Agilent 6681A - Manuals

5 Table of Contents Introduction ............................................................................................................................................................................ 7 Scope..........................................................................................

Introduction 7 1 Introduction Scope Organization This manual contains information for troubleshooting and repairing to the component level Agilent Series 668xA,5-kilowatt power supplies. The remaining chapters of this manual are organized as follows: Chapter Description Chapter 2 Verification proced...

Introduction 8 Related Documents Change Sheet There may or may not be a Manual Change sheet included with this manual (see Manual Revisions). If one is included, be sure to examine it for changes to this manual. Operating Manual Each power supply is shipped with an operating manual (see Replaceable ...

Introduction 9 Safety Considerations This power supply is a Safety Class I instrument, which means it has a protective earth terminal. This terminal must beconnected to earth ground through a power source equipped with a 4-wire, ground receptacle. Refer to the "SafetySummary" page at the beg...

Verification 11 2 Verification Introduction This chapter provides test procedures for checking the operation of Agilent Series 668xA power supplies. The required testequipment is specified and sample performance test record sheets are included. Instructions are given for performing thetests either f...

12 Verification Table 2-1. Test Equipment Required Type Required Characteristics Recommended Model Digital Voltmeter 1 Resolution: 10 nV @ 1V Agilent 3458A Readout: 8 1/2 digits Accuracy: 20 ppm Current Monitor Resistor 1 Agilent 6682A, 6683A, Agilent 6684A: Guildline 9230/300 0.001 Ω ± 0.04%, 300A,...

Verification 13 Programming The Tests General Considerations Procedures are given for programming these tests either from the front panel keypad or from a GPIB controller. Theprocedures assume you know how to use the front panel keypad or how to program over the GPIB (see the Power SupplyOperating M...

14 Verification Operation Verification Tests Table 2-3 lists the requirements for operation verification, which is a subset of the performance tests. Table 2-3. Operation Verification Tests Test Refer To 1 Turn-On Checkout Power Supply Operating Manual 2 Voltage Programming and Readback Accuracy Tab...

Verification 15 Figure 2-1. Constant Voltage (CV) Test Setup

Verification 17 Table 2-4. Constant Voltage (CV) Tests (continued) Action Normal Result CV Source Effect (cont) 2 Set the transformer to the nominal ac line voltage. Connect the DVMacross +S and -S (see Fig. 2-1). 3 Turn on the power supply and program the current to its maximumprogrammable value an...

Verification 19 Constant Current (CC) Tests Test Setup Connect the appropriate current monitoring resistor (see Table 2-l) as shown in Fig. 2-3. The accuracy of the resistor mustbe as specified in the table. Test Procedures The test procedures are given in Table 2-5. The tests are independent and ma...

20 Verification Table 2-5. Constant Current (CC) Tests (continued) Action Normal Result CC Noise (PARD) (cont) 2 Measure the residual noise on the DVM with the power supply turned off.Noise generated by other equipment may affect this measurement andshould be removed or factored out. 3 Turn on the p...

Verification 21 Table 2-5. Constant Current (CC) Tests (continued) Action Normal Result CC Source Effect This test measures the change in output current resulting from a change in ac line voltage from its minimum to itsmaximum value within the line voltage specifications. It is recommended that you ...

22 Verification Figure 2-3. CC Load Effect Test Setup

Verification 23 Figure 2-4. CC rms Noise Test Setup

24 Verification Averaging the CC Measurements The CC Load Effect and CC Source Effect tests measure the dc regulation of the power supply's output current. Whendoing these tests, you must be sure that the readings taken are truly dc regulation values and not instantaneous ac peaks ofthe output curre...

Verification 25 Table 2-6. Performance Test Record Form Test Facility : __________________________________________ Report No.__________________________________________ __________________________________________ Date______________________________________________ ______________________________________...

Troubleshooting 31 3 Troubleshooting Shock Hazard : Most of the procedures in this chapter must be performed with power applied and protective covers removed. These procedures should be done only by trained service personnel aware of the hazard from electrical shock. This instrument uses components ...

32 Troubleshooting Test Equipment Required Table 3-1. Test Equipment Required Equipment Purpose Recommended Model Logic Probe To check states of data lines. Agilent 545A Test Clips To gain access to IC pins. AP Products No. LTC Ammeter/Current Shunt To measure output current. Agilent 6680A & 668...

34 Troubleshooting Troubleshooting Charts Figure 3-1 gives overall troubleshooting procedures to isolate the fault to a circuit board or particular circuit (see Figure3-20 for the location of the circuit boards). These procedures include the use of power-on selftest (Table 3-2) and signatureanalysis...

Troubleshooting 35 Figure 3-1. Overall Troubleshooting (Sheet 1 of 4)

36 Troubleshooting Figure 3-1. Overall Troubleshooting (Sheet 2 of 4)

Troubleshooting 37 Figure 3-1. Overall Troubleshooting (Sheet 3 of 4)

38 Troubleshooting Figure 3-1. Overall Troubleshooting (Sheet 4 of 4)

Troubleshooting 39 Figure 3-2. No Display Troubleshooting

Troubleshooting 41 Figure 3-4. OV At Turn-On Troubleshooting

42 Troubleshooting Figure 3-5. Output Held Low Troubleshooting (Sheet 1 of 2)

Troubleshooting 43 Figure 3-5. Output Held Low Troubleshooting (Sheet 2 of 2)

Troubleshooting 47 Figure 3-9. CV/CC DAC and Amplifier Circuit Troubleshooting

48 Troubleshooting Figure 3-10. Serial Down Troubleshooting (Sheet 1 of 2)

Troubleshooting 49 Figure 3-10. Serial Down Troubleshooting (Sheet 2 of 2)

50 Troubleshooting Figure 3-11. Secondary Interface Down (Sheet 1 of 2)

Troubleshooting 51 Figure 3-11. Secondary Interface Down (Sheet 2 of 2)

Troubleshooting 53 CV/CC Status Annunciators Troubleshooting When troubleshooting the CV/CC status annunciators or status readback circuits, first measure the voltage drop across thegating diodes, which are Al0D651 for the CC circuit and Al0D652 for the CV circuit (see A10, Sheet 2). A conductingdio...

56 Troubleshooting Signature Analysis Introduction The easiest and most efficient method of troubleshooting microprocessor-based instruments is with signature analysis (SA).This technique is similar to signal tracing with an oscilloscope in linear circuits. Part of the microprocessor memory isdedica...

Troubleshooting 57 Test Headers The power supply has two test headers as shown in Figure 3-15, each with a jumper that can be moved to differentpositions for SA testing and for other functions. To gain access to the headers, remove the power supply top cover. Pins Description Primary Interface Test ...

58 Troubleshooting Table 3-5. Primary Interface SA Test Description : These signatures check some primary interface circuits on the Systems Supply A2 GPIB Board. Valid A2U106 ROM Firmware Revision: A.01.06 Test Setup: See Figure 3-17. 1. Turn off the power supply and remove the top cover. 2. Connect...

Troubleshooting 59 Figure 3-16. Signature Analysis Connections, (Sheet 1 of 2)

60 Troubleshooting Figure 3-16. Signature Analysis Connections, (Sheet 2 of 2) Table 3-6. Front Panel SA Test Description : These signatures check front panel microprocessor AlU3. Valid A1U4 ROM Firmware Revision: A.01.07 Test Setup: See Figure 3-17. 1 .Turn off the power supply and remove the top c...

Troubleshooting 61 Table 3-7. Secondary Interface SA Test Description : These signatures check the secondary microprocessor A5U504. Valid A5U504 ROM Firmware Revision: A.01.04 Test Setup: See Figure 3-17. 1. Turn off the power supply and remove the top cover. 2. To obtain a setup that allows access ...

Troubleshooting 63 EEPROM Initialization EEPROM AlU6 on the A1 Front Panel Board stores the supply's GPIB address, model number, and constants required toprogram and calibrate the power supply. If either the front panel board or the EEPROM is replaced, the power supply mustbe reinitialized with the ...

64 Troubleshooting 10 ! Program to initialize EPROM or move factory preset data in 668xA 20 ! power supplies. 30 ! RE-STORE " INIT_668X" 40 ! Rev A.00.00 dated 09 Nov 1993 50 ! 60 DIM Init_data(1:49),Model$[5],Idn$[21],Cal_data$[40] 70 INTEGER Addr(1:49),Length(1:49) 80 ASSIGN @Ps TO 705 ! S...

Troubleshooting 65 510 DATA 115,30,20,1,127,.002701,.2,.00042,10.25 520 ! 530 Eprom_data_6684: ! ! EEPROM data for 6684A 540 DATA 93,74,41,0,83,0,29,70,131,0 550 DATA 98,21,4.6,10,50,0,83,255,20,10 560 DATA 6684,87,97,28,93,128,5,255,0,0 570 DATA 1296,6684,0,20,180,20,180,175,33,98 580 DATA 115,30,2...

66 Troubleshooting 1020 GOSUB Ps_error ! Error if passcode is not "0"! 1030 IF Err THEN 1040 OUTPUT @Ps;"*IDN?" ! Get data from model # location 1050 ENTER @Ps;Idn$ 1060 Model=VAL(Idn$[POS(Idn$,”,”)+1] ) 1070 ELSE 1080 GOTO Start 1090 END IF 1100 ! 1110 OUTPUT @Ps;"CAL:STATE ON,&...

Troubleshooting 67 1530 CLEAR SCREEN 1540 PRINT "This program should ONLY be completed if your power supply” 1550 PRINT "EEPROM has been replaced or a component that will effect" 1560 PRINT "the calibration AND the alignment of voltage, overvoltage" 1570 PRINT "and current is...

68 Troubleshooting 2010 IF Err THEN 2020 PRINT "An error occurred during the EEPROM read/write, Check for" 2030 PRINT "programming errors. Initialization data may be incorrect." 2040 STOP 2050 END IF 2060 ! 2070 PRINT "Operation complete. Program stopped." 2080 STOP 2090 ! 21...

Troubleshooting 69 Top Cover 1. Remove the four screws that secure the carrying straps (two TORX 20 screws on each side). These same screws securethe cover to the chassis. 2. Spread the bottom rear of the cover, and then pull the cover backwards towards the rear of the power supply todisengage it fr...

70 Troubleshooting A4 AC Input Assembly To remove the A4 AC Input Board first remove the GPIB board then disconnect these cables from the following connectorsat the GPIB board: 1. Disconnect the cables going to connector J417 and J420. 2. Disconnect the cable going to connector J419. 3. Remove the t...

Troubleshooting 71 A10 Control Assembly Disconnect the cables from the following connectors at the A10 DC RAIL board: 1. Disconnect the ribbon cable going from to the A6 Bias board. This cable connects to J509 on the A10 board but it iseasier to disconnect it at the A6 Bias Board. 2. Disconnect cabl...

72 Troubleshooting A1DSP1 LCD Display 1. Remove the A1 Front Panel Board as described in that procedure. 2. Remove the nuts securing the LCD display to the front panel assembly and remove the LCD and attached ribbon cable(see CAUTION below). (When reinstalling this cable, be sure to line up the cabl...

Troubleshooting 73 Figure 3-18. Component Locations (Top Cover and RFI Shield Removed)

74 Troubleshooting Figure 3-19. 5-Inch Front Panel Frame Assembly

Troubleshooting 75 Figure 3-20. 3-Inch Front Panel Frame Assembly

76 Troubleshooting Figure 3-21. Assembly A10, Exploded View

Troubleshooting 77 Figure 3-22. Assembly A10, Exploded View (6680A, 6681A)

78 Troubleshooting Figure 3-23. Assembly A10, Exploded View (6682A, 6683A, 6684A)

Troubleshooting 79 Figure 3-24. Three-Phase Line Choke Subchassis Wiring

80 Troubleshooting Figure 3-25. 24 Volt Fan Transformer

Principles Of Operation 81 4 Principles Of Operation Introduction Figure 4-3 (at the end of this chapter) is a block diagram showing the major circuits within the power supply. The powersupply consists of the following circuits: • A1 Front Panel Board ckts. • A2 GPIB ckts. • A10 Control Board includ...

82 Principles Of Operation A digital control interface on the A2 GPIB Board provides the following power supply functions: • Relay link. • Digital 1/0. • Remote inhibit (INH). • Discrete fault indicator (FLT). An optical isolator IC (U113) isolates the FLT output signal common from the external faul...

Principles Of Operation 83 The Secondary Microprocessor translates serial data received from the A2 board into parallel 12 bit data. The data bus isconnected directly to the four DAC/OpAmp circuits. Under control of the lip the selected DAC converts the bus data intoan analog signal. The DAC referen...

84 Principles Of Operation any value of load impedance. Switching between CV and CC is done automatically by the CV/CC control circuits at avalue of load impedance equal to the ratio of the programmed voltage value to the programmed current value. A low-level CV or CC signal is generated by the appl...

Principles Of Operation 85 A4 AC Input Board The A4 Input Board contains the Inrush-Current Limit relay (K401), Main Power Relay (K402), current-limiting resistors(R407, R408) and open-fuse-detect resistor circuit (R400-R405). On power-on, the current-limit relay (K401) closesallowing the dc rail ca...

86 Principles Of Operation Figure 4-2. 1ST Stage of the FET H-Bridge Configuration Output Circuits The output circuits include the following circuits: • Chassis mounted components. • Two power transformers, T900/T901. • Two inductors, L900/L901. • Four rectifiers, D900 through D903. • Output capacit...

Replaceable Parts 89 5 Replaceable Parts INTRODUCTION Chapter Organization This section lists the replaceable electrical and mechanical parts for the Agilent 668xA series power supplies. (Componentlocation diagrams are located in Chapter 6.) The lists consist of tables organized by assemblies as fol...

90 Replaceable Parts How to Order Parts You can order parts from your local Agilent Technologies, Inc. Sales and Support Office (see the list of offices in the backof this manual). When ordering a part, please include the following information: • the Agilent part number • the part description • the ...

Replaceable Parts 103 Table 5-11. A7 Snubber Assembly, Replaceable Parts Ref. Desig. Agilent Part No. Description ELECTRICAL PARTS C910, 911, 912, 913 6680A, 6681A 0160-0162 CAP .022uF 10% 6682A 0160-6896 CAP .015uF 10% 6683A 0160-4845 CAP 6800pF 10% 6684A 0160-6162 CAP 4700pF 10% R910, 911, 912, 91...

104 Replaceable Parts Table 5-13. A9 Down Programmer/Slow Sense, Replaceable Parts Ref. Desig. Agilent Part No. Description ELECTRICAL PARTS C950, 951 0160-4259 CAP .22uF 10% C952, 953 0160-4048 CAP .022uF 20% C956, 957 0160-4065 CAP .luF 20% C958, 980 0160-4835 CAP .luF 10% 50V D980, 981 1901-1098 ...

Diagrams 115 6 Diagrams Introduction This chapter contains drawings and diagrams for troubleshooting and maintaining Agilent Series 668xA Power Supplies.Unless otherwise specified, a drawing or diagram applies to all models of the series. Wiring connections to externalequipment are shown in the Powe...

118 Diagrams Table 6-3. Test Points (continued) TEST POINT No. & Loc. Signal Tested Measurement and Conditions Bias Board (continued) U308-1 PREF +2.5V U308-5 RESET* Held low for approximately 50 ms at power-on,then goes high. U311-7 FAN DETECT +3V D317 -25V +3V U311-2 FAN_PWN +0.6V A3 FET Board...

Diagrams 119 Table 6-3. Test Points (continued) TEST POINT No. & Loc. Signal Tested Measurement and Conditions A10 Control Board (continued) U600-10 DIVIDER CLOCK (Sheet 3) See Figure 6-1 U601-6 DIVIDER RESET (Sheet 3) See Figure 6-1 U601-3 ON LATCH CLOCK (Sheet 3) See Figure 6-1 U604-3 ON LATCH...

Diagrams 121 Figure 6-2. Circuit Board Cabling Diagram

122 Diagrams Figure 6-3. A1 Front Panel Board, Component and Test Point Location

Figure 6-11. A4 AC Input Board, Component and Test Point Location 9 10 11 12

Figure 6-13. A5 DC Rail Board, Component and Test Point Location 13 14

Figure 6-15. A6 Bias Board, Component and Test Point Location 15 16 17 18 19

Figure 6-25. A10 Control Board, Component and Test Point Location 47 55 44 41 42 46 48 43 63 53 51 50 49 45 38 36 60 62 61 59 54 52 57 58 56 64 37 21 36 22 20 39 40

Backdating 149 A Backdating Manual backdating describes changes that must be made to this manual for power supplies whose serial numbers are lowerthan those listed in the title page to this manual. Look in the following table and locate your Agilent model. Then look at each serial number listed for ...

Backdating 151 Table A-1. A2 GPIB Parts List Ref Desig. Agilent Part No. Description ELECTRICAL PARTS C102-105 0160-4822 Capacitor 1000pF 5% C106 0180-0155 Capacitor 2.2 µ F 20V C107,108 0160-4787 Capacitor 22pF 5% 100V C109-111,114,115,121 0160-5422 Capacitor 0.047 µ F 20% C122 0180-3325 Capacitor ...

Backdating 153 Figure A-1. A2 GPIB Component Parts List

Index 155 Index A A1 Front Panel Board, test header .............................................................................................................................. 57A2 GPIB Board, test header................................................................................................

Index 157 UART PARITY ................................................................................................................................................... 35 error message, selftest ..........................................................................................................