Fluke 5725A User Manual

®5725AAmplifierInstruction ManualPN 823435January 1989Rev. 6, 6/96© 1993, 1996 Fluke Corporation, All rights reserved. Printed in U.S.A.All product na

5725AInstruction Manualviii

5725AInstruction Manual5-4

6-1Chapter 6MaintenanceTitle Page6-1. Introduction ... 6-36-2.

5725AInstruction Manual6-2

MaintenanceIntroduction66-3WarningServicing described in this section is to be done by qualifiedservice personnel only. To avoid electrical shock, do

5725AInstruction Manual6-4100V110V115V120VS2 S3 S4VOLTAGESELECTIONFUSEF8A 250V(FAST)200V220V230V240VS2 S3 S4F4A 250V(FAST)JOHN FLUKE MFG. CO., INC.MAD

MaintenanceGeneral Cleaning66-5aq14f.epsFigure 6-2. Accessing the Air FilterGeneral Cleaning 6-4.To keep the 5725A looking like new, clean the case, f

5725AInstruction Manual6-6Access Procedures 6-6.Figure 6-3 shows the location of all major modules in the 5725A. View A is a top view,and view B is a

MaintenanceAccess Procedures66-7wWarningFollow the instructions under "Initial Access Procedure" tomake sure high voltage has been bled off

5725AInstruction Manual6-8CURRENT MODE5725A STANDBYFAULTOVERLOADCABLE OFFPOWER11AMAX2OVPKMAXLEDCR317TP301FRONT PANELTP307TP304LEDCR318HIGH VOLTAGEAMPL

MaintenanceAccess Procedures66-98. Take another DMM reading with the common lead to TP307 and the high lead toTP304 on the Power Supply assembly. Thi

Interference InformationThis equipment generates and uses radio frequency energy and if not installed and used in strictaccordance with the manufactur

5725AInstruction Manual6-10 CAUTIONWHEN REINSTALLING DIGITAL ASSEMBLY,PULL RIBBON CABLE SLACK COMPLETELYINTO CHASSIS. aq17

MaintenanceAccess Procedures66-114. If you want to completely remove the Digital assembly, remove the ribbon cable byreleasing the catches on the boa

5725AInstruction Manual6-12CURRENTAMPLIFIER(A2)BRIDGERECTIFIERHEAT SINKDRESS CABLESAS SHOWNaq18f.epsFigure 6-6. Correct Way to Dress CablesAccessing t

MaintenanceAccess Procedures66-13Accessing the High Voltage Sense Assembly (A6) 6-12.WarningTo avoid electrical shock, do not proceed with the followi

5725AInstruction Manual6-14Accessing the High Voltage Output Transistors 6-13.WarningDuring normal operation, the high voltage heat sinks are atlethal

MaintenanceEnabling Front or Rear Binding Posts66-156. Turn over the 5725A so that the top is facing up.7. Remove the high voltage heat sink assembl

5725AInstruction Manual6-16J222FRONT OUTPUTCABLEREAR OUTPUTCABLECURRENTAMPLIFIER(A2)SECURE UNUSEDCABLEaq23f.epsFigure 6-7. Enabling Front or Rear Bind

7-1Chapter 7TroubleshootingTitle Page7-1. Introduction ... 7-37

5725AInstruction Manual7-2

TroubleshootingIntroduction77-3Introduction 7-1.This section provides troubleshooting information in three parts. First a listing of all5725A fault co

5725AInstruction Manual7-4Table 7-1. 5725A Fault CodesFAULTNO.MESSAGE EXPLANATION201 5725 Self-Test ROM Failure Requires service202 5725 Self-Test RAM

TroubleshootingSelf Diagnostics77-5Table 7-1. 5725A Fault Codes (cont)FAULTNO.MESSAGE EXPLANATION228 5725 Software TRAP 229 5725 Cable Was Off 230 5

5725AInstruction Manual7-6Manual Tests for Fault Isolation 7-4.WarningThe following servicing is to be done by qualified servicepersonnel only. To avo

TroubleshootingManual Tests for Fault Isolation77-7Problems 1 or 2: Fault at Power-Up or When Entering Voltage Standby 7-5.Proceed as follows to isola

5725AInstruction Manual7-8Problem 3: Fault When Entering Voltage Operate 7-6.Proceed as follows to isolate the problem in this condition:1. Suspect t

TroubleshootingTesting the Power Supply By Itself77-93. Remove plug P301 from J301 and inserting it into J303. Now the high voltage powersupply will

5725AInstruction Manual7-10

8-1Chapter 8List of Replaceable PartsTitle Page8-1. Introduction ...

5725AInstruction Manual8-2

List of Replaceable Parts88-3Introduction 8-1.This chapter contains an illustrated list of replaceable parts for the 7-300, 7-600, 12B,and 18 Meters.

OPERATOR SAFETYSUMMARYWARNINGHIGH VOLTAGEis used in the operation of this equipmentLETHAL VOLTAGEmay be present on the terminals, observe all safety p

5725AInstruction Manual8-4Service Centers 8-5.A list of service centers is located at the end of this section.Note This instrument may contain a Nicke

List of Replaceable Parts88-5Table 8-1. Final Assembly (cont)ReferenceDesignatorDescriptionFluke StockNoTot Qty NotesH437 SCREW,PH,P,LOCK,SS,6-32,.750

5725AInstruction Manual8-6aq24f.tifFigure 8-1. Final Assembly

List of Replaceable Parts88-7aq25f.tifFigure 8-1. Final Assembly (cont)

5725AInstruction Manual8-8aq26f.tifFigure 8-1. Final Assembly (cont)

List of Replaceable Parts88-9aq27f.tifFigure 8-1. Final Assembly (cont)

5725AInstruction Manual8-10aq28f.tifFigure 8-1. Final Assembly (cont)

List of Replaceable Parts88-11aq29f.tifFigure 8-1. Final Assembly (cont)

5725AInstruction Manual8-12aq30f.tifFigure 8-1. Final Assembly (cont)

List of Replaceable Parts88-13aq31f.tifFigure 8-1. Final Assembly (cont)

Symbols Marked on EquipmentDANGER — High VoltageProtective ground (earth) terminalAttention — refer to the manual. This symbol indicates that informat

5725AInstruction Manual8-14Table 8-2. A1 Interconnect PCAReferenceDesignatorDescriptionFluke StockNoTot Qty NotesCR1,CR13-15 * DIODE,SI,BV=75V,IO=150M

List of Replaceable Parts88-155725A-1611aq36f.epsFigure 8-2. A1 Interconnect PCA

5725AInstruction Manual8-16Table 8-3. A2 Current Amplifier PCAReferenceDesignatorDescriptionFluke StockNoTot Qty NotesC201,C202,C207,C208,C211,C212,C2

List of Replaceable Parts88-17Table 8-3. A2 Current Amplifier PCA (cont)ReferenceDesignatorDescriptionFluke StockNoTot Qty NotesMP28 INSULATOR, CURREN

5725AInstruction Manual8-18Table 8-3. A2 Current Amplifier PCA (cont)ReferenceDesignatorDescriptionFluke StockNoTot Qty NotesR233,R237,R238,R273RES,MF

List of Replaceable Parts88-195725A-1650aq37f.epsFigure 8-3. A2 Current Amplifier PCA

5725AInstruction Manual8-20Table 8-4. A3 High Voltage Amplifier PCAReferenceDesignatorDescriptionFluke StockNoTot Qty NotesC601 CAP,POLYES,1UF,+-10%,5

List of Replaceable Parts88-21Table 8-4. A3 High Voltage Amplifier PCA (cont)ReferenceDesignatorDescriptionFluke StockNoTot Qty NotesMP668 NUT,HEX,MIN

5725AInstruction Manual8-22Table 8-4. A3 High Voltage Amplifier PCA (cont)ReferenceDesignatorDescriptionFluke StockNoTot Qty NotesR640,R642 RES,CF,100

List of Replaceable Parts88-235725A-1661aq38f.epsFigure 8-4. A3 High Voltage Amplifier PCA

SERVICING SAFETYSUMMANYFOR QUALIFIED SERVICEPERSONNEL ONLYAlso refer to the preceding Operator Safety SummaryDo Not Service AloneDo not perform intern

5725AInstruction Manual8-24Table 8-5. A4 Power Supply PCAReferenceDesignatorDescriptionFluke StockNoTot Qty NotesC301,C302,C321,C322CAP,AL,220UF,+-20%

List of Replaceable Parts88-25Table 8-5. A4 Power Supply PCA (cont)ReferenceDesignatorDescriptionFluke StockNoTot Qty NotesMP310 AIDE,PCB PULL 541730

5725AInstruction Manual8-26Table 8-5. A4 Power Supply PCA (cont)ReferenceDesignatorDescriptionFluke StockNoTot Qty NotesR351 RES,CF,1K,+-5%,0.25W 3434

List of Replaceable Parts88-275725A-1631aq39f.epsFigure 8-5. A4 Power Supply PCA

5725AInstruction Manual8-28Table 8-6. A5 Digital PCAReferenceDesignatorDescriptionFluke StockNoTot Qty NotesC501,C503-511,C516,C518,C519,C521CAP,POLYE

List of Replaceable Parts88-295725A-1650aq40f.epsFigure 8-6. A5 Digital PCA

5725AInstruction Manual8-30Table 8-7. A6 High Voltage Sense PCAReferenceDesignatorDescriptionFluke StockNoTot Qty NotesC100,C121 CAP,POLYCA,1UF,+-10%,

List of Replaceable Parts88-31Table 8-7. A6 High Voltage Sense PCA (cont)ReferenceDesignatorDescriptionFluke StockNoTot Qty NotesJ403 HEADER,1 ROW,.15

5725AInstruction Manual8-32Table 8-7. A6 High Voltage Sense PCA (cont)ReferenceDesignatorDescriptionFluke StockNoTot Qty NotesR154 RES,MF,20K,+-0.1%,0

List of Replaceable Parts88-335725A-1601aq41f.epsFigure 8-7. A6 High Voltage Sense PCA

FIRST AID FORELECTRIC SHOCKFree the Victim From the Live ConductorShut off high voltage at once and ground the circuit. If high voltage cannot be turn

5725AInstruction Manual8-34Table 8-8. A12 Transformer Enclosure AssemblyReferenceDesignatorDescriptionFluke StockNoTot Qty NotesH1 SCREW,FHU,P,LOCK,SS

List of Replaceable Parts88-35aq32f.tifFigure 8-8. A12 Transformer Enclosure Assembly

5725AInstruction Manual8-36aq33f.tifFigure 8-8. A12 Transformer Enclosure Assembly (cont)

List of Replaceable Parts88-37aq34f.tifFigure 8-8. A12 Transformer Enclosure Assembly (cont)

5725AInstruction Manual8-38aq35f.tifFigure 8-8. A12 Transformer Enclosure Assembly (cont)

List of Replaceable Parts88-39Table 8-9. A30 Inductor PCAReferenceDesignatorDescriptionFluke StockNoTot Qty NotesJ1 CONN,MATE-N-LOK,HEADER,4 PIN 51226

5725AInstruction Manual8-40

9-1Chapter 9Schematic DiagramsFigure No. Title Page9-1. A1 Interconnect PCA... 9-

5725AInstruction Manual9-2

Schematic Diagrams9-39Figure 9-1. A1 Interconnect PCA5725A-1611aq48f.eps

1-1Chapter 1Introduction and SpecificationsTitle Page1-1. Introduction ...

5725AInstruction Manual9-4Figure 9-1. A1 Interconnect PCA (cont)

Schematic Diagrams9-59Figure 9-1. A1 Interconnect PCA (cont)

5725AInstruction Manual9-6Figure 9-2. A2 Current Amplifier PCA5725A-1650aq52f.eps

Schematic Diagrams9-79Figure 9-2. A2 Current Amplifier PCA (cont)

5725AInstruction Manual9-8Figure 9-2. A2 Current Amplifier PCA (cont)

Schematic Diagrams9-99Figure 9-2. A2 Current Amplifier PCA (cont)

5725AInstruction Manual9-10Figure 9-3. A3 High Voltage Amplifier PCA5725A-1661aq56f.eps

Schematic Diagrams9-119Figure 9-3. A3 High Voltage Amplifier PCA (cont)

5725AInstruction Manual9-12Figure 9-3. A3 High Voltage Amplifier PCA (cont)

Schematic Diagrams9-139Figure 9-4. A4 Power Supply PCA5725A-1631aq59f.eps

5725AInstruction Manual1-2

5725AInstruction Manual9-14Figure 9-4. A4 Power Supply PCA (cont)

Schematic Diagrams9-159Figure 9-4. A4 Power Supply PCA (cont)

5725AInstruction Manual9-16Figure 9-5. A5 Digital PCAaq62f.eps5725A-1650aq43f.eps100901002 V10 msTYPICAL COMMUNICATIONS ACTIVITYAT PINS 12 AND 13 OF U

Schematic Diagrams9-179Figure 9-5. A5 Digital PCA (cont)

5725AInstruction Manual9-18Figure 9-6. A6 High Voltage Sense PCA100901001 V10 ms100901001 V10 msVOLTAGE STANDBYSTANDBY100901001 V10 msCURRENT STANDBYA

Schematic Diagrams9-199Figure 9-6. A6 High Voltage Sense PCA (cont)

5725AInstruction Manual9-20Figure 9-6. A6 High Voltage Sense PCA (cont)

Schematic Diagrams9-219Figure 9-6. A6 High Voltage Sense PCA (cont)

5725AInstruction Manual9-22Figure 9-6. A6 High Voltage Sense PCA (cont)

Schematic Diagrams99-23aq45f.epsFigure 9-7. A12 Transformer Enclosure Assembly

Introduction and SpecificationsIntroduction11-3Introduction 1-1.The Fluke 5725A Amplifier enhances the 5700A Calibrator in the ac voltage, ac current,

5725AInstruction Manual9-24

1Index—5—5700ACALIBRATOR connector, 2-6, 3-7Connecting to, 2-65725A STANDBY indicator, 3-5—A—A1. See Interconnect assemblyA2. See Current Amplifier as

5725AInstruction Manual2PCAs, 6-5Clearance requirements, 2-5Communication, 5700A and 5725A, 4-8Connectors, (also see binding posts, terminals), 3-5570

Index (continued)3POWER switch, 3-5Problems, 2-5, 7-3—R—Rack mounting, 2-5Rear panel features, 3-6Remote control, 3-3Replacing the fuse, 6-3—S—Selecti

5725AInstruction Manual4

Manual Supplement© 1996 Fluke Corporation. All rights reserved. Printed in the U.S.A. Manual Title: 5725A Supplement Issue: 1Part Number: 823435 Issu

5725A Manual Supplement6/96 1Change #1On page 6-8, replace the first sentence in the Warning with the last sentence in step 6.On page 6-9, paragraph

5725AInstruction Manual1-4Where to Go From Here 1-2.This manual is the operator and service manual for the 5725A. However, because the5725A operates u

Introduction and SpecificationsHow to Use the Manuals11-5How to Use the Manuals 1-3.The following paragraphs describe how each manual addresses the 57

5725AInstruction Manual1-65700A Service Manual 1-8.The 5700A Service Manual is a maintenance guide for the 5700A. The following 5725Atopics are includ

Introduction and SpecificationsSpecifications11-7DC VoltageAbsolute Uncertainty± 5°C from calibration temperatureRelative Uncertainty ± 1°CRange Resol

5725AInstruction Manual1-8AC VoltageRange Resolution FrequencyAbsolute Uncertainty± 5°C from calibration temperatureRelative Uncertainty± 1°C24 Hours

Introduction and SpecificationsSpecifications11-9AC Voltage (continued)Secondary Performance Specifications and Operating CharacteristicsIncluded in U

5725AInstruction Manual1-10AC Voltage (continued)Secondary Performance and Operating Characteristics (continued)Included in Uncertainty Specifications

Introduction and SpecificationsSpecifications11-11ResistanceNominalAbsolute Uncertainty of Characterized Value±5°C from calibration temperature [Note

5725AInstruction Manual1-12Current Derating FactorsNominal Value Value of Derating Factor K for Over or Under CurrentΩTwo-Wire CompI<IL (Note 1)Fou

Introduction and SpecificationsSpecifications11-13DC CurrentRangeResolutionAbsolute Uncertainty±5°C from calibration temperatureFor fields strengths &

iTable of ContentsChapter Title Page1 Introduction and Specifications... 1-11-1. Introduction ...

5725AInstruction Manual1-14AC CurrentRange ResolutionFrequencyAbsolute Uncertainty±5°C from calibration temperatureFor fields strengths >1 V/m but

Introduction and SpecificationsSpecifications11-15AC Current (continued)Secondary Performance Specifications and Operating CharacteristicsIncluded in

5725AInstruction Manual1-16Wideband AC Voltage (Option -03)Specifications apply to the end of the cable and 50Ω termination used for calibration:Range

Introduction and SpecificationsSpecifications11-17General Specifications:Warm-Up time: 2 X the time since last warmed up, to a maximum of 30 minutes.S

5725AInstruction Manual1-18

2-1Chapter 2InstallationTitle Page2-1. Introduction ... 2-32-2.

5725AInstruction Manual2-2

InstallationIntroduction22-3WarningThe 5725A amplifier is capable of supplying lethal voltages. Donot touch the 5700A output terminals. Read this sect

5725AInstruction Manual2-4Table 2-2. Line Power Cord Types Available from FlukeTYPE VOLTAGE/CURRENT FLUKE OPTION NUMBERNorth America 120V/15A LC-1Nort

InstallationService Information22-5Service Information 2-3.Each 5725A Amplifier is warranted to the original purchaser for a period of one yearbeginni

5725AInstruction Manualii4 Theory of Operation... 4-14-1. Introduction ...

5725AInstruction Manual2-6Connecting to the 5700A Calibrator 2-6.Proceed as follows to connect the 5725A to the 5700A:1. Turn the power off for both

InstallationSelecting Line Voltage22-7Selecting Line Voltage 2-7.The 5725A arrives from the factory configured for the line voltage normally appropria

5725AInstruction Manual2-8Accessing the Fuse 2-8.wCautionTo prevent instrument damage, verify that the correct fuse isinstalled for the line voltage s

InstallationConnecting to Line Power22-9Connecting to Line Power 2-9.WarningTo avoid shock hazard, connect the factory-supplied, three-conductor line

5725AInstruction Manual2-10

3-1Chapter 3Operating NotesTitle Page3-1. Introduction ... 3-33

5725AInstruction Manual3-2

Operating NotesIntroduction33-3Introduction 3-1.This section provides setup and operation information for the 5725A Amplifier. Thissection begins with

5725AInstruction Manual3-4Front Panel Features 3-2.Front panel features are called out in Figure 3-1. Each front panel feature is described inTable 3-

Operating NotesRear Panel Features33-5Table 3-1. Front Panel FeaturesA CURRENT OUTPUT Binding PostsThe source of all amplified current if the 5725A i

Contents (continued)iii4-54. High Voltage Sense Assembly (A6)... 4-304-55. Sense Amplifier Section...

5725AInstruction Manual3-6Rear Panel Features 3-3.Rear panel features are called out in Figure 3-2. Each rear panel feature is brieflydescribed in Tab

Operating NotesTurning on the 5725A Amplifier33-7Table 3-2. Rear Panel FeaturesA CURRENT OUTPUT Binding PostsThe source of all amplified current if t

5725AInstruction Manual3-8Turning on the 5725A Amplifier 3-4.WarningTo avoid electric shock, make sure the 5725A is safelygrounded as described in sec

Operating Notes5725A Operating Functions and Modes33-95725A Operating Functions and Modes 3-6.WarningBoth the 5700A and 5725A can produce fatal voltag

5725AInstruction Manual3-10Voltage Standby 3-8.NOOUTPUTCURRENTOUTPUTHILOVOLTAGE MODECURRENT MODE5725A STANDBYFAULTOVERLOADCABLE OFF11AMAX2OVPKMAXNO OU

Operating Notes5725A Operating Functions and Modes33-11Current Standby 3-9.CURRENTOUTPUTHILOVOLTAGE MODECURRENT MODE5725A STANDBYFAULTOVERLOADCABLE OF

5725AInstruction Manual3-12Voltage Operate 3-10.CURRENTOUTPUTHILOVOLTAGE MODECURRENT MODE5725A STANDBYFAULTOVERLOADCABLE OFF11AMAX2OVPKMAXNO OUTPUTHIH

Operating NotesConditions That Activate the 5725A33-13Current Operate 3-11.CURRENTOUTPUTHILOVOLTAGE MODECURRENT MODE5725A STANDBYFAULTOVERLOADCABLE OF

5725AInstruction Manual3-14Conditions That Activate the 5725A 3-12.When the 5725A is connected to the 5700A, and is selected as the amplifier for thea

4-1Chapter 4Theory of OperationTitle Page4-1. Introduction ...

5725AInstruction Manualiv

5725AInstruction Manual4-24-30. Optoisolator Link... 4-184-31. Break-Detect Circ

Theory of OperationIntroduction44-3Introduction 4-1.This section presents theory of operation in increasing level of detail. The 5725AAmplifier is fir

5725AInstruction Manual4-4Figure 4-1. 5725A Overall Block Diagram

Theory of OperationOverall Functional Description44-5• 11A DC Function:The 11A dc function is implemented with a transconductance (voltage in/current

5725AInstruction Manual4-6The 5700A/5725A system uses the following method for ac amplitude control:1. An rms thermal sensor alternately measures two

Theory of OperationOverall Functional Description44-7Operation in the 11A DC Range 4-5.For the dc current function, the 5700A is configured for the dc

5725AInstruction Manual4-8How the 5700A and 5725A Communicate 4-10.The 5725A and 5700A maintain all analog and digital communication over an externalc

Theory of OperationOverall Functional Description44-9Description of the In-Guard Lines 4-12.The following list describes the 11 5725A in-guard lines:•

5725AInstruction Manual4-10Inside the 5725A, B-SENSE LO is buffered by the 5725A, with the equivalentvoltage called MCOM.• B-FEEDBACKDuring ac voltag

Theory of OperationDetailed Circuit Description44-11• High Voltage Power Amplifier Assembly (A3)• Power amplifier• Harness to heat sink and its hig

vList of TablesTable Title Page2-1. Standard Equipment...

5725AInstruction Manual4-12Power Supply Assembly (A4) 4-16.The Power Supply assembly (A4) provides regulated system supplies for all 5725Aassemblies e

Theory of OperationDetailed Circuit Description44-13High Voltage Supply Section 4-17.The high voltage supply allows normal operation from a pair of no

5725AInstruction Manual4-14Switching Section 4-18.MOSFETs Q301/Q317 and Q302/Q318 (each in parallel) are series-switch elements forthe +400V supply. S

Theory of OperationDetailed Circuit Description44-15Current-Limit Section 4-19.Resistors R313 and R329 are current shunts for the high voltage supplie

5725AInstruction Manual4-16Fan Supply Section 4-21.The fan supply uses the same transformer secondary windings as the ±15 and ±20Vsupplies. Its own fu

Theory of OperationDetailed Circuit Description44-17aq19f.epsFigure 4-2. Digital Assembly Block Diagram

5725AInstruction Manual4-18EEROM 4-26.A 2Kb X 8 EEROM (U512) stores 5725A calibration constants plus the date andtemperature of calibration. If the re

Theory of OperationDetailed Circuit Description44-19Break-Detect Circuitry 4-31.The 6303Y divides the 4.9152-MHz crystal frequency by four to create t

5725AInstruction Manual4-20aq20f.epsFigure 4-3. Current Amplifier Assembly Block Diagram

Theory of OperationDetailed Circuit Description44-21• Error Amplifier SectionThe error amplifier section contains three differential amplifiers and a

5725AInstruction Manualvi

5725AInstruction Manual4-22(ICAL, TP208) with the same amplitude and polarity as the current amplifier input voltage.The calibration amplifier output

Theory of OperationDetailed Circuit Description44-23Control and Switching Section 4-38.Refer to page 2 of the Current Amplifier schematic. Relays K201

5725AInstruction Manual4-24High Voltage Amplifier (A3) 4-40.The High Voltage Amplifier assembly, operating with the step-up signal transformers,consti

Theory of OperationDetailed Circuit Description44-25aq22f.epsFigure 4-4. High Voltage Amplifier Assembly Block Diagram

5725AInstruction Manual4-26Integrator 4-42.Op amp U601A is configured as an integrator to reduce the output offset of the inputamplifier circuit. This

Theory of OperationDetailed Circuit Description44-27Transconductance and Cascode Stage 4-45.The output voltage of the input amplifier U602, LVAMP, is

5725AInstruction Manual4-28compensate for the capacitance seen at the gates of the power MOSFETs on the #1 heatsink assemblies. Their sources establis

Theory of OperationDetailed Circuit Description44-29Op amp U606B senses the -400V supply and forces the autobias to the minimum biascondition when the

5725AInstruction Manual4-30to approximately 33Ω/°C by R615. Op amp U603A provides a reference voltage ofabout -0.77V. This reference voltage is applie

Theory of OperationDetailed Circuit Description44-31aq21f.epsFigure 4-5. High Voltage Sense Assembly Block Diagram

viiList of FiguresFigure Title Page2-1. Line Power Cords Available for Fluke Instruments... 2-42-2. Correct

5725AInstruction Manual4-32• Serial Interface/Guard Crossing SectionThe serial interface/guard crossing section consists of an RS-232 interface integ

Theory of OperationDetailed Circuit Description44-33VR105 reduce apparent supply voltage seen by U102. Transistors Q105 and Q106 alongwith R131/C117 a

5725AInstruction Manual4-34latch up by eliminating positive feedback resulting from positive output voltages fromU100. Op amp U105 is simply a low-noi

Theory of OperationDetailed Circuit Description44-35IC U156 is a dac whose digital input is under microprocessor control via data latchU155. The +15V

5725AInstruction Manual4-36Relays K102 and K103 provide switching that allows direct drive of the sense amplifierand its calibration circuitry by the

Theory of OperationDetailed Circuit Description44-37AC Line Voltage Selection Section 4-60.In addition to the primary power switch, S401, this section

5725AInstruction Manual4-38

5-1Chapter 5Calibration and VerificationTitle Page5-1. Introduction...

5725AInstruction Manual5-2

Calibration and VerificationIntroduction55-3Introduction 5-1.The 5725A is calibrated at the factory before shipping. Calibration is traceable to theU.