verification DC Function Offset VerificationAC Amplitude Verification Vrms 0.00035 Vrms 15.00 MHz Amplitude Flatness VerificationVrms 0.0061 Vrms AM Modulation Depth VerificationSquare Wave Duty Cycle Verification Optional Performance Verification TestsDistortion Verification Characters Calibration Security CodeTo Unsecure the Function Generator Without the Security Code Calibration Message Calibration CountMove down a level to the Unsecured command General Calibration/Adjustment ProcedureBegin the Frequency and Burst Rate adjustment procedure Move across to the Calibrate choiceCalculate and save the new value Perform the next adjustment procedureAborting a Calibration in Progress Frequency and Burst Rate AdjustmentAC Amplitude Adjustment High-Z Function Gain and Linearity AdjustmentAC Amplitude Adjustment High-Z Frequency Amplitude Modulation AdjustmentAC Amplitude Adjustment 50W AC Amplitude Adjustment 50W Adjustment for KHz Setup DC Output AdjustmentAC Amplitude Flatness Adjustment Duty Cycle AdjustmentAC Amplitude Flatness Adjustment Exiting Output Amplifier Adjustment Optional Self-Test Error Messages Error MessagesSystem Error Messages Calibration Error Messages Theory of Operation Theory of Operation Self-test procedures are described in chapterThis discussion pertains to the block diagram shown on Block Diagram OverviewOutput Attenuator Block 8 on block diagram page 129 Schematic onOutput Amplifier Block 7 on block diagram page 129 Schematic on740 R710 R717 740 R710 R711 R715 R716 R719 R720 AM Modulation Block 6 on block diagram page 129, schematic on Block 6 on block diagram page 129 Schematic onPre-attenuator Square Wave and SyncSquare Wave and Sync Filters Block 5 on block diagram page 129 Schematic onWaveform DAC/Amplitude Leveling/Waveform RAM Block 4 on block diagram page 129 Schematic onWaveform DAC/Amplitude Leveling/Waveform RAM Direct Digital Synthesis DDS Asic Block 2 on block diagram page 129 Schematic onSystem DACs Block 3 on block diagram page 129 Schematic onFloating Logic Block 1 on block diagram page 129 Schematic onBlock 9 on block diagram page 129 Schematic on Power SuppliesBlock 10 on block diagram page 129 Schematic on Earth-Referenced LogicPower Supplies See Block 11 on block diagram page 129 Schematic onDisplay and Keyboard Service Service Is the function generator inoperative? Operating ChecklistSee To prepare the function generator for use on Does the function generator fail self-test?Call 1-877-447-7278 and ask for Agilent Express Types of Service AvailableAgilent suggests that you always insure shipments CleaningRepackaging for Shipment Surface Mount Repair Electrostatic Discharge ESD PrecautionsTo Replace the Output Protection Fuse F801 To Replace the Power-Line FuseUnit Reports Error Troubleshooting HintsUnit is Inoperative Unit Fails Self-TestPower Supply Problems Power-On Self-Test Self-Test Procedures625 112 Replaceable Parts Replaceable Parts Main PC Assembly 116 117 118 119 120 121 122 123 Display and Keyboard PC Assembly 33120A Mainframe Manufacturer’s List Schematics8 Schematics Block Diagram Pull Off Handle Loosen Captive Sheet 1 132 Sheet 3 Sheet 4 Waveform DAC Schematic 134 Sheet 5 136 Sheet 7 Sheet 8 Output Attenuator Schematic 138 Sheet 9 of 10 Earth Reference Logic Schematic Sheet 10 Power Supplies Schematic 140 Sheet 1 of 1 Display and Keyboard Schematic TOP Side 33120-66521 REV a TOP Side 33120-66502 REV C Manual Part Number