Power Supply Problems | Agilent Technologies 33120A instruction

Chapter 6 Service

Troubleshooting Hints

Power Supply Problems

SHOCK HAZARD. Only service-trained personnel who are aware

W A R N I N G of the hazards involved should remove the instrument covers. The procedures in this section require that you connect the power cord to the instrument with the covers removed. To avoid electrical shock and personal injury, be careful not to touch the power-line connections.

Check that the input to the supply voltage regulator is at least 1 volt greater than its output.

Circuit failures can cause heavy supply loads which may pull down the regulator output voltage.

Check the main supply voltages as tabulated below.

Power Supply	Minimum	Maximum

+5 Ground Ref.	4.75V	5.25V
+5 Floating	4.75V	5.25V
-5.2 Floating	-5.46V	-4.94V
+18 Floating	17.0V	19.1V
-18 Floating	-19.1V	-17.0V
+5REF Floating	4.75V	5.25V

Some circuits produce their own local power supplies derived from

the main supplies. Be sure to check that these local supplies are 6 active. In particular, the output amplifier and front panel sections

have local supplies. Always check that the power supplies are free of ac oscillations using an oscilloscope.

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Agilent Technologies 33120A manual Power Supply Problems

Contents

Agilent 33120A MHz Function Arbitrary Waveform Generator Service GuidePage Flexible system features Convenient bench-top features Front Panel at a Glance Front-Panel Number Entry MODulation Menu Front-Panel Menu at a Glance Trig Display Annunciators Use the front-panel Input / Output Menu to Rear Panel at a Glance This Book Page Contents Contents Service SchematicsReplaceable Parts Contents Specifications Waveforms Modulation Characteristics General Specifications Product Dimensions Page Quick Start Quick Start Check the list of supplied items One User’s Guide 〈 This Service GuideConnect the power cord and turn on the function generator To prepare the function generator for use If the function generator does not turn on Verify that there is ac power to the function generatorVerify the power-line voltage setting Verify that the power-line fuse is good Remove the power cord . Remove To adjust the carrying handle Set the units to the desired value To cancel the number mode, press Shift CancelTo set the output frequency Enter the magnitude of the desired frequency Enter the magnitude of the desired amplitude To set the output amplitude Enter the magnitude of the desired offset How to change the offset to -1.5 mVdcEnable the offset modify mode To set a dc offset voltage Output the waveform with the displayed duty cycle To set the duty cycleSelect the square wave function Enter the desired duty cycle Select and output the displayed arbitrary waveform To output a stored arbitrary waveformDisplay the list of arbitrary waveforms Move across to the Exprise choice Enter the magnitude of the desired voltage To output a dc voltage Save the instrument state Set up the function generator to the desired configurationTurn on the state storage mode To store the instrument state Recall the stored instrument state Restore the instrument state To rack mount the function generator Quick Start Front-Panel Menu Operation Front-Panel Menu Operation MODulation Menu Front-panel menu reference Front-panel menu reference SYStem Menu Front-panel menu tutorial Messages Displayed During Menu Use Move across to the Power on command on this level Turn on the menuMove across to the SYS Menu choice on this level Cycle the power to restore the default values Move down a level to the Parameter choicesSave the change and turn off the menu Increment the first digit until 300.0 mVPP is displayed Select amplitude adjustment Move down a level to the OUT Term command To select the output terminationMove down a level and then across to the High Z choice To output a modulated waveform Select AMUse the menu to select the shape of the modulating waveform Move down a level verify that Sine is selected Set the modulating frequency to 200 HzSet the modulation depth to 80% Move down a level to the Secured command To unsecure the function generator for calibrationMove across to the CAL Menu choice on this level Move down to the parameters level Calibration Procedures Calibration Procedures Agilent Calibration Services Calibration IntervalTime Required for Calibration Recommended Test Equipment Automating Calibration Procedures Test Considerations Self-Test Performance Verification Tests Quick Performance Check Function Gain and Linearity Verification Frequency Verification AC Amplitude Verification DC Function Offset Verification AC Amplitude Verification Vrms 0.00035 Vrms 15.00 MHz Amplitude Flatness Verification Vrms 0.0061 Vrms AM Modulation Depth Verification Square Wave Duty Cycle Verification Optional Performance Verification Tests Distortion Verification Characters Calibration Security Code To Unsecure the Function Generator Without the Security Code Calibration Message Calibration Count Move across to the Calibrate choice General Calibration/Adjustment ProcedureMove down a level to the Unsecured command Begin the Frequency and Burst Rate adjustment procedure Calculate and save the new value Perform the next adjustment procedure Aborting a Calibration in Progress Frequency and Burst Rate Adjustment AC Amplitude Adjustment High-Z Function Gain and Linearity Adjustment AC Amplitude Adjustment High-Z Frequency Amplitude Modulation Adjustment AC Amplitude Adjustment 50W AC Amplitude Adjustment 50W Adjustment for KHz Setup DC Output Adjustment AC Amplitude Flatness Adjustment Duty Cycle Adjustment AC Amplitude Flatness Adjustment Exiting Output Amplifier Adjustment Optional Error Messages System Error MessagesSelf-Test Error Messages Calibration Error Messages Theory of Operation Theory of Operation Self-test procedures are described in chapter This discussion pertains to the block diagram shown on Block Diagram Overview Output Attenuator Block 8 on block diagram page 129 Schematic on Output Amplifier Block 7 on block diagram page 129 Schematic on 740 R710 R717 740 R710 R711 R715 R716 R719 R720 AM Modulation Square Wave and Sync Block 6 on block diagram page 129 Schematic onBlock 6 on block diagram page 129, schematic on Pre-attenuator Square Wave and Sync Filters Block 5 on block diagram page 129 Schematic on Waveform DAC/Amplitude Leveling/Waveform RAM Block 4 on block diagram page 129 Schematic on Waveform DAC/Amplitude Leveling/Waveform RAM Direct Digital Synthesis DDS Asic Block 2 on block diagram page 129 Schematic on System DACs Block 3 on block diagram page 129 Schematic on Floating Logic Block 1 on block diagram page 129 Schematic on Earth-Referenced Logic Power SuppliesBlock 9 on block diagram page 129 Schematic on Block 10 on block diagram page 129 Schematic on Power Supplies Block 11 on block diagram page 129 Schematic on Display and KeyboardSee Service Service Does the function generator fail self-test? Operating ChecklistIs the function generator inoperative? See To prepare the function generator for use on Call 1-877-447-7278 and ask for Agilent Express Types of Service Available Cleaning Repackaging for ShipmentAgilent suggests that you always insure shipments Surface Mount Repair Electrostatic Discharge ESD Precautions To Replace the Output Protection Fuse F801 To Replace the Power-Line Fuse Unit Fails Self-Test Troubleshooting HintsUnit Reports Error Unit is Inoperative Power Supply Problems Power-On Self-Test Self-Test Procedures 625 112 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