Gebruiksaanwijzing /service van het product 8842a van de fabrikant Fluke
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® 8842A Digital Multimeter Instruction Manual PN 8793 0 9 Date December 1 9 91 Re v .3 7/96 © 1999 Fluke Corporation, A l l rights reserved . Printed in U SA All product n a mes a re t r ad e marks of thei r r espective com p anies.
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i Table of Contents Chapter Titl e Page 1 Introduction and Spec ifications ........................................................ 1-1 1-1. INTRODUCTION ................................................................................ 1-2 1-2. THE 8842A DIGITAL MULTIMETER .
8842A Instruction M anual ii 2-28. Current Fuse Pr otection.................................................................... 2-13 2-29. Offset Measurem ents ....................................................................... 2-14 2-30. EXTERNAL CLEANING .
Contents (c ontinued) iii 3-50. The Serial Poll Reg ister ................................................................... 3-27 3-51. The SRQ Mask ................................................................................. 3-28 3-52. INTERFACE MESSAGES .
8842A Instruction M anual iv 5-15. OHMS CURRENT SOURCE .............................................................. 5-12 5-16. OHMS PROTECTION ......................................................................... 5-13 5-17. OHMS FUNCTIONS ......
Contents (c ontinued) v 6-20. TOLERANCE CHECK ............................................................... 6-18 6-21. AC CALIBRATION AT OT HER FREQUENCIES ................... 6-19 6-22. OPTIMIZING USE OF THE 5450A ..................................
8842A Instruction M anual vi 8-5. Replacem ent Test Leads (TL70A) ................................................... 8-4 8-6. Deluxe Test Lead Kits (Y8134) ....................................................... 8-4 8-7. Slim- Flex Test Leads (Y8140) .
vii List of Tables Table Title Page 2-1. Error Codes ............................................................................................................ 2-9 2-2. Input Ov erload Limits .........................................................
8842A Instruction M anual viii 6-27. AC Signal Tracing ................................................................................................. 6-68 6-28. Truth Table fo r U804 and K2 ..........................................................
ix List of Figures Figure Title Page 1-1. External Dim ensions .............................................................................................. 1-11 2-1. Line Voltag e Selection Se ttings .................................................
8842A Instruction M anual x 4-12. Leakage Resistanc e in High Resi stance Mea surem ent .......................................... 4-16 5-1. Overall Funct ional Block Diagram ........................................................................ 5-5 5-2.
Contents (c ontinued) xi 9-7. IEEE-488 I nterface PCA, Option -05 .................................................................... 9-15 9-8. True RMS AC PCA, Option - 09 .
8842A Instruction M anual xii.
1-1 Chapter 1 Introduction and Specifications Title Page 1-1. INTRODUCTION ................................................................................ 1-2 1-2. THE 8842A DIGITAL MULTIMETER .............................................. 1-2 1-3. OPTIONS AND ACCESSORIES .
8842A Instruction M anual 1-2 1-1 . INTRODUCTION This manu al prov ides compl ete opera ting inst ructions and service i nformat ion for the 8842A. If you want to get sta rted using your 88 42A right away, p roceed to th e operating instructions in Se ction 2.
Introduction and Specifications SPECIFIC ATIONS 1 1-3 1-4. SPECIFICATIONS Specification s for the 884 2A are giv en in Table 1 -1. External dimen sions a re shown in Figure 1-1. Table 1-1. Specifi cations DC VOLTAGE Input Characteristics RESOLUTION RANGE FULL SCALE 5 ñ DIGITS 5 ñ DIGITS 4 ñ DIGITS* INPUT RESISTANCE 20 mV 19.
8842A Instruction M anual 1-4 Operating Characteristics TEMPERATURE COEFFICIENT ........... < (0.0006% of read ing + 0.3 Count) per °C from 0°C to 18°C and 28°C to 50°C. MAXIMUM INPUT ...................................1000V dc or peak ac on any range.
Introduction and Specifications SPECIFIC ATIONS 1 1-5 Accuracy NORMAL (s) READING RATE .............. ±(% of Reading + Number of C ounts). For sinewave i nputs ≥ 10,0 00 cou n ts 1 . FREQUENCY 24 HOURS 2 23±1°C 90 DAY 23±5°C 1 YEAR 23±5°C 2 YEARS ±5°C 20-45 1.
8842A Instruction M anual 1-6 CURRENT Input Characteristics RESOLUTION RANGE FULL SCALE 5½ DIGITS 5½ DIGITS 4½ DIGITS 1 200 mA 2 199.999 m A 1 µ A 10 µ A 2000 mA 1999.99 mA 10 µ A 100 µ A 1. 4½ digits at the fastes t reading rate . 2. The 200mA rang e is avail able for dc current only.
Introduction and Specifications SPECIFIC ATIONS 1 1-7 MEDIUM AND FAST READING RATES........In medium rate, add 50 c ounts to number of counts. In fast reading rate, for sinewave inputs ≥ 1000 ( 4½ digit m ode) counts and frequ encies > 100 Hz , the acc uracy is ±(0.
8842A Instruction M anual 1-8 Accuracy NORMAL (S) READING RATE ............... ±(% of Reading + N umber of C ounts) 1 . RANGE 24 HOURS 23±1 ° C 90 DAY 23±5 ° C 1 YEAR 23±5 ° C 2 YEARS 23±1 ° C 20 Ω 3 0.007 + 30 4 0.009 + 40 4 0.012 + 40 4 0.
Introduction and Specifications SPECIFIC ATIONS 1 1-9 Reading Rates READING RATES WITH INTERNAL TRIGGER (readings per second) POWER LINE FREQUECNCY 1 RATE 50 Hz 60 Hz 400 Hz S 2.08 (.26) 2 2.5 (.3 1) 2 2.38 (.30) 2 M 16.7 (1 .04) 2 20 (1.25) 2 19.0 (1.
8842A Instruction M anual 1-10 EXTERNAL TRIGGER TIMING CHARACTERISTICS The followi ng diagram shows the nom inal tim ing for the v arious pr ocesses which take plac e between a n external trigg er and data s ent out on t he IEEE-488 interf ace. Delays will vary if a s econd trigg er comes before the data handshak e is com plete.
Introduction and Specifications SPECIFIC ATIONS 1 1-11 GENERAL COMMON MO DE VOLTAGE..................1000V dc or peak ac , or 700V rms ac from any input to earth. TEMPREATURE RANGE .......................0 to 50 ° C operating, -4 0 to 70 ° C stora ge.
2-1 Chapter 2 Operating Instructions Title Page 2-1. INTRODUCTION ................................................................................ 2-2 2-2. I NSTALLATION .................................................................................
8842A Instruction M anual 2-2 2-1 . INTRODUCTION This section provide s instruc tions for install ing and opera ting the 8842A. Re fer to Section 4 for measure ment con siderat ions.
Operating Instructions INSTALLAT ION 2 2-3 2-5. Adjusti ng the Handle The handle p rovides two v iewing angles fo r bench-top u se. To ad just its positi on, pull the ends out to a hard stop (about 1/4 inch on e ach side) and rota te it to on e of the fou r stop positions sh own in Figu re 2-2.
8842A Instruction M anual 2-4 f2-04.wmf Figure 2-4. In stalling the Single Rack Mount Kit 2-7 . OPERATING FEATURES 2-8. Power-Up Features When the 8 842A is turned on, all dis play segme nts light up for a bout 2 second s while the instrumen t perfo rms an in ternal se lf-test of its dig ital cir cuitry.
Operating Instructions OPERAT ING FEAT URES 2 2-5 Note that the VA C and mA AC functio ns are avai lable only w ith the True RMS AC option. If this option is a bsent, p ressing th e VAC and mA AC functi on buttons c auses the 8842A to brief ly display an e rror mess age (ERROR 30).
8842A Instruction M anual 2-6 M TRIG triggers a new reading. Enabled in external trigger mode. EXT TRIG toggles between internal and external trigger modes RATE cycles between slow, medium and fast reading rates. Automatically selects the optimum filter for each reading rate.
Operating Instructions OPERAT ING FEAT URES 2 2-7 Line V oltage Selection Switches P ower-Line Fuse P ower-Line Cord Connector HI and LO INPUT T erminals IEEE-488 Interf ace Bus Connector* T ALK ONL Y and IEEE-488 ADDRESS Selection Switches* SAMPLE COMPLETE output TTL-le vel.
8842A Instruction M anual 2-8 2-10. Displ ay Features The 8842A fea tures a vacuu m fluore scent d isplay w ith a nume ric field and annunc iators. The annunciato rs are expl ained in Fig ure 2-5.
Operating Instructions OPERAT ING FEAT URES 2 2-9 Table 2-1. Error Codes ERROR CODE MEANING ERROR CODE MEANING ANALOG SELF-TEST ERRORS OPERATION ERRORS 1 200 VAC, Zero 30 AC funtions av ailible only with 8842A-0 9 True RMS AC option. 2 700 VAC, Zero 31 m A AC or mA DC funtion selected wh ile REAR inputs s elected.
8842A Instruction M anual 2-10 2-12. Overrange Indi cation An input i s overrange if it exceeds the full sca le of th e selected range. In m ost ranges, the 8842A indicate s an input i s overrange by lighting th e OVER annuncia tor and showin g a "1" on the d isplay.
Operating Instructions OPERAT ING FEAT URES 2 2-11 2-16. MANUAL RANGE In manual r ange, the 8842A remains f ixed in the selec ted range un til you sel ect anothe r range or p ress AUTO.
8842A Instruction M anual 2-12 In the con tinuous trigg er mode , the actua l number o f readings d isplay ed per second for each read ing rate i s determ ined by the line-powe r frequency .
Operating Instructions MAKI NG MEAS U REMENTS 2 2-13 2-2 4. MAKING MEASUREME NTS 2-25. Input Overload Protection Limits WARNING TO AVOID SHOCK HAZARD AND/O R INSTRUMENT DAMAGE, DO NOTAPPLY INPUT PO TENTIALS THAT EXCEED THE I NPUT OVERLOAD LIMI TS SHOW N IN TABLE 2-2.
8842A Instruction M anual 2-14 To replace th e fron t panel fuse, first r emove the test lead s. Then press in the lip o f the 2A input te rminal s lightly a nd rotate it 1/4-tu rn counterc lockwise . Spring ten sion will fo rce the fuse and fuse hold er out of t he fron t panel.
Operating Instructions EXTERNA L CLEANING 2 2-15 f2-09.wmf Figure 2-9. Measuri ng Voltage and Res istance f2-10.wmf Figure 2-10. Mea suring Current 2-3 0. EXTE RNAL C LEANING WARNING TO AV OID E LECT RIC SHOC K OR INS TRU MENT DAMA GE, NEVER GET WATER INSIDE THE CASE.
8842A Instruction M anual 2-16.
3-1 Chapter 3 Remote Programming Title Page 3-1. INTRODUCTION ................................................................................ 3-3 3-2. CAPABILITIES ................................................................................... 3-3 3-3.
8842A Instruction M anual 3-2 3-35. ? (Single- Trigger Comm and) ........................................................... 3-20 3-36. INPUT SYNTAX ................................................................................. 3-20 3-37. Defin itions .
Remote Programming INTRODUCTION 3 3-3 NOTE This section contains programming instruc tions for use with the IEEE-488 Interfa ce (Option -05). For ins tallation instructions, refer to the Optio ns and Accessorie s section.
8842A Instruction M anual 3-4 A D D R E S S T A L K O N L Y A5 A4 A3 A2 A1 A D D R E S S T A L K O N L Y A5 A4 A3 A2 A1 A D D R E S S T A L K O N L Y A5 A4 A3 A2 A1 00 0 0 0000 1 1 001011 2 2 0 10110 .
Remote Programming AN OVERV IEW OF RE MOTE O PER ATION 3 3-5 f3-02.wmf Figure 3-2. Remo te Operation Block Diagra m.
8842A Instruction M anual 3-6 Informat ion is tra nsferred be tween blocks by devic e-dependent comm ands. Each command is shown next to a n arrowhead whi ch indicates the resul ting infor mation transfer. Fo r exam ple, Put com mand P0 take s a numb er from the inpu t buffer an d store s it in the pri mary status regi sters.
Remote Programming DEVICE-D EPENDENT COMM AND SET 3 3-7 RANGE COMMANDS R0 Autorange On R1 200 mV, 200 Ω R2 2V, 2 k Ω R3 20V, 20 k Ω R4 200V, 200 k Ω , 200 mA R5 1000V dc, 700V ac, 2 M Ω , 20.
8842A Instruction M anual 3-8 FUNCTON COMMANDS TERMINATOR COMMANDS F1 VDC (Default) W0 Enable CR LF EOI (Default) F2 VAC W1 Enable CR LF Only F3 2 WIRE k Ω W2 Enable CR EOI Only F4 4 WIRE k Ω W3 E.
Remote Programming DEVICE-D EPENDENT COMM AND SET 3 3-9 Device-depende nt command s are device-d ependen t messages . For the 8842A t o receive them, they must be sen t over the IEEE -488 bus when the 8842A is in remote and has been addresse d as a lis tener.
8842A Instruction M anual 3-10 3-10. Fn (Function Commands) The function c ommands dupli cate the f ront panel function butto ns. The 8842A d efaults to F1 on power-up and o n any device -clear co mmand (*, DCL, or SDC ). If F0 is sent t o the 8842A, it is inte rnally conve rted to F1.
Remote Programming DEVICE-D EPENDENT COMM AND SET 3 3-11 Table 3-1. Stat us Data COMMAND OUTPUT STRING MEANING G0 F rst F = 1 – 6 as in Funtio n com mands (Fn) 9 for Self-Test r = 1 – 6 and 8 in R.
8842A Instruction M anual 3-12 3-12. G0 (Get Instrument Confi guration) The G0 command c opies the 88 42A function, rang e, read ing rate, and tr igger mode into the outpu t buffer i n the fo rmat shown in Figure 3-6 . The four dig its retu rned represe nt the argumen ts for the equivalen t F, R, S, and T command s, as shown in Tab le 3-1.
Remote Programming DEVICE-D EPENDENT COMM AND SET 3 3-13 3-15. G3 (Get User-Defi ned Message) The G3 comm and load s the output buffer w ith the us er-define d message stored in calibration memory dur ing the cal ibration proc edure. The me ssage consi sts of 16 ASCII characters , as shown in Fi gure 3-6.
8842A Instruction M anual 3-14 3-17. G5 (Get I AB Stat us) The G5 command loads th e output buffe r with the IAB s tatus in the format shown in Figure 3-6.
Remote Programming DEVICE-D EPENDENT COMM AND SET 3 3-15 3-20. G8 (Get Instrument Identifi cati on) The G8 command c opies the 88 42A inst rument ide ntificatio n into the outpu t buffer in the format shown in F igure 3 -6. The identif ication is represen ted by four co mma separat ed fields tha t are int erpreted in Table 3 -1.
8842A Instruction M anual 3-16 "N3120 P0" Identical to F3 R1 S2 T0. Selec ts 2 WIRE k Ω function, 200 Ω r ang e, fast samp le rate, con tinuous t rigger. The P0 command allows broad side loadi ng of the Functio n, Range, Reading Ra te, and Trigger Mode comma nds (F, R, S, a nd T).
Remote Programming DEVICE-D EPENDENT COMM AND SET 3 3-17 etc. All o f these st rings resul t in the same valu e being us ed for the n ext calib ration step.
8842A Instruction M anual 3-18 3-29. Tn (Trigger Mode Commands ) The Trigger Mo de command s duplicate th e front pan el EX TRIG button. In addition, the commands ca n enable or disable th e rear p anel trig ger and the automa tic settl ing time delay.
Remote Programming DEVICE-D EPENDENT COMM AND SET 3 3-19 The trigger mode can be r ead using th e G0 command. T he 8842A defaul ts to T0 on bo th power-up and any d evice-cle ar comm and (*, DCL, or SDC). 3-30. Wn (Terminator Commands) The Terminator c ommands s elect what terminator s the 8842A appen ds to ev ery output string.
8842A Instruction M anual 3-20 Error mess ages are ind icated by an exponen t of +21. For more abou t error messages , see pa ra gra ph 3 - 40. Since the 8842A is rese t at the en d of the se lf-tests , the Z0 co mmand should b e the la st command in a given command string.
Remote Programming INPUT SYNTAX 3 3-21 3-37. Defi niti ons • Output co mmands: Comman ds which load data into the output bu ffer. The ou tput commands a re: the Get com mands (G0 th rough G8); the Single-Tr igger Command (?); the Con tinuous Trigg er command (T0 ); and G roup Execute Tr igger (GET), no t to be confused wi th the Get co mmands.
8842A Instruction M anual 3-22 DEVICE-DEPENDENT MESSAGES Single-character Comman ds Bn Cn Dn Fn G n Pn Rn Sn Wn Xn Yn Z n Eac h of these c ommands requires the single numeric dig it (n).
Remote Programming INPUT SYNTAX 3 3-23 Illegal co mmands ( e.g., F9) gen erate an e rror mess age, but are oth erwise igno red, and do not affect the ins trument’ s configurat ion. Example Explanation "* F9" This would load the ou tput bu ffer with an erro r message and select F 1 (establis hed by th e * comma nd).
8842A Instruction M anual 3-24 In this incorr ec t examp le, the IN PU T state me nt is loca ted incor rec tly fo r readi ng the measurem ent data from line 100. The new inp ut comma nd string "F4" disallows the reading o f data fro m the outpu t buff er.
Remote Programming OUTPUT DATA 3 3-25 Because th e 8842A gives pr iority t o input p rocessing, it co mpletely p rocesses a ll characters in the inpu t buffe r befo re it load s the ou tput buffer. Wh en the ou tput buffe r is loaded, th e Data A vailable b it in the se rial poll registe r is set t rue.
8842A Instruction M anual 3-26 NOTE In the fa st (F) read ing rate, th e least s ignifican t digit is alwa ys zero, a nd should be disr egarded when in terpreti ng accuracy sp ecification s. 3-45. O VERRANGE I NDICATION If a read ing is ove rrange ( ≥ 2 00,000 counts ), the m easuremen t data has the fo llowing format: ±9.
Remote Programming SERVIC E REQU ESTS 3 3-27 1. Status data (from G0, G1, G3, G4, G5, G6, G7 and G8) 2. Error mess ages (if a n error ex ists) 3. Numeric d ata ( from G2 o r a tr igger) This means t hat an erro r message always over rides nume ric data, but s tatus data i s sent even in th e presence o f an error.
8842A Instruction M anual 3-28 BIT: 8 7 6 5 4 3 2 1 0 RQS ANY ERROR DATA AVAILIBLE CAL STEP COMPLETE FRONT PANEL SRQ 0 OVER- RANGE DECIMAL VALUE: 64 32 16 8 4 2 1 Bit Name Set C leared 1 Overrange An .
Remote Programming INTERFACE ME SS AG E S 3 3-29 The SRQ mask can ena ble any com bination o f serial p oll registe r bits 1 through 6. Its six - bit binary representation is ANDed bit-for-bit with serial poll register bits 1 through 6 whenever the ou tput buffe r is lo aded.
8842A Instruction M anual 3-30 IFC Interface C lear -- A uniline m essage w hich clea rs only the interfac e (not the 8842A) by placin g it in a known quiescent state. REN Remote Enable -- A uni line mess age which, wh en rece ived with MLA, swit ches the 8842A to remote.
Remote Programming REMOTE CALIBR ATION 3 3-31 6. Configure the 8842A with the front panel con trols. The 8842A read s the TALK ONLY bit swit ch on power-up and when it recei ves the interface command IFC . You can there fore set the TALK ON LY switch t o 1 after pow er- up as long as you then se nd the 8842A the IFC command.
8842A Instruction M anual 3-32 Table 3-3. Immed iate-Mode Comma nds for Various Controllers FUNTION PERFOR MED FLUKE-BAS I C on 1720A or 1722A HP-HPL on HP9825 Calculator HP-BASI C on HP9816-PC and HP.
Remote Programming EXAMPLE PROG RAMS 3 3-33 f3-10.wmf Figure 3-9. Example Program.
8842A Instruction M anual 3-34 f3-11.wmf Figure 3-10. Exampl e Program: Taki ng Readings with Loc al Control.
Remote Programming EXAMPLE PROG RAMS 3 3-35 f3-12.wmf Figure 3-11. Exampl e Program: Using t he Serial Poll Regist er.
8842A Instruction M anual 3-36 f3-13.wmf Figure 3-12. Exampl e Program: Record Errors Durin g Selftest.
Remote Programming EXAMPLE PROG RAMS 3 3-37 f3-14_01.wmf Figure 3-13. Exampl e Programs: Using the IBM PC.
8842A Instruction M anual 3-38 f3-14_01.wmf Figure 3-14. Exampl e Programs: Using the IBM PC (cont).
Remote Programming EXAMPLE PROG RAMS 3 3-39 f3-14_02.wmf Figure 3-14. Exampl e Programs: Using the IBM PC (cont).
8842A Instruction M anual 3-40 f3-14_03.wmf Figure 3-14. Exampl e Programs: Using the IBM PC (cont).
Remote Programming EXAMPLE PROG RAMS 3 3-41 f3-14_04.wmf Figure 3-14. Exampl e Programs: Using the IBM PC (cont).
8842A Instruction M anual 3-42 f3-14_05.wmf Figure 3-14. Exampl e Programs: Using the IBM PC (cont).
Remote Programming EXAMPLE PROG RAMS 3 3-43 f3-14_06.wmf Figure 3-14. Exampl e Programs: Using the IBM PC (cont).
8842A Instruction M anual 3-44 f3-14_07.wmf Figure 3-14. Exampl e Programs: Using the IBM PC (cont).
Remote Programming EXAMPLE PROG RAMS 3 3-45 f3-14_08.wmf Figure 3-14. Exampl e Programs: Using the IBM PC (cont).
8842A Instruction M anual 3-46 f3-14_09.wmf Figure 3-14. Exampl e Programs: Using the IBM PC (cont).
Remote Programming EXAMPLE PROG RAMS 3 3-47 f3-14_10.wmf Figure 3-14. Exampl e Programs: Using the IBM PC (cont).
8842A Instruction M anual 3-48 f3-14_11.wmf Figure 3-14. Exampl e Programs: Using the IBM PC (cont).
Remote Programming EXAMPLE PROG RAMS 3 3-49 Table 3-4. ASCII/IEEE Std 488-1978 Bus Codes.
8842A Instruction M anual 3-50 NOTE For the examp les using the Fluke 1720A o r 1722A, the 8842A is plugged into port 0. T he port i s initia lized b y the IN IT statement, w hich send s IFC (interfac e clear).
4-1 Chapter 4 Measurement Tutorial Title Page 4-1. INTRODUCTION ................................................................................ 4-2 4-2. DC VOLTAGE MEASUREMENT ..................................................... 4-2 4-3. Circuit L oading Erro r .
8842A Instruction M anual 4-2 4-1 . INTRODUCTION This section discus ses conside rations and techn iques to help you use the 8842A effective ly. Among othe r thing s, this se ction discu sses sourc es of erro r which ar e an inheren t part of th e measure ment proc ess and wh ich occu r for all multim eters.
Measurement Tutoria l DC VOLT AGE MEA SUREM ENT 4 4-3 The input impedance o f the 884 2A is 10 M Ω in th e 200V and 1000V dc ranges, and is greater th an 10,000 M Ω in the 20 mV, 200 mV, 2V, and 20V ranges. The refore, for the 8842A, circuit loading error is less than 0 .
8842A Instruction M anual 4-4 3. Allow th e displaye d reading to settle. 4. Press the OFFSET button. 5. Remove th e resi stor. 6. Proceed with t he desired me asure ment. Example: Measure a 1.5V source wi th 1 M Ω s ource im pedance, cor recting fo r input bias cu rrent.
Measurement Tutoria l RESISTANCE ME AS UREM ENT 4 4-5 The test cur rent and full-sca le voltag e for each r esistanc e range are sh own in Tab le 4-1. Since the H I INPUT tes t lead is po sitive w ith respe ct to the LO INPUT lea d, these test leads are no t inte rchangea ble when a se miconducto r device is being measured.
8842A Instruction M anual 4-6 f4-04.wmf Figure 4-4. Wire Ohms Measur ement Table 4-1. Ohm s Test Current RANGE T EST CURRENT FULL SCALE VOLTAGE 20 Ω 1 mA 0.02V 200 Ω 1 mA 0.2V 2 k Ω 1 mA 2.0V 20 k Ω 100 µ A2 . 0 V 200 k Ω 10 µ A2 . 0 V 2000 k Ω 5 µ A 10.
Measurement Tutoria l RESISTANCE ME AS UREM ENT 4 4-7 NOTE In the 2 M Ω and 20 M Ω ranges o f 4-wire ohms, the voltage acr oss the unknown resistance is sensed be tween the HI SENSE and LO INPUT terminals.
8842A Instruction M anual 4-8 4-12. A PRECISIO N CURRENT SO URCE The ohms cu rrent sou rce (the int ernal cu rrent sour ce used in the ohms functions ) makes a useful trou bleshoo ting too l in itself . It has exc ellent line arity and t emperatu re stabi lity.
Measurement Tutoria l REDUCING THERMAL VOLTAGES 4 4-9 f4-05.wmf Figure 4-5. Burden Voltage Error Calculation 4-1 4 . REDUCING THERMAL VOL TAGES When mak ing very low- level d c measure ments, the rmal vol tages can p resent an additional source o f error.
8842A Instruction M anual 4-10 4. Use cautio n when handling t he circu it unde r test. 5. Wait for the circuit to reach the rm al equ ilibr iu m. (Therm a l volta ges are gene ra ted only where there is a tempera ture gradi ent.
Measurement Tutoria l AC VOLTAGE AND CURRENT MEASUR EM ENT 4 4-11 f4-06.wmf Figure 4-6. Waveform Co mparison Chart Since average -responding mete rs have been in use fo r so long, you may hav e accumulat ed test or ref erence data ba sed on them. Th e conversion facto rs in Figure 4-6 should help you convert be tween the two m easurement m ethods.
8842A Instruction M anual 4-12 4-18. Crest Factor Crest fa ctors are useful for expres sing th e abil ity of an instru ment to measure a variety o f waveform s accurate ly. The c rest factor o f a wavefo rm is th e ratio of its pe ak voltage to its rms voltag e.
Measurement Tutoria l AC VOLTAGE AND CURRENT MEASUR EM ENT 4 4-13 measurem ents, for i nstance, can not be made with dc c oupling. R emember, how ever, th at when the 8842A mea sures sign als with th e ac functi ons, the rea ding on the d isplay does not include the dc co mponent (i f one ex ists).
8842A Instruction M anual 4-14 The zero-inpu t erro r is quick ly reduced wh en the inpu t is incr eased. The r ms converter error (a dc error) and the in ternally g enerated no ise (a random ac e rror) ar e both uncorrelat ed with the input signa l.
Measurement Tutoria l MAKING ACCURAT E HIGH-R ESISTANCE MEAS UREMENT S 4 4-15 f4-10.wmf Figure 4-10. Shi elding for Low Voltage M easurements For low-l evel resi stance mea surement s, connect th e test lead s hield ing as shown in F igure 4-11. Use th e 4-wire oh ms function to mi nimize the e rror c aused by the resistanc e of the test leads.
8842A Instruction M anual 4-16 f4-12.wmf Figure 4-12. L eakage Resistance i n High Resistance M easurement.
5-1 Chapter 5 Theory of Operation Title Page 5-1. INTRODUCTION ................................................................................ 5-3 5-2. OVERALL FUNCTIONAL DESCRIPTION ...................................... 5-3 5-3. DETAILED CIRCUIT DESCRIPTION .
8842A Instruction M anual 5-2 5-36. POWER SUPPLY ................................................................................ 5-25 5-37. IEEE-488 I NTERFACE (OPTION -05)............................................... 5-26 5-38. Out-Guard Mic rocomputer.
Theory of Operation INTRODUCTION 5 5-3 5-1 . INTRODUCTION This section presen ts an overa ll func tional des cription o f the 8842A, fo llowed by a detailed c ircuit de scription. T he descrip tions a re supporte d by simpl ified sch ematics in text and by the comp lete sch ematics in S ection 10.
8842A Instruction M anual 5-4 5-3. DETAIL ED CIRCUIT DESCRIPTION The follow ing parag raphs give a detailed ci rcuit d escript ion of each o f the fun ctional blocks in Figu re 5-1. Fo r clarity, meas urement ranges are referred to as r1, r2, r3, etc.
Theory of Operation DC SCALING 5 5-5 f5-01.wmf Figure 5-1. Overal l Functional Block Diagram.
8842A Instruction M anual 5-6 5-5. VDC Scaling Scaling is pe rformed in the VDC funct ion by two precis ion res istors network s (Z301 and Z302). These components are configured by relay K301, sw itchin g transistor Q 311, and quad analog switches U302A and U301B to provide t he correct sca ling for e ach range.
Theory of Operation DC SCALING 5 5-7 In the 20 mV, 200 mV and and 2V ranges, the input voltage is applied di rec tly to the T/H Amplifier via Q310, Q311, and U30 1B.
8842A Instruction M anual 5-8 5-9. TRACK/HOLD CIRCUIT The Track/Hold (T /H) ci rcuit pres ents a stable voltage to the A/D Convert er during t he input period of the A /D conversion cycle. The circu it also pr ovides a ga in of 100 in the 20 mV, 20 Ω and 200 mA ranges, and a gain o f 10 in the 20 0 mV dc, 200 Ω , and 2000 mA dc ranges.
Theory of Operation TRACK/HOLD CIRCUIT 5 5-9 f5-04.wmf Figure 5-4. Track/Hold Cir cuit Configuration s.
8842A Instruction M anual 5-10 f5-05.wmf Figure 5-5. Ti ming Diagram for One A/D Cycl e 5-10. Track Confi guration In the trac k config uration (F igure 5-4A), the T/H circu it funct ions as a non-in verting buffer. The vo ltage on C3 08 tracks the s caled dc inp ut voltage.
Theory of Operation PRECISION VOLTAG E R EFERENC E 5 5-11 5-11. Settli ng Confi gurati on The circuit assumes a settling configu ration be tween the track and ho ld configur ations. The circuit assumes t he configur ation in Figur e 5-4B for unity g ain and the configurat ion in Figure 5-4C for gai n of 10.
8842A Instruction M anual 5-12 Resistor R701, p recision resistor netwo rk Z701, and tr ansistor/zen er diode co mbination U701 are produced as a matc hed set so t hat the out put of U702A is p recisely -7.00000V. This outpu t is remote ly sensed at th e pins o f the custo m A/D IC (U101).
Theory of Operation OHMS PR OTECTION 5 5-13 The second stag e (U404, preci sion resi stor network Z401, and analo g switches U402 and U403) is a cur rent ampl ifier whose gain is con trolled by the In-Guar d µ C. Th e In-Guard µ C sets th e output curren t for each range by controlling U402 and U403.
8842A Instruction M anual 5-14 f5-08.wmf Figure 5-8. Ohms S caling.
Theory of Operation A/D CONVERT ER 5 5-15 The voltage se nsed at the INPUT te rminals is sca led as show n by the si mplified switch table in Fig ure 5-8. (Ref er to the track peri od of the track /hold cycle , during which t he scaled inpu t voltag e is samp led.
8842A Instruction M anual 5-16 f5-09.wmf Figure 5-9. Anal og-to-Digital Converter The convers ion process is broken up into an autozero pe riod fo llowed by five measurem ent interv als. (A ti ming diagr am is shown in Figure 5-5. ) Six bits of the final A/D sampl e are obtai ned duri ng each inte rval.
Theory of Operation A/D CONVERT ER 5 5-17 f5-10.wmf Figure 5-10. First Rem ainder-Store Period This fiv e-interval p rocess thus genera tes five n ibbles which are process ed by the In- Guard µ C to produce one A/ D sample. Af ter the f ifth nibble i s generated, U101 interrupt s the In-Guard µ C over line INT.
8842A Instruction M anual 5-18 The bit-switches determ ine the outpu t voltage o f U102B by contro lling the b inary ladd er network. The gain of U102B is set by the ratio of a prec ision feed back resis tor (Z101-7, - 8) and the equ ivalen t output re sistance o f the ladde r network.
Theory of Operation KEYBO ARD 5 5-19 f5-12.wmf Figure 5-12. Vacuum Fluorescent Displa y The Digital Con troller sequential ly enables the G lines b y applying +30V dc ( nominal). When a G line is enabled, el ectrons flow fro m the fi lament to the enabled grid.
8842A Instruction M anual 5-20 f5-13.wmf Figure 5-13. Digital Contro ller Block Diagram.
Theory of Operation DIGITAL CONTROLLER 5 5-21 5-28. In-Guard Microcomputer The In-Guard Microco mputer ( µ C) is a s ingle-chip Z8 microco mputer con taining 4K bytes of ROM, 144 b ytes of RA M, a UART, and fou r 8-bit I/O ports. It comm unicates with the res t of the in strume nt via th e interna l bus and dedi cated I/O line s.
8842A Instruction M anual 5-22 f5-14.wmf Figure 5-14. Read/Write Timing Diagrams for Internal Bus.
Theory of Operation DIGITAL CONTROLLER 5 5-23 5-29. Function and Range Control The In-G uard µ C configures the DC Sca ling circui t, the Track/Ho ld circu it, and the Ohms Curre nt Source to provide the proper input sw itching, sca ling, and f iltering fo r each functio n, range, and reading rate.
8842A Instruction M anual 5-24 5-32. Keyboard/Di splay Control Keyboard/Display Con troller U212 comm unicates with the In-Guard µ C over th e inte rnal bus. During a µ C write cyc le, address line A0 t ells U212 w hether to c onsider da ta being sent by th e µ C as config uration co mmands or as d isplay dat a.
Theory of Operation POWER SU PPLY 5 5-25 The circuit in Figu re 5-15 has two stable st ates, corr esponding to output h igh (+5V ) and output low (0V). If the output is high, the voltage pr esent a t the non-in verting input of op amp A is approx imately +140 mV.
8842A Instruction M anual 5-26 5-3 7 . IEEE-488 INTERFACE ( OPTION -05 ) The IEEE-488 Inte rface has five majo r parts, a s shown in the b lock diagram in Figure 5- 16. All co mponents ar e contained in a single printed c ircuit as sembly (PCA). R eferen ce designat ions are nu mbered in the 900 seri es.
Theory of Operation TRUE RMS AC (OPTION -0 9) 5 5-27 5-41. Si gnal Conditi oning The SAMPLE COMPLETE and EXT TRIG signals (J903 and J904) are conditioned b y U909. Diodes CR903, CR904, CR905, an d CR906 and resi stors R917 and R91 8 provide protection from exce ssive vo ltages.
8842A Instruction M anual 5-28 U806A, U806B, and a vo ltage divid er (R804 and R805) pr ovide gain whi ch is selec ted for each rang e by the analog switc hes in U804. The conf iguration for each ra nge is show n in Figure 5-17. (In th is figure, th e CMOS analo g switches are represented by mechan ical switches.
Some semiconductors and custom IC's can be damaged by electrostatic discharge during handling. This notice explains how you can minimize the chances of destroying such devices by: 1. Knowing that there is a problem. 2. Leaning the guidelines for handling them.
5. USE STATIC SHIELDING CONTAINERS FOR HANDLING AND TRANSPORT. 6. DO NOT SLIDE S.S. DEVICES OVER ANY SURFACE. 7. AVOID PLASTIC,VINYL AND STYROFOAM IN WORK AREA. 8. WHEN REMOVING PLUG-IN ASSEMBLIES HANDLE ONLY BY NON-CONDUCTIVE EDGES AND NEVER TOUCH OPEN EDGE CONNECTOR EXCEPT AT STATIC-FREE WORK STATION.
6-1 Chapter 6 Maintenance Title Page 6-1. INTRODUCTION .................................................................................. 6-3 6-2. PERFORMANCE TEST ........................................................................ 6-4 6-3. Diagnostic Self- T ests .
8842A Instruction M anual 6-2 6-35. EXTERNAL T RIGGER POLARITY SELECTION (Option -05 Only) 6-36 6-36. TROUBLESHOOTING ......................................................................... 6-36 6-37. Initial Troub leshoot ing Procedure.............
Maintenance INTRODUCTION 6 6-3 WARNING THESE SERVICE INSTRUCTI O NS ARE FOR USE BY QUALIFI ED PERSONNEL ONLY. TO AVOID ELECTRI C SHOCK, DO NOT PERFORM ANY PRO CEDURES I N THIS SECTION UNLESS YOU ARE QUALIF I ED TO DO SO. 6-1 . INTRODUCTION This section presen ts mainte nance in formation for the 8842A.
8842A Instruction M anual 6-4 AC Calibrator Fluke 5700A a nd Fluke 57 25A Minimum Required Acc uracy (By Range) Frequency Range 1, 10, 100 mV 1 1, 10, 100V 2 1000V 2 20 Hz – 30 Hz .1 + .005 .1 + .005 .12 + .005 30 Hz – 20 k Hz .02 + 10 0.2 + .002 .
Maintenance PERFORMANC E TE ST 6 6-5 To initiate the self-tests, pres s the SRQ button for 3 se conds. The TEST annun ciator will then light up, and the 8842A will run through the analog tests in sequen ce. Each test number is d isplaye d for about 1 second.
8842A Instruction M anual 6-6 f6-01.wmf Figure 6-1. DC Calibrat ion Connections Table 6-2. DC Volt age Test Displayed Read ing SLOW MEDIUM FAST STEP RANGE INPUT (V dc) MIN MAX MIN MAX MIN MAX A 1 20 mV 0V (short) -0.0030 +0.003 0 -0.0050 +0.005 0 -0.030 +0.
Maintenance PERFORMANC E TE ST 6 6-7 6-5. AC Voltage Test (Opti on -09 Only) The follow ing procedur e may be used to ver ify the accu racy of th e VAC func tion: 1. Ensure the 8842A is on and warm ed up for at least 1 hou r. 2. Select the VAC fun ction and th e slow (S) read ing rate.
8842A Instruction M anual 6-8 Table 6-4. Hig h-Frequency AC Vo ltage Test INPUT TEST LIMITS (IN VOLTS) STEP NUMBER RANGE VOLTAGE FREQUENCY ERROR IN COUNTS MIN MAX 1 200 mV 0.010000V 50 kHz 169 09.831 m VAC 10.169 mVAC 2 * 200 mV 0.010000V 100 kHz 350 09.
Maintenance PERFORMANC E TE ST 6 6-9 Table 6-5. Re sistance Test Error From Input 1 (in counts) Step Range Input (Nominal) Slow Medium Fast 2 12 0 Ω 3 0 Ω (s hort) ±40 ±60 ±20 22 0 Ω 3 10 Ω.
8842A Instruction M anual 6-10 6-8. AC Current Test (Option -09 Only) The follow ing procedure ma y be used to test the mA AC function: 1. Ensure the 8842A is on and warm ed up for at least 1 hou r. 2. Select the mA AC function. 3. Connect the AC Curr ent Source t o provid e a current inp ut to the 2A an d LO INPUT terminal s.
Maintenance CALIBRATIO N 6 6-11 6-10. Basic Calibration Procedure The basic cal ibration proc edure consists of the fol lowing four p arts. These parts must b e performed in the orde r shown. 1. Initial P rocedure . 2. A/D Calibration. 3. Offset an d Gain C alibration for each fun ction and ra nge.
8842A Instruction M anual 6-12 f6-03.wmf Figure 6-3. Cali bration Functions The following func tio ns are inapp rop ri ate dur ing calibra t ion, and are the refo re unavailable : • Offse t • Autorangin g • External T rigger • Front Pane l Trigger • Front pane l SRQ (Under loca l control) • Diagnosti c self-t ests 6-12.
Maintenance CALIBRATIO N 6 6-13 2. Each time the 884 2A promp ts you for a reference sou rce, apply th e requested source to the HI and LO INPUT terminal s, and press the STORE button. When STO RE is pressed, the n umer ic display field blan ks while the 8842A performs the nece ssary calcula tions.
8842A Instruction M anual 6-14 The A/D Calib ration procedu re is an itera tive proce ss. Each pass through the p rocedure uses the constan ts sto red prev ious ly and improve s them.
Maintenance CALIBRATIO N 6 6-15 NOTE To use referen ce sourc es that diff er from t he prompte d values, se e Storin g Variable Inputs later in th is secti on. 4. After th e last ran ge is cal ibrated, th e 8842A begins t aking r eadings in the highest range so tha t you may ver ify its cal ibration.
8842A Instruction M anual 6-16 5. The calib ration pro cedure is now comple ted. Exit th e calibra tion mode b y pressing the CAL ENA BLE switch, a nd attach a calibrat ion certi fication sticker o ver the CA L ENABLE switch. 6-15. Advanced Features and Special Considerations Table 6-11.
Maintenance CALIBRATIO N 6 6-17 6-17. CALIBRATI NG I NDIVIDUAL RANG ES During Offs et and Gain an d High-Frequen cy AC Calibration, it is poss ible to calib rate individual ly selected r anges. This f eature does not apply to the mA DC and mA AC function s and is not permit ted during A/D Ca libratio n.
8842A Instruction M anual 6-18 1. If you ju st comple ted the Offset and Gain o r High-Frequency AC Cal ibration for an entire func tion (not just one ra nge), th e range but tons can be use d to chan ge ranges in order to ver ify all r anges were ca librated correctly.
Maintenance CALIBRATIO N 6 6-19 If ERROR 41 occurs, th e mos t likely cause is that t he referen ce inpu t is incor rect (e.g., has the wro ng polarity). If the input is i n fact cor rect, ref er to the Tr oubleshoot ing heading in th is sec tion. Table 6-13.
8842A Instruction M anual 6-20 readings. (In remo te calib ration, the averaged va lue can be st ored in the contro ller.) Record the value. 4. Select the "100 Ω " output fro m the 54 50A, and measu re this va lue as in step 3. 5. Find and re cord the nu merical d ifferenc e between the values calculated in steps 3 and 4.
Maintenance CALIBRATIO N 6 6-21 Table 6-14. Comma nds Used During r emote Calibration FRONT PANEL FEATURE CORRESPONDING COMMAND COMME NTS Display G2 Loads the c alibration pr ompt into th e output buff er. Not valid when the 88 42A is taking v erificatio n readings.
8842A Instruction M anual 6-22 1. In remo te calibrat ion, you can s tore a 16-ch aracte r message in the cal ibration memory which can be read by th e syste m controlle r. Possible uses in clude storing the calib ration dat e, instru ment ID, etc. 2.
Maintenance CALIBRATIO N 6 6-23 6-24. TIMI NG CO NSIDERATIO NS Table 6-15. Error Numbers W hich Are Displa yed When Co mmands Are Not V alid CALIBRATION MODE COMMAND NORMAL MODE SELFTEST A/D CAL OFFSE.
8842A Instruction M anual 6-24 The C0 command c an take u p to 22 second s. If du ring th is time the contro ller cont inues to send th e 8842A more c ommands, the com mands may fill up th e 8842A’ s input buffe r. If this happ ens, error s will proba bly occu r.
Maintenance DISASSEM BL Y PROCEDU RE 6 6-25 f6-05.wmf Figure 6-5. Example A/D Calibration Program 6-2 7. DISASSE MBLY PR OCEDURE WARNING TO AVOID ELECTRI C SHOCK, REMO VE THE POW ER CORD AND TEST LEADS BEFORE DISASSEM BLI NG THE INSTRUMENT. OPENI NG CO VERS MAY EXPOSE LIVE PARTS.
8842A Instruction M anual 6-26 6-28. Case Removal 1. Remove th e grounding sc rew fro m the bott om of the c ase. Remo ve two re ar bezel mountin g screws. (See Figure 6-6A.) 2. While hold ing the fron t panel, slide the case and re ar bezel of f the chass is (Se e Figure 6-6B).
Maintenance DISASSEM BL Y PROCEDU RE 6 6-27 f6-06_2.wmf Figure 6-6. 8842A Dis assembly (cont).
8842A Instruction M anual 6-28 f6-06_3.wmf Figure 6-6. 8842A Dis assembly (cont).
Maintenance DISASSEM BL Y PROCEDU RE 6 6-29 f6-06_4.wmf Figure 6-6. 8842A Dis assembly (cont).
8842A Instruction M anual 6-30 6-29. True RMS AC PCA Removal (Option -09 Only) The True RMS AC PCA should b e remov ed by revers ing the la st three s teps in Figu re 809-1 (see Sec tion 8). 1. Release the T rue RMS AC PCA fro m the chass is by pull ing the four pla stic la tches upward (Figure 809-1E ).
Maintenance DISASSEM BL Y PROCEDU RE 6 6-31 b. Unplug the ribbon cable from the Main PCA and lift out the LINE SET PCA. 9. Remove the push rod fo r the CAL ENABLE switch as f ollows (Figu re 6-6H ): a.
8842A Instruction M anual 6-32 6-32. Front Panel Disassembly 1. Holding th e chassis ve rticall y (with the front panel downward), remove th e mounting screws f rom the fou r corners o f the Displ ay PCA (F igure 6-7A ).
Maintenance REAS SEMBLY PROCE DURE 6 6-33 NOTE When insta lling the Mai n PCA, guide the r ear ribbon cab le around th e shield connec ted to the rear pane l so tha t the cable is next to the side o f the chassis. Mak e certa in that th e cable is no t pinched be tween the shield and the Main PCA.
8842A Instruction M anual 6-34 f6-07.wmf Figure 6-7. Front P anel Disassemb ly.
Maintenance REAS SEMBLY PROCE DURE 6 6-35 f6-08.wmf Figure 6-8. Remo ving the Display Window CAUTION Make certain that the CAL ENABLE switch shaft is in the out (disabled) positi on after the CAL ENABLE push rod is installed. If the 8842A is switched on with the CAL ENABLE switch in the enabled position, the 8842A may require recalibration.
8842A Instruction M anual 6-36 WARNING TO AV OID E LECT RIC SHOC K, E NSU RE T HAT THE GROUNDI NG SCREW IS FIRMLY ATTACHED TO THE CASE BOTTOM. 6-3 4 . INTERNAL FUSE REP LACEMENT CAUTION For fire protection, use exact fuse replacements only. The 8842A has an internal 3A 600V s low-blow fuse (F301) in se ries with the 2A input terminal .
Maintenance TROUBLESHOOTI NG 6 6-37 If the d isplay light s up, perform t he self-tes t by pressi ng the SRQ button for 3 second s. (Remember, the inpu t term inals mus t be disconne cted fro m the test le ads du ring the s elf- tests. O therwise, th e 8842A may indica te errors are presen t.
8842A Instruction M anual 6-38 Table 6-16. Ov erall State Table t6-16_1.wmf.
Maintenance TROUBLESHOOTI NG 6 6-39 Table 6-16. Ov erall State Table ( cont) t6-16_2.wmf.
8842A Instruction M anual 6-40 Table 6-17. Cir cuitry Tested by th e Analog Self-Tests t6-17.wmf Some fa ilures w ill cause many se lf-test s to fail . If th is occurs, the fau lt is usua lly in the Track/Hold circuit, the A/D Convert er, the D igital Contro ller c ircuit, o r the Power Supply.
Maintenance TROUBLESHOOTI NG 6 6-41 A failure in the instrum ent may cau se the 8842A to display rando m pattern s or nothing at all. Usua lly, analog cir cuit failur es do not cau se the disp lay to go bla nk or display ra ndom patterns.
8842A Instruction M anual 6-42 6-39. Sel f-Test Descripti ons Table 6-18. S elf-Test Voltages TEST NUMBER T EST POINT VOLTAGE 1 TP803 ±5 mV dc 2 TP803 ±5 mV dc 3 TP803 ±5 mV dc 4 TP103 T/H output wav eform for zero in put (Fig ure 6-14) 5 TP302 ±5 mV dc 6 TP302 ±5 mV dc 7 TP302 +50 mV dc ty pical 8 TP302 +11.
Maintenance TROUBLESHOOTI NG 6 6-43 Configures th e 8842A in the mA DC function an d the slow re ading rate, and measur es the reading acro ss the 0.1 Ω current shu nt. This test should be fa irly immu ne to ou tside noise because the to tal drivin g impedanc e is typic ally les s than 1 k Ω .
8842A Instruction M anual 6-44 These tests p ut the 8 842A in th e respec tive range of the 2-wi re ohms fun ction. They check that ea ch range of the Ohms Curr ent Source ha s enough co mpliance voltage to overload the dc front end . • TEST 15: 1000 VDC + X10 T/H + 20 M Ω Puts the Oh ms Current So urce in th e 500 nA range.
Maintenance TROUBLESHOOTI NG 6 6-45 • TEST 28: External Program M emory (U222) A two-by te check su m is calcu lated ov er the ent ire 4K Extern al Program Memory an d compare d with th e checksum b ytes at th e end of that memory. A specia l add and shift algorithm minimize s the possib ility of double erro rs canc elling.
8842A Instruction M anual 6-46 programme d as inputs to preve nt content ions between them and th e outputs f rom other ICs whi ch drive the m. Data com ing into a ll µ C inputs (except pin 38) is ignored.
Maintenance TROUBLESHOOTI NG 6 6-47 1. Power supplies : +5V dc at U202-1; 0V dc U202-11. 2. µ C clock output : 8 MHz at U202-2,-3. 3. Trigger lin e U202-40 (TP 201): Square w ave, 50% d uty, low 0V, h igh 3.8V (nominal). The p eriod of the trigger signal shou ld be 12.
8842A Instruction M anual 6-48 16, -18, -21, -25 are the same as Wave form B. The wave forms should be inter rupted every 1.5 sec f or 0.2 sec due to inter rupts from th e watchdog time r. (Note: XU222 p ins refer to a 2 8-pin so cket.) 6-45. Calibration Memory (U220) Sync on U219-3.
Maintenance TROUBLESHOOTI NG 6 6-49 possible to freeze th e display, i t should sti ll be possib le to ob serve the wav eform s at U215, U213, U221, and U211 as d escrib ed in the fo llowing par agraphs. To freeze the display, t urn off the instr ument, pre ss the PO WER switch a nd within 1 second pre ss the SRQ butt on.
8842A Instruction M anual 6-50 Check for the same wavefor ms at outp uts U215-11 th rough U215-18. (Howe ver, the hig h level should be approx imately 30V.) If these wav eforms a re OK, then stro be decoder U213 and display control U212 a re OK in this regard.
Maintenance TROUBLESHOOTI NG 6 6-51 6-56. Hex Inverter ( U221) Check that U221-5 is the sam e as STROBE ZERO and that U221-6 is STROBE ZERO inverted . 6-57. Quad OR G ate (U211) Check U211-6 for 0.2 us pulses, no rmally h igh, in two gro ups of 3 and 15, group widths : 50 and 100 us, group spacin g: 10 ms (in f ast readin g rate).
8842A Instruction M anual 6-52 Table 6-20. Analog Co ntrol Devices DEVICE REF. DES. Relay Buffer U201 Quad Comparat or U305 Quad Analog Swi tch U301 Quad Analog Swi tch U302 Quad Analog Swi tch U303 Q.
Maintenance TROUBLESHOOTI NG 6 6-53 Table 6-21. Analog Co ntrol Logic Stat es t6-21.wmf Next move to U305 -5 and re peat. The slow rea ding ra te gives th e following pat tern at U305-5: 111111 00000 .
8842A Instruction M anual 6-54 If the ins trumen t is not i n the slow re ading rate, it gives the following pa ttern at U30 5-5: 000000 00000 000000 0000000 000 Next move to U305 -7 and re peat. The patte rn at U305-7 will be: 000000 00000 000000 1111111 000 6-61.
Maintenance TROUBLESHOOTI NG 6 6-55 Table 6-22. DC S caling and Track /Hold Supply Voltage s PIN OR DEVICE SUPPLY VOLTAGE PIN OR DEVICE SUPPLY VOLTAGE U301-6 +5V U303-20 +7.5V U301-10 0V U303-11 -8.2V U301-20 +7.5V U304-4 -8.2V U301-11 -5V U304-7 +7.5V U302-6 +5V U305-3 +5V U302-10 0V U305-12 -5.
8842A Instruction M anual 6-56 6-63. Track/Hol d Troubleshooting If a prob lem is su spected in the Trac k/Hold (T /H) circuit, first che ck the power su pply voltages of all activ e compon ents. (See Ta ble 6-22 .) Next, check the T/H output w aveform a t TP103 with an o scillosco pe.
Maintenance TROUBLESHOOTI NG 6 6-57 f6-13.wmf Figure 6-13. T ypical Output Wavef orms for Track/Hol d Circuit (TP103) To test whe ther the O hms Cur rent Source is actual ly bein g sourced out the HI .
8842A Instruction M anual 6-58 If the oh ms functions do not work in a ny range, che ck the suppl ies at U401 (+ /-15V), U404 (+30V and -5V), U402 (+15V, +5V, a nd 0V), and U403 (+15V, +5V, and 0V), and check the -7V r eference a t R416.
Maintenance TROUBLESHOOTI NG 6 6-59 6-66. A/D Converter Troubleshooting If there i s a failu re of the A /D Conver ter, all pow er supply levels sho uld be ch ecked at th e op amps (U102 and U103) and the A/D IC (U101). The A/D Converter has a tota l of seven suppli es: +15V, -15V, +5V, +7.
8842A Instruction M anual 6-60 f6-15.wmf Figure 6-15. W aveforms at U101-2 4 and U101-25 f6-16.wmf Figure 6-16. T ypical Bus Data Line Wa veform The wavefor m at the storage capacitors can often be use d to locat e leakage p roblems. The leakage can be due to co ntamination on the Main PCA or to defec tive switc hes in U101.
Maintenance TROUBLESHOOTI NG 6 6-61 problem be tween the A/D Conve rter and th e In-Guard µ C can cause erroneous o r noisy readings or offsets. S imilar p roblems may be ca used by a fai lure of th e Calib ration Memory (U220 ) or by bad A/D calibrati on constants.
8842A Instruction M anual 6-62 f6-17.wmf Figure 6-17. W aveforms at TP102 for Several Inputs o n 2V DV Range Since power supp ly probl ems can pro duce sympt oms in ma ny differe nt sectio ns of th e instrumen t, the first step i n troublesh ooting any p roblem shou ld usual ly be a quick check of the power sup plies.
Maintenance TROUBLESHOOTI NG 6 6-63 f6-18.wmf Figure 6-18. Cal culating the A/D Readi ng From TP102 Waveform Table 6-23. P ower Supply Voltages LIMITS (in volts) TEST POINT MINIMUM MAXIMU M +5V 4.75 5.25 +7.5V 7.00 7.87 +15V 14.25 15.75 +30V 28.45 31.
8842A Instruction M anual 6-64 The True RMS AC PCA, if in stalled, uses +5V and +/ -15V. If the re is a prob lem with one of tho se supplies, first disc onnect the T rue RMS AC PCA. If the p roblem goe s away, troubleshoo t the Tru e RMS AC PCA using the p rocedure g iven later in this sect ion.
Maintenance TROUBLESHOOTI NG 6 6-65 f6-19.wmf Figure 6-19. Optio n -05 Service Posit ion Table 6-24. Diagno stic Modes SWITCHES A3 A2 A1 CONFIGURATION 1 0 1 Static, odd-port bits = 1, ev en-port bits = 0 1 1 1 Static, odd-port bits = , even-port b its = 1 1 X 0 Dynamic 0 X x Read/Write NOTES: • “x” means switch s etting does not matt er.
8842A Instruction M anual 6-66 Table 6-25. I/O Port Configurations CONFIGURATION CONFIG URATION PORT BIT Static Dynamic Read/Write PORT BIT Static Dynamic Read/Write PO-0 OUT Address P1-0 OUT Data PO-.
Maintenance TROUBLESHOOTI NG 6 6-67 4. Position the True RMS AC PCA vert ically as shown i n Figure 6 -20 and latch i t in place by p ressing th e bottom two nylon latc hes into the speci ally provi ded mounti ng supports on th e chass is.
8842A Instruction M anual 6-68 f6-20.wmf Figure 6-20. Optio n -09 Service Posit ion If the sign al at the input to U8 01A (pin 5 ) is incorrec t, U804 ma y be defect ive, or the switch cod es may be wron g. If the l atter pro blem is s uspecte d, refer t o Table 6-28 an d test the con trol lines to U804 (U804-1, 8, 9, 16).
Maintenance TROUBLESHOOTI NG 6 6-69 Table 6-28. Truth Ta ble for U804 and K2 PIN OR DEVICE RANGE U804-1 U804-8 U804-9 U804-16 K2 2000 mA 10110 200 mV 10010 2 V 11100 2 0 V 01110 200V 11101 700V 01111 NOTE: For U804, lo gic 0 = switch o n. Logic 1 is > 2.
8842A Instruction M anual 6-70 It is s afe to for ce one con trol lin e at a time high (+5V) or low (0V ) to test the ind ividual switches in U808 . (The on re sistance of switches in U808 sh ould be less than 500 Ω ; t he off resis tance shou ld be grea ter than 10 M Ω .
Maintenance INTERNAL C LEANING 6 6-71 6-78. Cleaning After Soldering CAUTION T.M.C. Cleaner and similar products can can attack the ny lon latches and other plastic pieces. f6-21.wmf Figure 6-21. Guard Cro ssing Test Wav eforms If a PCA has bee n soldered, it s hould first be clea ned with SPRAYON T.
8842A Instruction M anual 6-72.
7-1 Chapter 7 List of Replaceable Parts Title Page 7-1. INTRODUCTION ................................................................................ 7-3 7-2. HOW TO OBTAI N PARTS ................................................................. 7-3 7-3.
8842A Instruction M anual 7-2.
List of Replaceable Parts INTRODUCTION 7 7-3 7-1 . INTRODUCTION This section contains an illu strated lis t of repla ceable par ts for the 8842A. Part s are lis ted by assembly ; alphabet ized by ref erence desi gnator. E ach assemb ly is acco mpanied b y an illustra tion showing the loca tion of each pa rt and its refe rence design ator.
8842A Instruction M anual 7-4 7-4 . NEWER INSTRUMENTS Changes and imp rovem ents made to the instru ment a re identi fied by inc rementing the revision l etter marked on the aff ected pca. These ch anges a re documented on a supplement al change/e rrata she et which, wh en applicabl e, is inc luded with th e manual.
List of Replaceable Parts SERVIC E CENTER S 7 7-5 Manual Status Inform ation REF OF OPTION NO. ASSEMBLY FLUKE PART NO. REVISION LEVEL A1 A2 05 09 Main PCA Displ a y PCA IEEE-488 Interface PCA True RMS AC PCA 759365 728873 879267 759266 BE __ D N Table 7-1.
8842A Instruction M anual 7-6 f7-01_1.wmf Figure 7-1. 8842A Digit al Multimeter.
List of Replaceable Parts SERVIC E CENTER S 7 7-7 f7-01_2.wmf Figure 7-1. 8842A Digit al Multimeter (co nt).
8842A Instruction M anual 7-8 f7-01_3.wmf Figure 7-1. 8842A Digit al Multimeter (co nt).
List of Replaceable Parts SERVIC E CENTER S 7 7-9 f7-01_4.wmf Figure 7-1. 8842A Digit al Multimeter (co nt).
8842A Instruction M anual 7-10 Table 7-2. A1 Mai n PCA Reference Design ator Descr ipt ion Fluke S tock No Tot Q ty N otes AR701 REF AMP SE T 759290 1 C101-1 03,C31 1 CAP,P OLYPR,0 .
List of Replaceable Parts SERVIC E CENTER S 7 7-11 Table 7-2. A1 Mai n PCA (cont) Reference Design ator Descr ipt ion Fluke St ock No Tot Q ty Not es J203,J204 CABL E, DISPLAY 684167 2 J602 HE ADER,1 R OW,.1 56CTR ,6 PIN 380378 1 JPR001,JPR002 RES JUMPER,0.
8842A Instruction M anual 7-12 Table 7-2. A1 Mai n PCA (cont) Reference Design ator Descr ipt ion Fluke St ock No Tot Q ty Not es R413 RES ,MF,4. 99M,+- 1%,0 .125W, 100PP M 715060 1 R414 RES ,MF,57 6K,+ -1%,0.1 25W,l 00PP M 344 291 1 R416 RES ,MF,10 0,+-1 % ,0.
List of Replaceable Parts SERVIC E CENTER S 7 7-13 f7-03.wmf Figure 7-2. A1 Main PCA.
8842A Instruction M anual 7-14 Table 7-3. A2 Displa y PCA.
List of Replaceable Parts SERVIC E CENTER S 7 7-15 f7-03.wmf Figure 7-3. A2 Display PCA.
8842A Instruction M anual 7-16 Supply Codes for Manuf acturers supply_1.wmf.
List of Replaceable Parts SERVIC E CENTER S 7 7-17 Supply Codes for Manuf acturers (cont) supply_2.wmf.
8842A Instruction M anual 7-18 service_1.wm f Figure 7-4. Servi ce Centers.
List of Replaceable Parts SERVIC E CENTER S 7 7-19 service_2.wm f Figure 7-4. Servi ce Centers (cont).
8842A Instruction M anual 7-20.
8-1 Chapter 8 Options and Accessories Title Page 8-1. INTRODUCTION .................................................................................. 8-3 8-2. ACCESSORIES ................................................................................
8842A Instruction M anual 8-2.
Options and Accessori es INTRODUCTION 8 8-3 8-1 . INTRODUCTION A number o f options and accesso ries are available wh ich can enhance the 8842A’ s capabilit ies and inc rease opera tor sa fety. The acc essorie s are summa rized in Ta ble 8-1 and described in the fol lowing parag raphs.
8842A Instruction M anual 8-4 8-2 . ACCESSORIES Accessor ies inc lude a variety of rack -mount ing ki ts, cables, tes t leads, and prob es. The accesso ries inclu de instal lation and/or ope rating instru ctions. 8-3. Rack-Mount Kits (Y8834, Y8835 and Y8836) The rack-moun t kits allow the 8842A to be mounted in standard 19-inch rac k panels.
Options and Accessori es ACCESSOR IES 8 8-5 8-10. Current Shunt (80J-10) The 80J-10 cu rrent shun t extends a c or dc cu rrent me asuremen t up to 10A c ontinuous, o r to 20A for on e minu te withou t overhea ting. 8-11. Current Probes (Y8100, Y8101, 80i-400 and 80i-600) The current p robes ex tend the ac a nd dc curren t measure ment range.
8842A Instruction M anual 8-6.
805-1 Chapter 805 Option –05 IEEE-488 Interface Title Page 805-1. INTRODUCTION ................................................................................ 805-3 805-2. CAPABILITIES ...............................................................
8842A Instruction M anual 805-2.
Option –05 IEEE- 488 Inte rface INTRODUCTION 805-3 805-1. INTRODUCTION The IEEE-488 Inte rface tu rns the 8 842A into a fu lly prog rammab le instru ment for u se with the IEEE Standard 488 -1978 interfa ce bus (IEEE-488 bus ). With the IEEE -488 Interface, the 8842A c an beco me part of a n auto mated inst rumenta tion syste m.
8842A Instruction M anual 805-4 3. Disconnec t the ribbon cable fro m the p lastic rear panel inse rt by pu lling the tabs on either s ide of the ribbo n cable conne ctor outwar d. Pull the ribb on cable directly toward th e front pane l (Figu re 805-1C).
Option –05 IEEE- 488 Inte rface LIST OF R EPLAC EA BLE PA RTS 805-5 f805-1_1.wmf Figure 805-1. Insta lling Option -0 5.
8842A Instruction M anual 805-6 f805-1_2.wmf Figure 805-1. Insta lling Option –0 5 (cont).
Option –05 IEEE- 488 Inte rface LIST OF R EPLAC EA BLE PA RTS 805-7 Table 805-1. O ption -05A IEEE-488 Int erface PCA.
8842A Instruction M anual 805-8 f805-2.wmf Figure 805-2. IEEE-488 Interface PCA.
809-1 Chapter 809 Option –09 True RMS AC Title Page 809-1. INTRODUCTION .................................................................................. 809-3 809-2. INSTALLATION ....................................................................
8842A Instruction M anual 809-2.
Option –09 True RMS AC INTRODUCTION 809-3 809-1. INTRODUCTION The True RMS AC option gives the 8842A the ab ility to make ac voltage and current measurem ents. The ac f unctions a re select ed with the f ront panel V AC and mA AC buttons, or by remote co mmands if th e IEEE-488 Int erface op tion is ins talled.
8842A Instruction M anual 809-4 809-3. OPERATING INSTRUCTIONS For operatin g inst ructions, re fer to Section 2. For a c measu rement co nsiderat ions, refer to Section 4. 809-4. MAINTE NANCE All serv ice infor mation re garding Op tion -09 i s contained in Section 6.
Option –09 True RMS AC LIST OF R EPLAC EA BLE PA RTS 809-5 f809-1.wmf Figure 809-1. Insta lling Option -0 9.
8842A Instruction M anual 809-6 Table 809-1. Option -09 True RMS AC PCA t809-1.wmf.
Option –09 True RMS AC LIST OF R EPLAC EA BLE PA RTS 809-7 f809-2.wmf Figure 809-2. True RM S AC PCA.
8842A Instruction M anual 809-8.
9-1 Chapter 9 Schematic Diagrams.
8842A Instruction M anual 9-2.
Schematic Diagrams 9 9-3 f9-01_1.wmf Figure 9-1. Main PCA, DC Sca ling and F/R Switch.
8842A Instruction M anual 9-4 f9-01_2.wmf Figure 9-1. Main PCA, DC Sca ling and F/R Switch (co nt.).
Schematic Diagrams 9 9-5 f9-02_1.wmf Figure 9-2. Main PCA, A/D Con verter.
8842A Instruction M anual 9-6 f9-02_2.wmf Figure 9-2. Main PCA, A/D Con verter (cont.).
Schematic Diagrams 9 9-7 f9-03_1.wmf Figure 9-3. Main PCA, Ohm s Current Source.
8842A Instruction M anual 9-8 f9-03_2.wmf Figure 9-3. Main PCA, Ohm s Current Source (cont.).
Schematic Diagrams 9 9-9 f9-04_1.wmf Figure 9-4. Main PCA, Digi tal.
8842A Instruction M anual 9-10 f9-04_2.wmf Figure 9-4. Main PCA, Digi tal (cont.).
Schematic Diagrams 9 9-11 f9-05_1.wmf Figure 9-5. Main PCA, Power Su pply.
8842A Instruction M anual 9-12 f9-05_2.wmf Figure 9-5. Main PCA, Pow er Supply (cont.).
Schematic Diagrams 9 9-13 f9-06_1.wmf Figure 9-6. Disp lay PCA.
8842A Instruction M anual 9-14 f9-06_2.wmf Figure 9-6. Disp lay PCA (cont.).
Schematic Diagrams 9 9-15 f9-07_1.wmf Figure 9-7. IEEE-488 Int erface PCA.
8842A Instruction M anual 9-16 f9-07_2.wmf Figure 9-7. IEEE-488 Int erface PCA (cont.).
Schematic Diagrams 9 9-17 f9-08_1.wmf Figure 9-8. IEEE-488 Int erface PCA, Option -0 8.
8842A Instruction M anual 9-18 f9-08_2.wmf Figure 9-8 . IEEE-488 Int erface PCA, Option –0 8 (cont.).
Een belangrijk punt na aankoop van elk apparaat Fluke 8842a (of zelfs voordat je het koopt) is om de handleiding te lezen. Dit moeten wij doen vanwege een paar simpele redenen:
Als u nog geen Fluke 8842a heb gekocht dan nu is een goed moment om kennis te maken met de basisgegevens van het product. Eerst kijk dan naar de eerste pagina\'s van de handleiding, die je hierboven vindt. Je moet daar de belangrijkste technische gegevens Fluke 8842a vinden. Op dit manier kan je controleren of het apparaat aan jouw behoeften voldoet. Op de volgende pagina's van de handleiding Fluke 8842a leer je over alle kenmerken van het product en krijg je informatie over de werking. De informatie die je over Fluke 8842a krijgt, zal je zeker helpen om een besluit over de aankoop te nemen.
In een situatie waarin je al een beziter van Fluke 8842a bent, maar toch heb je de instructies niet gelezen, moet je het doen voor de hierboven beschreven redenen. Je zult dan weten of je goed de alle beschikbare functies heb gebruikt, en of je fouten heb gemaakt die het leven van de Fluke 8842a kunnen verkorten.
Maar de belangrijkste taak van de handleiding is om de gebruiker bij het oplossen van problemen te helpen met Fluke 8842a . Bijna altijd, zal je daar het vinden Troubleshooting met de meest voorkomende storingen en defecten #MANUAl# samen met de instructies over hun opplosinge. Zelfs als je zelf niet kan om het probleem op te lossen, zal de instructie je de weg wijzen naar verdere andere procedure, bijv. door contact met de klantenservice of het dichtstbijzijnde servicecentrum.
