Fluke 5790A User manual

®
5790A
AC Measurement Standard
Service Manual
PN 893292
January 1992 Rev.5, 1/07
© 1992-2007 Fluke Corporation, All rights reserved. Printed in USA
All product names are trademarks of their respective companies.

LIMITED WARRANTY AND LIMITATION OF LIABILITY
Each Fluke product is warranted to be free from defects in material and workmanship under normal use and
service. The warranty period is one year and begins on the date of shipment. Parts, product repairs, and
services are warranted for 90 days. This warranty extends only to the original buyer or end-user customer of
a Fluke authorized reseller, and does not apply to fuses, disposable batteries, or to any product which, in
Fluke's opinion, has been misused, altered, neglected, contaminated, or damaged by accident or abnormal
conditions of operation or handling. Fluke warrants that software will operate substantially in accordance
with its functional specifications for 90 days and that it has been properly recorded on non-defective media.
Fluke does not warrant that software will be error free or operate without interruption.
Fluke authorized resellers shall extend this warranty on new and unused products to end-user customers
only but have no authority to extend a greater or different warranty on behalf of Fluke. Warranty support is
available only if product is purchased through a Fluke authorized sales outlet or Buyer has paid the
applicable international price. Fluke reserves the right to invoice Buyer for importation costs of
repair/replacement parts when product purchased in one country is submitted for repair in another country.
Fluke's warranty obligation is limited, at Fluke's option, to refund of the purchase price, free of charge repair,
or replacement of a defective product which is returned to a Fluke authorized service center within the
warranty period.
To obtain warranty service, contact your nearest Fluke authorized service center to obtain return
authorization information, then send the product to that service center, with a description of the difficulty,
postage and insurance prepaid (FOB Destination). Fluke assumes no risk for damage in transit. Following
warranty repair, the product will be returned to Buyer, transportation prepaid (FOB Destination). If Fluke
determines that failure was caused by neglect, misuse, contamination, alteration, accident, or abnormal
condition of operation or handling, including overvoltage failures caused by use outside the product’s
specified rating, or normal wear and tear of mechanical components, Fluke will provide an estimate of repair
costs and obtain authorization before commencing the work. Following repair, the product will be returned to
the Buyer transportation prepaid and the Buyer will be billed for the repair and return transportation charges
(FOB Shipping Point).
THIS WARRANTY IS BUYER'S SOLE AND EXCLUSIVE REMEDY AND IS IN LIEU OF ALL OTHER
WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY IMPLIED WARRANTY
OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. FLUKE SHALL NOT BE LIABLE
FOR ANY SPECIAL, INDIRECT, INCIDENTAL, OR CONSEQUENTIAL DAMAGES OR LOSSES,
INCLUDING LOSS OF DATA, ARISING FROM ANY CAUSE OR THEORY.
Since some countries or states do not allow limitation of the term of an implied warranty, or exclusion or
limitation of incidental or consequential damages, the limitations and exclusions of this warranty may not
apply to every buyer. If any provision of this Warranty is held invalid or unenforceable by a court or other
decision-maker of competent jurisdiction, such holding will not affect the validity or enforceability of any other
provision.
Fluke Corporation
P.O. Box 9090
Everett, WA 98206-9090
U.S.A.
Fluke Europe B.V.
P.O. Box 1186
5602 BD Eindhoven
The Netherlands
11/99
To register your product online, visit register.fluke.com

i
Table of Contents
Chapter Title Page
1 Introduction and Specifications......................................................... 1-1
1-1. Introduction........................................................................................... 1-3
1-2. Service Information .............................................................................. 1-3
1-3. Symbols ................................................................................................ 1-3
1-4. Safety Instructions ................................................................................ 1-4
1-5. Input Source Limits .......................................................................... 1-4
1-6. Power Source.................................................................................... 1-4
1-7. Proper Fuse Usage............................................................................ 1-4
1-8. Grounding of the 5790A................................................................... 1-4
1-9. Proper Power Cord Usage ................................................................ 1-4
1-10. Do Not Operate in Explosive Atmosphere....................................... 1-4
1-11. Do Not Attempt to Operate if Protection may be Impaired.............. 1-4
1-12. Do Not Remove the Cover unless Qualified .................................... 1-5
1-13. Do Not Service Alone ...................................................................... 1-5
1-14. Use Care when Servicing with Power On ........................................ 1-5
1-15. Specifications........................................................................................ 1-5
2 Theory of Operation ............................................................................ 2-1
2-1. Introduction........................................................................................... 2-5
2-2. 5790A Overview................................................................................... 2-5
2-3. Functional Block Diagram Discussion ................................................. 2-5
2-4. Digital Section Overview...................................................................... 2-6
2-5. Analog Section Overview..................................................................... 2-6
2-6. System Interconnect Detailed Circuit Description ............................... 2-9
2-7. Digital Motherboard Assembly (A4)................................................ 2-9
2-8. Transformer Assembly (A22)........................................................... 2-9
2-9. Analog Motherboard Assembly (A3)............................................... 2-9
2-10. Rear Panel I/O Assembly (A21)....................................................... 2-10
2-11. Rear Panel Power Supplies .......................................................... 2-10
2-12. Rear Panel Digital Control ........................................................... 2-10
2-13. Clock Regeneration Circuit.......................................................... 2-10
2-14. IEEE-488 (GPIB) Interface.......................................................... 2-10
2-15. RS-232-C Interface ...................................................................... 2-11
2-16. Rear Panel CPU Interface ............................................................ 2-12

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2-17. Digital Section Detailed Circuit Description ........................................ 2-12
2-18. Digital Power Supply Assembly (A19)............................................ 2-12
2-19. +5 V Power Supply ...................................................................... 2-12
2-20. ±12 V Power Supplies.................................................................. 2-12
2-21. +35 V Power Supply .................................................................... 2-13
2-22. +75 V Power Supply .................................................................... 2-13
2-23. +35 V and +75 V Shut-Down Circuit .......................................... 2-13
2-24. CPU Assembly (A20)....................................................................... 2-14
2-25. Power-Up and Reset Circuit......................................................... 2-14
2-26. Clock Generation ......................................................................... 2-17
2-27. Watchdog Timer .......................................................................... 2-17
2-28. Address Decoding and DTACK (Data Acknowledge) ................ 2-18
2-29. Interrupt Controller ...................................................................... 2-19
2-30. Glue Logic.................................................................................... 2-19
2-31. RAM (Random-Access Memory) ................................................ 2-19
2-32. ROM (Read-Only Memory)......................................................... 2-19
2-33. Electrically-Erasable Programmable Read-Only Memory
(EEPROM)................................................................................... 2-20
2-34. DUART (Dual Universal Asynchronous Receiver/Transmitter)
Circuit........................................................................................... 2-20
2-35. Clock/Calendar Circuit................................................................. 2-20
2-36. Clock Filter Circuit ...................................................................... 2-20
2-37. CPU to Rear Panel Interface ........................................................ 2-20
2-38. CPU to Front Panel Interface ....................................................... 2-21
2-39. Front Panel Assembly (A2) .............................................................. 2-21
2-40. Clock Regeneration Circuitry ...................................................... 2-21
2-41. Refresh Failure Deject Circuitry .................................................. 2-21
2-42. Decoding and Timing Circuitry ................................................... 2-22
2-43. Control Display Circuitry............................................................. 2-22
2-44. Measurement Display Circuitry ................................................... 2-23
2-45. Keyboard Scanner Circuitry......................................................... 2-24
2-46. LED Circuitry .............................................................................. 2-24
2-47. Keyboard Assembly (A1)................................................................. 2-25
2-48. Analog Section Detailed Circuit Description ....................................... 2-26
2-49. Filter Assembly (A18)...................................................................... 2-26
2-50. Unregulated CH Supplies............................................................. 2-27
2-51. Unregulated LH Supplies............................................................. 2-27
2-52. Unregulated ±17 SR Supplies ...................................................... 2-27
2-53. Triac Circuit ................................................................................. 2-27
2-54. FR1 Supplies ................................................................................ 2-27
2-55. Unregulated FR1 Supply.............................................................. 2-28
2-56. FR2 Supplies ................................................................................ 2-28
2-57. Regulator/Guard Crossing Assembly (A17)..................................... 2-28
2-58. Voltage Regulator Circuitry......................................................... 2-28
2-59. Regulated LH Supplies ................................................................ 2-29
2-60. Regulated ±17 S Supplies ............................................................ 2-29
2-61. Regulated ±15 CH Supplies ......................................................... 2-29
2-62. FR1 Supply .................................................................................. 2-29
2-63. FR2 Supply .................................................................................. 2-30
2-64. Guarded Digital Control Circuitry ............................................... 2-30
2-74. Transfer Assembly (A10) ................................................................. 2-33
2-75. Input Signal Paths ........................................................................ 2-33
2-80. Precision Amplifiers..................................................................... 2-35
2-81. Thermal Sensor Circuit ................................................................ 2-36
2-82. Digital Interface and Control ....................................................... 2-36

Contents (continued)
iii
2-83. A/D Amplifier Assembly (A15)....................................................... 2-37
2-84. Chopper Circuit............................................................................ 2-37
2-90. A/D Amplifier Circuits ................................................................ 2-39
2-96. Digital Control and Power Supply ............................................... 2-41
2-97. DAC Assembly (A16) ...................................................................... 2-41
2-98. DAC Assembly Reference Circuitry............................................ 2-42
2-99. Duty-Cycle Control Circuit.......................................................... 2-43
2-100. DAC Filter Circuit ....................................................................... 2-44
2-101. DAC Output Stage ....................................................................... 2-44
2-102. Sense Current Cancellation Circuit.............................................. 2-44
2-103. Linearity Control Circuit.............................................................. 2-44
2-104. Negative Offset Circuit ................................................................ 2-45
2-105. Wideband Module (A6, Option -03) ................................................ 2-45
2-106. Input Signal Path for the Upper Four Ranges .............................. 2-47
2-107. Input Signal Path for the Lower Four Ranges.............................. 2-47
2-108. DC Offset Feedback for Amplifier U3 (Lower Ranges).............. 2-48
2-109. RMS Sensor Circuit ..................................................................... 2-48
2-110. Transfer Methodology.................................................................. 2-48
2-111. DC Offset Feedback for the RMS Sensor Amplifier ................... 2-48
2-112. Range Comparator ....................................................................... 2-49
2-113. Wideband Frequency Counter...................................................... 2-49
2-114. Digital Control ............................................................................. 2-50
2-115. A6A2 Input Protection Module.................................................... 2-50
3 Calibration and Verification................................................................ 3-1
3-1. Introduction........................................................................................... 3-3
3-2. Calibration Cycle.............................................................................. 3-3
3-3. Periodic and Service Calibration ...................................................... 3-3
3-4. Full or Range Calibration ................................................................. 3-3
3-5. Automating Calibration and Verification ......................................... 3-3
3-6. How Calibration Memory is Organized ........................................... 3-4
3-7. How to Use the Calibration Menus .................................................. 3-5
3-8. The Cal Menu............................................................................... 3-5
3-9. Zero Cal Softkey .......................................................................... 3-6
3-10. See Cal Dates Softkey.................................................................. 3-6
3-11. Cal Reports Softkey ..................................................................... 3-6
3-12. Update Cal Dates Menu ............................................................... 3-6
3-13. Periodic Calibration .............................................................................. 3-7
3-14. Calibrating the Main Input ............................................................... 3-7
3-15. Characterizing the DC Source...................................................... 3-7
3-16. DC Calibration ............................................................................. 3-13
3-17. AC Calibration ............................................................................. 3-19
3-18. Calibrating the Wideband AC Option .............................................. 3-27
3-19. Characterizing the AC Source...................................................... 3-29
3-20. Calibrating Wideband Input Gain at 1 kHz.................................. 3-31
3-21. Calibrating Wideband Input Flatness........................................... 3-33
3-22. Service Calibration ............................................................................... 3-35
3-23. Xfer Offset Adjustment .................................................................... 3-39
3-24. Wideband Amplifier Rolloff Adjustment......................................... 3-40
3-25. Verification ........................................................................................... 3-43
3-26. Verifying the Main Input (INPUT 1 or 2) ........................................ 3-43
3-27. Verifying AC-DC Difference for Regions I and III
(220 mV through 1000 V Range)................................................. 3-48

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3-28. Verifying Absolute AC Error for Region IV (70 mV through
700 mV Range) ............................................................................ 3-49
3-29. Verifying Absolute AC Error for Region II (2.2 V through
1000 V Range) ............................................................................. 3-52
3-30. Verifying Absolute AC Error for Region V (2.2 mV through
22 mV) ......................................................................................... 3-53
3-31. Verifying the Wideband AC Option................................................. 3-53
3-32. Wideband 1-kHz Gain VerificatioN, 7V, 2.2V, 700 mV, and
70 mV Ranges.............................................................................. 3-65
3-33. WIDEBAND 1-kHz GAIN VERIFICATION, 22 mV RANGE . 3-65
3-34. Wideband Gain Verification, 10 Hz to 500 kHz.......................... 3-66
3-35. Wideband Flatness Verification................................................... 3-66
4 Maintenance......................................................................................... 4-1
4-1. Introduction........................................................................................... 4-3
4-2. Cleaning the Air Filter .......................................................................... 4-3
4-3. General Cleaning .................................................................................. 4-3
4-4. Cleaning PCA's..................................................................................... 4-4
4-5. Access Procedures ................................................................................ 4-5
4-6. Top and Bottom Covers.................................................................... 4-5
4-7. Digital Section Cover ....................................................................... 4-5
4-8. Analog Section Covers..................................................................... 4-5
4-9. Rear Panel Removal and Installation................................................ 4-5
4-10. Rear Panel Assembly Access ........................................................... 4-6
4-11. Front Panel Removal and Installation .............................................. 4-7
4-12. Display Assembly Removal and Installation ............................... 4-7
4-13. Keyboard Assembly Removal and Installation............................ 4-7
4-14. Analog Assembly Removal and Installation .................................... 4-8
4-15. Digital Assembly Removal and Installation..................................... 4-8
4-16. Power Transformer Removal and Installation.................................. 4-8
4-17. Hybrid Cover Removal..................................................................... 4-9
4-18. Installing a Wideband AC Module (Option -03) .................................. 4-9
4-19. Clearing Ghost Images from the Control Display ................................ 4-10
4-20. Replacing the Clock/Calendar Backup Battery .................................... 4-11
4-21. Using Remote Commands Reserved for Servicing .............................. 4-11
4-22. Using the FATALITY? and FATALCLR Commands..................... 4-11
4-23. Error Codes........................................................................................... 4-12
5 Troubleshooting .................................................................................. 5-1
5-1. Introduction........................................................................................... 5-3
5-2. Main CPU (A20) Power-Up Tests ................................................... 5-3
5-3. A17 Guard Crossing Processor Power-Up Tests.............................. 5-3
5-4. System Startup Tests ........................................................................ 5-4
5-5. Diagnostic Tests ............................................................................... 5-4
5-6. Test Step: MAMA8255 (Motherboard 8255) .............................. 5-5
5-7. Test Step: DAC8254 (DAC 8254) ............................................... 5-6
5-8. Test Step: AD8255 (A/D 8255) ................................................... 5-6
5-9. Test Step: ADSELFTEST (A/D Internal Selftest) ....................... 5-7
5-10. Test Step: ADZEROS (A/D Zeros).............................................. 5-7
5-11. Test Step: ADNULLDAC (A/D Null DAC)................................ 5-7
5-12. Test Step: ADDAC (A/D DAC Output) ...................................... 5-8
5-13. Test Step: CHOPPER (A/D Chopper) ......................................... 5-9
5-14. Test Step: PROT (Protection) ...................................................... 5-10
5-15. Test Step: OVLD (Overload) ....................................................... 5-10

Contents (continued)
v
5-16. Test Step: ZEROS........................................................................ 5-11
5-17. Test Step: DIVIDERS (Input Dividers) ....................................... 5-11
5-18. Test Steps: X2_2V through X2_2MV.......................................... 5-12
5-19. Test Step: MATCH (Sensor Match) ............................................ 5-13
5-20. Test Step: XFREQ (Frequency Measuring) ................................. 5-13
5-21. Test Step: LOOPFILT (Sensor Filter).......................................... 5-13
5-22. Test Step: WOVLD (Wideband Overload).................................. 5-14
5-23. Test Steps: W7V through W2_2MV (Wideband 2.2 mV Range) 5-14
5-24. Test Step: WFREQ (Wideband Frequency Measuring)............... 5-14
5-25. Test Step: WLOOPFILT (Wideband Sensor Filter) .................... 5-15
6 List of Replacable Parts...................................................................... 6-1
6-1. Introduction........................................................................................... 6-3
6-2. How to Obtain Parts.............................................................................. 6-3
6-3. Manual Status Information ................................................................... 6-3
6-4. Newer Instruments................................................................................ 6-3
6-5. Service Centers ..................................................................................... 6-4
6-6. Parts Lists.............................................................................................. 6-4
7 Schematic Diagrams ........................................................................... 7-1
Appendices
A Glossary of AC-DC Transfer Related Terms .............................................. A-1
B ASCII and IEEE – 488 Bus Codes.............................................................. B-1
C Calibration Constant Information................................................................ C-1

5790A
Service Manual
vi

vii
List of Tables
Table Title Page
1-1. Symbols.................................................................................................................. 1-3
2-1. Analog Motherboard Connectors ........................................................................... 2-10
2-2. Supplies Generated by the Digital Power Supply .................................................. 2-12
2-3. CPU Acronym Glossary......................................................................................... 2-16
2-4. CPU Memory Map................................................................................................. 2-18
2-5. CPU Interrupts, Priorities, and Vectors.................................................................. 2-19
2-6. Front Panel Memory Map ...................................................................................... 2-22
2-7. Control Lines for the Keyboard LEDs ................................................................... 2-25
2-8. Unregulated Supplies from the Filter Assembly .................................................... 2-26
2-9. Regulated Supplies from the Filter Assembly........................................................ 2-27
2-10. Regulated Outputs from the Regulator/Guard Crossing Assembly ....................... 2-28
2-11. Inguard CPU Memory Map.................................................................................... 2-30
2-12. Inguard CPU Interrupts .......................................................................................... 2-32
3-1. Equipment Required for 5790A DC Characterization ........................................... 3-7
3-2. 5700A DC Characterization Test Record, Part 1 ................................................... 3-8
3-3. 5700A DC Characterization Test Record, Part 2 ................................................... 3-8
3-4. Equipment Required for 5790A Main Input DC Calibration................................. 3-13
3-5. Calibration Steps in Periodic Calibration............................................................... 3-16
3-6. Equipment Required for 5790A Main Input AC Calibration................................. 3-20
3-7. Equipment Required for Wideband Calibration..................................................... 3-28
3-8. Wideband Calibration Worksheet .......................................................................... 3-29
3-9. Attenuators Required for Each Range.................................................................... 3-34
3-10. Calibration Steps in Service Calibration ................................................................ 3-36
3-11. Wideband Amplifier Rolloff Adjustment Worksheet ............................................ 3-42
3-12. Main Input Verification Regions............................................................................ 3-43
3-13. Test Record for Main Input Verification................................................................ 3-44
3-14. Worksheet for Wideband 22 mV, 7 mV, and 2.2 mV 1 kHz Gain ........................ 3-55
3-15. Wideband Flatness Verification Worksheet........................................................... 3-55
3-16. Wideband Verification Test Record....................................................................... 3-56
6-1. Manual Status Information..................................................................................... 6-4
6-2. Final Assembly....................................................................................................... 6-5
6-2. A62 Input Block Assembly.................................................................................... 6-13
6-4. A1 Keyboard PCA ................................................................................................. 6-17
6-5. A2 Front Panel PCA............................................................................................... 6-19
6-6. A3 Analog Motherboard PCA................................................................................ 6-22

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6-7. A4 Digiital Motherboard PCA ............................................................................... 6-24
6-8. A6 Wideband PCA (Option -03)............................................................................ 6-27
6-9. A6A1 RMS Support PCA ...................................................................................... 6-32
6-10. A6A2 WB Input Protection PCA ........................................................................... 6-35
6-11. A10 Transfer PCA.................................................................................................. 6-37
6-12. A10A1 Precision Amplifier PCA........................................................................... 6-42
6-13. A10A2 HV Protection PCA ................................................................................... 6-44
6-14. A10A3 High-Gain Precision Amplifier PCA......................................................... 6-46
6-15. A15 A/D Amplifier PCA........................................................................................ 6-48
6-16. A16 DAC PCA....................................................................................................... 6-52
6-17. A16A1 DAC Filter PCA ........................................................................................ 6-56
6-18. A17 Regulator/Guard Crossing PCA ..................................................................... 6-58
6-19. A18 Filter PCA ...................................................................................................... 6-62
6-20. A19 Digital Power Supply PCA............................................................................. 6-65
6-21. A20 CPU PCA ....................................................................................................... 6-69
6-22. A21 Rear Panel I/O PCA ....................................................................................... 6-72

ix
List of Figures
Figure Title Page
1-1. Dimensions............................................................................................................. 1-18
2-1. Functional Block Diagram ..................................................................................... 2-7
2-2. Digital Section Block Diagram .............................................................................. 2-8
2-3. RS-232 Connector Pinout....................................................................................... 2-11
2-4. CPU Assembly Block Diagram.............................................................................. 2-15
2-5. A10 Transfer Assembly Block Diagram................................................................ 2-33
2-6. Divider Network Simplified Schematic ................................................................. 2-34
2-7. Chopper Circuit Block Diagram ............................................................................ 2-37
2-8. A15 A/D Amplifier Block Diagram....................................................................... 2-39
2-9. A16 DAC Assembly Block Diagram ..................................................................... 2-42
2-10. A6 Wideband Assembly Block Diagram ............................................................... 2-46
3-1. 5790A Calibration Memory Organization ............................................................. 3-4
3-2. DC Source Characterization Setup, Part 1 ............................................................. 3-9
3-3. DC Source Characterization Setup, Part 2 ............................................................. 3-10
3-4. DC Source Characterization Setup, Part 3 ............................................................. 3-11
3-5. 5790A DC Calibration Test Setup ......................................................................... 3-14
3-6. Worksheet for 2 V to 1000 V AC Calibration Points............................................. 3-20
3-7. Worksheet for 60 mV to 600 mV AC Calibration Points ...................................... 3-21
3-8. 5790A AC Calibration Test Setup ......................................................................... 3-22
3-9. Millivolt Range Bootstrapping Technique............................................................. 3-26
3-10. Wideband Calibration Source Characterization, Part 1.......................................... 3-30
3-11. Wideband Calibration Source Characterization, Part 2.......................................... 3-31
3-12. Gain Calibration Setup for 70 mV and Above....................................................... 3-32
3-13. WIDEBAND Input Flatness Calibration Test Setup.............................................. 3-33
3-14. Location of R27 (Transfer), and C20 and C24 (Wideband)................................... 3-41
3-15. Worksheet for AC-DC Error, 70 mV through 700 mV Ranges............................. 3-50
3-16. Worksheet for AC-DC Error, All Other Ranges .................................................... 3-51
3-17. Worksheet for Absolute AC Error, 70 mV through 700 mV Ranges .................... 3-52
3-18. Worksheet for DC Error, 2.2 V through 1000 V Ranges ....................................... 3-54
3-19. Wideband Verification Test Setup, Part 2.............................................................. 3-66
4-1. Accessing the Air Filter.......................................................................................... 4-4
4-2. Rear Panel Removal............................................................................................... 4-5
4-3. Rear Panel Assembly Access ................................................................................. 4-6
4-4. Front Panel Removal.............................................................................................. 4-7
4-5. Analog and Digital Assemblies.............................................................................. 4-10

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6-1. Final Assembly....................................................................................................... 6-8
6-1. Final Assembly (cont) ............................................................................................ 6-13
6-2. A62 Input Block Assembly.................................................................................... 6-16
6-3. A1 Keyboard PCA ................................................................................................. 6-18
6-4. A2 Front Panel PCA............................................................................................... 6-21
6-5. A3 Analog Motherboard PCA................................................................................ 6-23
6-6. A4 Digital Motherboard PCA ................................................................................ 6-26
6-7. A6 Wideband PCA (Option -03)............................................................................ 6-31
6-8. A6A1 RMS Support PCA ...................................................................................... 6-34
6-9. A6A2 WB Input Protection PCA ........................................................................... 6-36
6-10. A10 Transfer PCA.................................................................................................. 6-41
6-11. A10A1 Precision Amplifier PCA........................................................................... 6-43
6-12. A10A2 High Voltage Protection Amplifier PCA................................................... 6-45
6-13. A10A3 High-Gain Precision Amplifier PCA......................................................... 6-47
6-14. A15 A/D Amplifier PCA........................................................................................ 6-51
6-15. A16 DAC PAC....................................................................................................... 6-55
6-16. A16A1 DAC Filter PCA ........................................................................................ 6-57
6-17. A17 Regulatorr/Guard Crossing PCA.................................................................... 6-61
6-18. A18 Filter PCA ...................................................................................................... 6-64
6-19. A19 Digital Power Supply PCA............................................................................. 6-68
6-20. A20 CPU PCA ....................................................................................................... 6-71
6-21. A21 Rear Panel I/O PCA ....................................................................................... 6-74

1-1
Chapter 1
Introduction and Specifications
Title Page
1-1. Introduction........................................................................................... 1-3
1-2. Service Information .............................................................................. 1-3
1-3. Symbols ................................................................................................ 1-3
1-4. Safety Instructions ................................................................................ 1-4
1-5. Input Source Limits .......................................................................... 1-4
1-6. Power Source.................................................................................... 1-4
1-7. Proper Fuse Usage............................................................................ 1-4
1-8. Grounding of the 5790A................................................................... 1-4
1-9. Proper Power Cord Usage ................................................................ 1-4
1-10. Do Not Operate in Explosive Atmosphere....................................... 1-4
1-11. Do Not Attempt to Operate if Protection may be Impaired.............. 1-4
1-12. Do Not Remove the Cover unless Qualified .................................... 1-5
1-13. Do Not Service Alone ...................................................................... 1-5
1-14. Use Care when Servicing with Power On ........................................ 1-5
1-15. Specifications........................................................................................ 1-5

5790A
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1-2

Introduction and Specifications
Introduction 1
1-3
1-1. Introduction
The 5790A makes AC-DC transfer measurements and accurate AC measurements from
700 μV to 1000 V (10 Hz to 1 MHz). The optional 5790A-03 Wideband Module
increases the 5790A frequency range to 30 MHz for inputs connected to the
WIDEBAND 50 eType “N” connector. Accessory 5790A-7001 allows the use of Fluke
A40 or A40A Current Shunts with 5790A for making accurate AC-DC current transfer
measurements up to 20 A.
Refer to the 5790A Operator Manual for operating instructions, use of the front and rear
panel features, remote programming, and all other information for the operator.
This service manual is a maintenance guide for the 5790A. The following topics are
included:
•Theory of operation
•Calibration
•Performance testing
•Access procedures
•Troubleshooting
•Parts lists
•Schematic diagrams
1-2. Service Information
Factory authorized service for 5790A is available at selected Service Centers. For
warranty or after-warranty service, contact the nearest Service Center for instructions. A
complete list of Service Centers appears at the end of Chapter 6.
To reship the 5790A, use its original shipping carton. If the original carton is not
available, use a container that provides adequate protection during shipment. Protect the
5790A with at least three inches of shock-absorbing material on all sides of the container.
Do not use loose fill to pad the shipping container. Loose fill allows the instrument to
settle to one corner of the shipping container, which could result in damage during
shipment.
1-3. Symbols
Table 1-1 lists the symbols used on the instrument and/or in this manual.
Table 1-1. Symbols
Symbol Description
XHazardous voltage.
| Power On.
OPower Off.
JEarth ground.
WImportant information. See manual.

5790A
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1-4
1-4. Safety Instructions
Please read this chapter carefully. It will familiarize you with important safety
instructions for handling your 5790A instrument. In this manual a Warning identifies
conditions and actions that pose hazard(s) to the user. A Caution identifies conditions
and actions that may damage the test instrument
The instrument is designed and tested in accordance with IEC Publication 348, Safety
Requirements for Electronics Measuring Apparatus 5790A. If the instrument is used
improperly, there is risk damage to persons and property.
1-5. Input Source Limits
To avoid electrical shock or fire, connect the input terminals only to sources that do not
exceed 1000 V RMS or DC, and that cannot exceed 200 mA operational or short circuit
current.
1-6. Power Source
The 5790A is intended to operate from a power source that will not apply more than
264 V AC RMS between the supply conductors or between the supply conductor and
ground. A protective ground connection through the grounding conductor in the power
cord is essential for safe operation.
1-7. Proper Fuse Usage
To avoid fire hazard, use only a fuse identical in type, voltage rating and current rating as
specified on the rear panel fuse rating label. Do not use makeshift fuses or short circuit
the fuse holder.
1-8. Grounding of the 5790A
The 5790A instrument is a Safety Class I (grounded enclosure) instrument as defined in
IEC 348. The enclosure is grounded through the grounding conductor of the power cord.
To avoid electrical shock, plug the power cord into a properly wired earth grounded
receptacle before connecting anything to any of the binding posts, terminals or
connectors. A protective ground connection by way of the grounding conductor in the
power cord is essential for safe operation.
1-9. Proper Power Cord Usage
•Use only the power cord and connector appropriate for the voltage and plug
configuration in your country.
•Use only a power cord that is in good condition.
•Refer cord and connector changes to qualified service personnel.
1-10. Do Not Operate in Explosive Atmosphere
To avoid explosion, do not operate the 5790A in an atmosphere of explosive gas.
1-11. Do Not Attempt to Operate if Protection may be Impaired
If the 5790A appears damaged or operates abnormally, protection may be impaired. Do
not attempt to operate it. When in doubt, have the instrument serviced.

Introduction and Specifications
Specifications 1
1-5
1-12.
Do Not Remove the Cover unless Qualified
To avoid electric shock, do not remove the 5790A cover unless you are qualified to do so.
Service procedures are for qualified service personnel only.
1-13. Do Not Service Alone
Do not perform internal service or adjustment of this product unless a person capable of
rendering first aid resuscitation is present.
1-14. Use Care when Servicing with Power On
Dangerous voltages exist at several points inside this product. To avoid personal injury,
do not touch exposed connections and components while the power is on.
1-15.Specifications
Specifications are valid after allowing a warm-up period of 30 minutes, or twice the time
the 5790A has been turned off, whichever is less. For example, if the 5790A has been
turned off for 5 minutes, the warm-up period is 10 minutes.
To simplify the evaluation of how 5790A covers you workload, use the Absolute
Uncertainty Specification. Those include stability, temperature coefficient, linearity, and
traceability to external standards.
Note
When you use the 5790A within
± 5 ° C of the temperature of the last
calibration, you do not need to add anything to the Absolute Uncertainty
Specifications to determine the ratios between 5790A uncertainties and the
uncertainties of a unit under test. The initial calibration at Fluke is done at
23
° C. (You can verify the temperature of the last calibration at any time by
pressing the [SPEC] key.)
Use the Relative Uncertainty Specifications if you use a different procedure to calibrate
the 5790A than is specified in the 5790A Service Manual. To calculate absolute
uncertainty specifications under such conditions, combine the absolute uncertainty
associated with your external equipment and calibration procedures with the Relative
Uncertainty Specifications.
Secondary Performance and Operating Characteristics are provided for special calibration
requirements such as stability or operation at temperature extremes.

5790A
Service Manual
1-6
Absolute Uncertainty Specifications
±5 °C of Calibration Temperature
Absolute Uncertainty
Measurement Mode
±(ppm of Reading + μV)
Voltage Range Frequency Range AC/DC Transfer
Mode ±ppm
2 Years 90 Days 1 Year 2 Years
2.2 mV
10 Hz - 20 Hz
20 Hz- 40 Hz
40 Hz - 20 kHz
20 kHz - 50 kHz
50 kHz - 100 kHz
100 kHz - 300 kHz
300 kHz - 500 kHz
500 kHz - 1 MHz
1700 + 1.3
740 + 1.3
420 + 1.3
810 + 2.0
1200 + 2.5
2300 + 4.0
2400 + 6.0
3200 + 6.0
1700 + 1.3
740 + 1.3
420 + 1.3
810 + 2.0
1200 + 2.5
2300 + 4.0
2400 + 8.0
3500 + 8.0
1700 + 1.3
740 + 1.3
420 + 1.3
820 + 2.0
1200 + 2.5
2300 + 4.0
2600 + 8.0
5000 + 8.0
7 mV
10 Hz - 20 Hz
20 Hz - 40 Hz
40 Hz - 20 kHz
20 kHz - 50 kHz
50 kHz - 100 kHz
100 kHz - 300 kHz
300 kHz - 500 kHz
500 kHz - 1 MHz
850 + 1.3
370 + 1.3
210 + 1.3
400 + 2.0
600 + 2.5
1200 + 4.0
1300 + 6.0
2000 + 6.0
850 + 1.3
370 + 1.3
210 + 1.3
400 + 2.0
600 + 2.5
1200 + 4.0
1300 + 8.0
2300 + 8.0
850 + 1.3
370 + 1.3
210 + 1.3
410 + 2.0
610 + 2.5
1200 + 4.0
1400 + 8.0
3600 + 8.0
22 mV
10 Hz - 20 Hz
20 Hz - 40 Hz
40 Hz - 20 kHz
20 kHz - 50 kHz
50 kHz - 100 kHz
100 kHz - 300 kHz
300 kHz - 500 kHz
500 kHz - 1 MHz
290 + 1.3
180 + 1.3
110 + 1.3
210 + 2.0
310 + 2.5
810 + 4.0
860 + 6.0
1400 + 6.0
290 + 1.3
190 + 1.3
110 + 1.3
210 + 2.0
310 + 2.5
810 + 4.0
890 + 8.0
1700 + 8.0
290 + 1.3
190 + 1.3
110 + 1.3
210 + 2.0
310 + 2.5
820 + 4.0
1000 + 8.0
2600 + 8.0
70 mV
10 Hz - 20 Hz[1]
20 Hz - 40 Hz
40 Hz - 20 kHz
20 kHz - 50 kHz
50 kHz - 100 kHz
100 kHz - 300 kHz
300 kHz - 500 kHz
500 kHz - 1 MHz
240 + 1.5
120 + 1.5
64 + 1.5
120 + 2.0
260 + 2.5
510 + 4.0
660 + 6.0
1100 + 6.0
240 + 1.5
120 + 1.5
65 + 1.5
130 + 2.0
260 + 2.5
510 + 4.0
670 + 8.0
1100 + 8.0
240 + 1.5
130 + 1.5
69 + 1.5
130 + 2.0
260 + 2.5
530 + 4.0
680 + 8.0
1300 + 8.0
210
82
34
67
220 mV
10 Hz - 20 Hz[1]
20 Hz - 40 Hz
40 Hz - 20 kHz
20 kHz - 50 kHz
50 kHz - 100 kHz
100 kHz - 300 kHz
300 kHz - 500 kHz
500 kHz - 1 MHz
210 + 1.5
84 + 1.5
37 + 1.5
69 + 2.0
160 + 2.5
240 + 4.0
360 + 6.0
940 + 6.0
210 + 1.5
85 + 1.5
38 + 1.5
69 + 2.0
160 + 2.5
250 + 4.0
380 + 8.0
1000 + 8.0
210 + 1.5
87 + 1.5
43 + 1.5
73 + 2.0
160 + 2.5
280 + 4.0
400 + 8.0
1200 + 8.0
210
73
27
47
700 mV
10 Hz - 20 Hz[1]
20 Hz - 40 Hz
40 Hz - 20 kHz
20 kHz - 50 kHz
50 kHz - 100 kHz
100 kHz - 300 kHz
300 kHz - 500 kHz
500 kHz - 1 MHz
210 + 1.5
75 + 1.5
31 + 1.5
50 + 2.0
79 + 2.5
160 + 4.0
300 + 6.0
900 + 6.0
210 + 1.5
76 + 1.5
33 + 1.5
51 + 2.0
79 + 2.5
180 + 4.0
300 + 8.0
960 + 8.0
210 + 1.5
78 + 1.5
38 + 1.5
56 + 2.0
84 + 2.5
210 + 4.0
340 + 8.0
1200 + 8.0
[1] For 9.5 to 10 Hz, the specifications is ±(1000 ppm of reading + 1.5 μV)

Introduction and Specifications
Specifications 1
1-7
Absolute Uncertainty Specifications (cont.)
±5 °C of Calibration Temperature
Absolute Uncertainty
Measurement Mode
±(ppm of Reading)
Voltage
Range Frequency Range AC/DC Transfer
Mode ±ppm
2 Years 90 Days 1 Year 2 Years
10 Hz - 20 Hz[2] 200 200 200 200
20 Hz - 40 Hz 63 65 66 69
40 Hz - 20 kHz 18 22 24 29
20 kHz - 50 kHz 43 45 46 52
50 kHz - 100 kHz 70 71 76
100 kHz - 300 kHz 150 160 200
300 kHz - 500 kHz 250 260 310
2.2 V
500 kHz - 1 MHz 840 900 1200
10 Hz - 20 Hz[2] 200 200 200 200
20 Hz - 40 Hz 63 66 67 70
40 Hz - 20 kHz 18 22 24 29
20 kHz - 50 kHz 44 46 48 53
50 kHz - 100 kHz 80 81 88
100 kHz - 300 kHz 180 190 220
300 kHz - 500 kHz 380 400 470
7 V
500 kHz - 1 MHz 1100 1200 1500
10 Hz - 20 Hz[2] 200 200 200 200
20 Hz - 40 Hz 63 66 67 70
40 Hz - 20 kHz 21 25 27 31
20 kHz - 50 kHz 44 46 48 53
50 kHz - 100 kHz 80 81 85
100 kHz - 300 kHz 180 190 220
300 kHz - 500 kHz 380 400 470
22 V
500 kHz - 1 MHz 1100 1200 1500
10 Hz - 20 Hz[2] 200 200 200 200
20 Hz - 40 Hz 63 67 68 72
40 Hz - 20 kHz 25 30 32 39
20 kHz - 50 kHz 55 56 57 63
50 kHz - 100 kHz 91 94 110
100 kHz - 300 kHz 190 200 220
300 kHz - 500 kHz 400 410 510
70 V
500 kHz - 1 MHz 1100 1200 1500
10 Hz - 20 Hz 200 200 200 200
20 Hz - 40 Hz 63 67 68 72
40 Hz - 20 kHz 23 29 31 38
20 kHz - 50 kHz 63 67 69 77
50 kHz - 100 kHz 96 98 110
100 kHz - 300 kHz 210 210 260
220 V
300 kHz - 500 kHz 440 500 700
10 Hz - 20 Hz 200 200 200 200
20 Hz - 40 Hz 92 96 99 110
40 Hz - 20 kHz 36 39 41 47
20 kHz - 50 kHz 120 130 150
700 V
50 kHz - 100 kHz 400 500 850
10 Hz - 20 Hz 200 200 200 200
20 Hz - 40 Hz 92 96 99 110
40 Hz - 20 kHz 33 37 38 44
20 kHz - 50 kHz 120 130 150
1000 V
50 kHz - 100 kHz 400 500 850
[2] For 9.5 to 10 Hz, the specifications is ±(1000 ppm of reading)

5790A
Service Manual
1-8
Relative Uncertainty Specifications
±5 °C of Calibration Temperature
Relative Uncertainty
Measurement Mode
±(ppm of Reading + μV)
Voltage Range Frequency Range AC/DC Transfer
Mode ±ppm
2 Years 90 Days 1 Year 2 Years
10 Hz - 20 Hz 100 + 1.3 110 + 1.3 110 + 1.3
20 Hz - 40 Hz 54 + 1.3 64 + 1.3 68 + 1.3
40 Hz - 20 kHz 44 + 1.3 57 + 1.3 61 + 1.3
20 kHz - 50 kHz 57 + 2.0 67 + 2.0 110 + 2.0
50 kHz - 100 kHz 79 + 2.5 86 + 2.5 120 + 2.5
100 kHz - 300 kHz 190 + 4.0 230 + 4.0 390 + 4.0
300 kHz - 500 kHz 590 + 6.0 720 + 8.0 1200 + 8.0
2.2 mV
500 kHz - 1 MHz 2200 + 6.0 2600 + 8.0 4400 + 8.0
10 Hz - 20 Hz 80 + 1.3 83 + 1.3 86 + 1.3
20 Hz - 40 Hz 33 + 1.3 39 + 1.3 45 + 1.3
40 Hz - 20 kHz 29 + 1.3 36 + 1.3 42 + 1.3
20 kHz - 50 kHz 40 + 2.0 4 + 2.0 63 + 2.0
50 kHz - 100 kHz 53 + 2.5 57 + 2.5 72 + 2.5
100 kHz - 300 kHz 110 + 4.0 130 + 4.0 210 + 4.0
300 kHz - 500 kHz 370 + 6.0 450 + 8.0 740 + 8.0
7 mV
500 kHz - 1 MHz 1600 + 6.0 2000 + 8.0 3400 + 8.0
10 Hz - 20 Hz 69 + 1.3 72 + 1.3 75 + 1.3
20 Hz - 40 Hz 34 + 1.3 40 + 1.3 46 + 1.3
40 Hz - 20 kHz 30 + 1.3 36 + 1.3 43 + 1.3
20 kHz - 50 kHz 40 + 2.0 45 + 2.0 64 + 2.0
50 kHz - 100 kHz 53 + 2.5 57 + 2.5 73 + 2.5
100 kHz - 300 kHz 97 + 4.0 110 + 4.0 160 + 4.0
300 kHz - 500 kHz 310 + 6.0 380 + 8.0 610 + 8.0
22 mV
500 kHz - 1 MHz 1200 + 6.0 1500 + 8.0 2500 + 8.0
10 Hz - 20 Hz 60 + 1.5 61 + 1.5 62 + 1.5
20 Hz - 40 Hz 27 + 1.5 30 + 1.5 37 + 1.5
40 Hz - 20 kHz 22 + 1.5 25 + 1.5 34 + 1.5
20 kHz - 50 kHz 34 + 2.0 36 + 2.0 44 + 2.0
50 kHz - 100 kHz 53 + 2.5 54 + 2.5 62 + 2.5
100 kHz - 300 kHz 110 + 4.0 120 + 4.0 170 + 4.0
300 kHz - 500 kHz 270 + 6.0 290 + 8.0 320 + 8.0
70 mV
500 kHz - 1 MHz 910 + 6.0 970 + 8.0 1200 + 8.0
10 Hz - 20 Hz 55 60 + 1.5 61 + 1.5 62 + 1.5
20 Hz - 40 Hz 20 27 + 1.5 29 + 1.5 35 + 1.5
40 Hz - 20 kHz 17 22 + 1.5 24 + 1.5 31 + 1.5
20 kHz - 50 kHz 17 22 + 2.0 24 + 2.0 33 + 2.0
50 kHz - 100 kHz 51 + 2.5 52 + 2.5 59 + 2.5
100 kHz - 300 kHz 100 + 4.0 120 + 4.0 170 + 4.0
300 kHz - 500 kHz 260 + 6.0 290 + 8.0 310 + 8.0
220 mV
500 kHz - 1 MHz 890 + 6.0 950 + 8.0 1200 + 8.0
10 Hz - 20 Hz 55 60 + 1.5 61 + 1.5 62 + 1.5
20 Hz - 40 Hz 20 27 + 1.5 29 + 1.5 34 + 1.5
40 Hz - 20 kHz 15 22 + 1.5 24 + 1.5 31 + 1.5
20 kHz - 50 kHz 15 22 + 2.0 24 + 2.0 33 + 2.0
50 kHz - 100 kHz 51 + 2.5 52 + 2.5 59 + 2.5
100 kHz - 300 kHz 100 + 4.0 120 + 4.0 170 + 4.0
300 kHz - 500 kHz 260 + 6.0 270 + 8.0 310 + 8.0
700 mV
500 kHz - 1 MHz 890 + 6.0 950 + 8.0 1200 + 8.0