Keithley_160B_(1602B)_IM 电路图.pdf

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1、Instruction Manual Model 160B Digital Multimeter Contains Operating and Servicing Information for Model 160B Digital Multimeter and Model 1602B Digital Output 01975, Fourth Printing, December 1977 Keithley Instruments, Inc. Instrument Division Cleveland, Ohio, U.S.A. RadioFans.CN 收音机爱 好者资料库 INSTRUCT

2、ION MANUAL MODEL 1606 DIGITAL MULTIMETER (AND MODEL 16028 DIGITAL OUTPUT) COPYRIGHT 1975, KEITHLEY INSTRUMENTS, INC. FOURTH PRINTING, DECEMBER 1977, CLEVELAND, OHIO, U.S.A. RadioFans.CN 收音机爱 好者资料库 CONTENTS CONTENTS :,OOEL ibOJ SECTION SPECIFICATIONS. . I. GENERAL INFORMATION. . I-l, ,NTRODCT,ON . i-

3、2. FEATURES . . l-3. WARRANTY lNFORHATlON. . l-4. CHANGE NOTlCE . l-5. OPTIONAL MODEL 16028 D,G,TAL oTP T. . 1-6. OPTIONAL MODEL 1688 RECHARGEABLE BATTERY PACK 2. INITIAL PREPARATlON . 2-l. GENERAL . 2-2. INSPECTlON. . Z-1. PREPARATION FOR SE 3. OPERATlNG INSTRUCTIONS . . 3-l. GENERAL 3-2. HOW TO SE

4、LECT POWER. . 3-3. HOW TO MAKE INPUT CONNECTION! 3-4. HOW TO SELECT FUNCTlON 3-5. HOW TO MEASURE VOLTAGE 3-b. HOW TO MEASURE RESISTANCE. 3-7. HOW TO MEASURE CURRENT . 3-8. NOISE CONSIOERATIONS 3-9. THERAL EHFS . . 3-10. MAGNETIC FlELDS . 3-11. AC ELECTRlC FIELDS . 3-12. SHIELDING. . - . . * . I . .

5、. 3-13. HOW TO SE THE ANALOG OUTPUT 3-14. HOW TO USE MODEL 1608 OFF-GROUND . . 3-15. HOW TO USE MODEL 16028 DlGlTAL OUTPUT. 3-16. HOW TO RACK MOUNT THE MODEL 1608 4 THEORY OF OPERATION. . . . . . . . . : : 4-l. GENERAL . 4-2. ANALOG AMPLIFIER ClRC,TRY : : : : : : 4-3. ANALOG-TO-DIGITAL CONVERTER. .

6、4-4. POWER SUPPLY . . . . 4-S. MODEL 16028 DIGITAL OVTPUT . : : 5. ACCESSORIES. . MODEL 1601 AC DC PROBE MODEL 1688A RECHARGEABLE BATTERY bAiK: : MODEL 1683 UNIVERSAL TEST LEA0 KIT MODEL 1600 HIGH VOLTAGE PROBE. MODEL 1682 RF PROBE. . MODEL 1609 CALlBRATlON COVER . . MODEL 1681 CLIP-ON TEST LEAD SET

7、 6. AINTENANCE. . 6-1. GENERAL. 6-2. REQUIRED TEST EQUIPHENT. t 6-3. PERFORMANCE VERIFICATION . b-4. ADJUSTMENT/CALIBRATION PROCEDURE 7. REPLACEABLE PARTS. . 7-l. GENERAL. . 7-2. ORDERING INFORMATION . . . . . . ., . 7-3. SCHEMATlCS ii . . . . . . . . . PAGE I I I I I k 2 6 8 8 8 9 IO Ii 12 12 12 12

8、 12 14 14 16 22 23 23 23 26 ,P 32 32 : : 34 2 : 35 37 45 45 15 45 RadioFans.CN 收音机爱 好者资料库 ILLUSTRATIONS rzg. NO. IIcLe 1 “fme”sio”al Data. -_-_-_-_ 2 Tilt Bail Positions. - 3 *pant panel. - 4 *ottcm View Showing Line Cord. - 5 Rear View Showing Line Switches. -_-_-_ 6 Mode11688A Rechargeable Pack. -

9、 Batrery 7 Exploded View of Model 160B/1688A.- 8 Installatio of Pack. - Battery 9 Battery Test Location. -_-_- 10 Front Panel Controls. -_- 11 Imcarion of Protection Fuse. _-_-_-_ 12 Voleage Measurements sing Model 1601 AC/DC Probe. - 13 Current Measurements Using Made1 1651 Shunt. - 14 Floating ope

10、ration. -_-_-_-_ 15 Model 16028 ,+ 9 11 13 13 14 15 16 17 18 * 22 23 25 25 25 27 28 28 29 38 40 41 44 44 54 55 56 57 58 59 60 61 63 64 0976 SPECIFICATIONS MODEL 1608 I 10.7 (27: 5 i I DIMENSIONS IN INCHES (MM) I FIGURE 1. Dimensional Data. 1174 SPECIFICATIONS Calibrated at 25” *ST war,mte* to, 1 yea

11、r AS A DC VOLTMETER AS AN OHMMETER Liz2 m NORMAL BENCH POSITION LEVEL POSITION - TILTEAIL AT FRONT J rounded receptacles (see Figure 4 for 1% configura- tion,. the permanently installed line cord is stored by wrapping the card around the base of the istr- ment as shown in Figure 4. 1. wow to Set Lin

12、e Switches. The Made1 1608 has two rear panel Line Switches which enable selection of line voltages over ranges from x0-llO, 105125v, 195-235, or 210-250. TO operate from line power. determine the appropriate line voltage range to be used and set the Line Swirches as fallows: TABLE 2-1. Summary of L

13、ine Switch Settings. I I I Jo-110” I 1 LOW. 117 105-125” NORM, 117 I 195-235” LO, 234 210-250 NORM. 234 For example, if the line voltage ea be used is approximately 115 volts, select NORM and 117 which permits B range of operarion from 105 to 125v. hfter line Switches are set, connect the line cord

14、and set the Power Switch to LINE. 2. ,.ine Fuse Requirements. The Model 1608 uses VO line fuses to protect the line-operated power SWPlY. ne fuse types are l/8 ampere, MB, slow- blow. Replace with Keithley Part No. F-20. 3. How to Replace Fuses in Model 1688A. The !Jodel, 1688H uses 1 ampere fuses t

15、o protect the power supply regulators in case of malfunction. Fuses F203 and F204 are plug-in types and are lo- cated on pc board PC-349 as shown in Figure 8. Keplace with 1 ampere, 3AB, slo-blo, Keithley Part NO. FU-28. MODEL 160B b. Row to operate From Battery Power. TO operate the Model 16OB from

16、 batteries, the Model 1688A Re- chargeable battery Pack must be installed. The Model 1688A can be either field or factory installed. (The batteries in the Model 1688A may need recharging be- fare their first usage to power the Model 1600.) NOTE The Model 1688A Rechargeable Battery Pack can be insral

17、led within the Model 1608 chassis at any time. However, if the Model 16028 Digital Output is already installed, the Model 1688A cannot be used simultaneously. 1. HOW to Install Model 168% Rechargeable Bat- tery Pack. The batteries furnished with the Model 1688A come already installed in the battery

18、pack. the battery pack includes 7 rechargeable C cells (1.2, 3 AMP HR) and 1 rechargeable pack (16.8V). If baeeeries need to be replaced or re-installed, be certain to observe the proper polarity of indi- vidual cells as shown in Figure 6. To install the Model 1688A Battery Pack, turn the instrument

19、 over so that the bottom cover faces up. Loosen four slotted screws on the batrom cover as shown in Figure 4. (A chisel-blade screwdriver is requires to loosen the slotted screws.) Turn over the in- strument with tap cover facing up, taking care to hold the top and bottom covers together. Carefully

20、remove the top cover to gain access fo the printed circuit board. (Two ires that connect to the Analog Oufput must be disconnected at the PC board before the top cover can be set aside.) Check to see that the four insulating spacers are in yasi- tion on the printed circuit board. Place the Model 168

21、8A Battery Pack in position an the spacers with the cable oriented as sham in Figure 8. Plug the 4-wire Conneceor (5205) into the mating receptacle (P205) taking care to orient the connector as shown in Figure 8. After the Battery Pack is in- stalled. replace the top cover. Turn over the in- strumen

22、; wiih bottom co four positions are direct-read- ing in voles (VI. Decimal point is selected by the Kan,qe Switch. Polarity is automatically displayed. If the input signal exceeds twice full range, the display blanks (3 least significant digits) to in- dicate an “overran Max. Display 1999 * 199.9 19

23、.99 1.999 199.9 19.99 1.999 d *Maximum allowable input is 1200” dc plus peak ac even though display can be read beyond 1.200”. 1174 b. How to Determine Accuracy. The xodel 16011 nc- curacy is iO.I% of readina f 1 dirit. For enarno1e. a display reading of 1.005 volt dc will have a” ,a,- certainty of

24、10.1% f 1 digit or r.002 volts. The in- put resisrance in the dc m”de is 10 o,c“,cs. !,eai- urements from relatively high source resistnnccs could cause an additional reading error. The dln”“,:i of error due to loading can bc determined by rhc following relatiansbip: % error = 100 x RS i (R, + 10) w

25、here R, = Source resistance in ohms For example, a so”rcc resistance “f 10,000 ohms Viii result in a loading error of approximately 0.1% ai reading. The input current of the 1608 Cal” also cause reading errors on the nlOSL sensitive vo1cage ranges when high source resistances are pre- sent. For exam

26、ple, an input CUrrent of lOpA and a so”rce resistvnce of MI! produce a” error voltage of loll”. c. Maximum Allowable Input. The maximum L”P”L to the Model 1608 is 1200” dc + peak ac. On lrn”, lOn,V, and lOOn,” ranges, the maximum conti”uox,s input is 6OOV (12OOV momentary) dc + peak ac. ,hc ?,odel ,

27、SO” can display dc voltages greater tba” r120O” but dnm- age to the input is possible. 0 OPERATING INSTR”CTIONS MODEL L6OB IMPORTANT The Model 1608 provides ac rejection (NMRR) of greater than 60 dB on the highesf range. However, a large ac signal superimposed on a dc level could cause damage if the

28、 input CO the Model 160 exceeds 1200 volts dc + peak UC. d. How to Zero the Display. To accurately zero the instrument, place a low-thermal short (such as a piece Of clean copper wire) across the input rermin- als, set Lhe Range Switch to the lm range, and ad- just the front panel Zero conerol for a

29、 flashing i sign at the display. The display should then read t.OOO, with some flicker of the least significant digit due to noise and A-D converter uncertainfy. Once the zero has been set accurately, there should be little reason to rezero the instrumenf again soon when making measurements on the 1

30、01 through 1000 ranges. The time stability of rhe zero setring is excellent, and in applications requiring continuous operation of the Model 160B, the zero setting will hold for months. The front panel Zero control is convenienf when making measurements on fhe 11 Range. A test set-up and cables when

31、 connected to the 160B may cause offset voltages because of thermoelectric effects (see section 3-9). These offset voltages might be only a few microvolts or several tens of microvolts. In such situations, the Zero control can be used to buck out any initial offsefs. I. thermal cabling and connectio

32、ns should be used when- ever possible. The instrument zero can also be check ed, and adjusted, by shorring the input on any range (voltage, current, or resistance). me zero c*t*01 will have varying effects on the differenr ranges depending on the sensitivity of the input amplifier, but the zero cont

33、rol can be used in this manner. Again, it should be emphasized, that for most meas- remene with the Model 160B, the Zero control can be set once and then left untouched. (See also ?ec- tion 3-6c LO Ohms Zeroing). NOTE With the input open 0 the lm Range, the Model 1603 display may show a reading as h

34、igh as i.100. This 19 equ*va1ent to an offset currene of lo.opA. If the display shows a reading grearer than t.100, then the internal potentiometer, R121, should be readjusted. Typically, ehe offset cur- rent will be less than 5p. e. 80 to se Model 1601 AC/DC Probe. TO make ac measuremenfs, connect

35、the Model 1601 accessory K/DC Probe to the Model 1608 inpur terminals. Set the Range to desired voltage range. Set switch on probe to AC. se the probe tip plus ground clip to make connections to circuit under eesc. see section 5 for complete specifications. 1-6. HOW TO MEASURE RESISTANCE. The Model

36、1608 measures resistance in 10 ranges: lsr, 1on, 10011, Ikn, IOkions are direct-reading in ohms (n): three positions are direct-reading in kilohms (kn); four positions are direct-reading in megohms (MQ) Decimal point is selected by Range Switch. If the input signal exceeds twice full range, the disp

37、lay blanks to indicate an overra however, the input amplifier of the Model l6OB uses a modulator to convert DC signals LO AC signals before amplification. The drive frequency of this modulator is 220 HZ nominally, f approx. 5%. Interfering AC signals with frequencies equal to the modulator drive fre

38、quency, or mu1tipl.e fhereof, will appear 8.3 modulated DC, and produce large DC errors. 3-12. SHIELDING. a. Electric Fields. Shielding is usually necea- 8arv when the insrrument is in the eresence of verv live measuremen;s are being made. The shields of rhe measurement cir- cuit and leads should be

39、 connecee* together to ground at only one point. This provides a tree configura- tion, which minimizes ground loops. b. Magnetic Fields. Magnetic shielding 19 useful where very large magnetic fields are present. Shield- ing, which is available in ehe form of plates, foil or cables, can be used to sh

40、ield the measuring cir- cuit, the lead wires, or the instrument itself. C. Other Considerations. 1. Voltmeter Measurements. Use shielded input leads when source resiseances are greater than 1 kilohm or when long input cables are used. 2. Current Measurements. On the mA and PA cur- rent ranges, no sp

41、ecial shielding precautions need be taken. However, an the 100 and 10 nanoampcre ranges, shielded input leads are recommended. 3. llesiatance Measurements. Shielding of input leads and source are recommended for measurements on the 10 megohm through 1000 megohm ranges to pre- vent errOneOS readings.

42、 12 1174 FIGURE 12. Voltage Measurements Using Model 1601 AC/DC Probe. CURRENT TERMINALS VOLTAGE TERMINALS VOLTAGE LEADS FURNISHED ;* 1 1174 OPERATING lNSTRCTlONS MODEL 1608 I i+ - EXTERNAL E% DC MODEL 1608 TYPICAL I lOn ISOLATION CASE 8 RESISTANCE GROUND FIGURE 14. Floating Operation 3-13. HOW TO U

43、SE THE ANALOC OUTPUT. The Model 16OB has an analog output of il volt at full-range (non- inverting) at up to 1 milliampere (2mA at 2 volts) for recording or monitoring purposes. Also, the analog output enables the Model 1608 to be used as a la-noise, low drift DC amplifier. TABLE 3-5. hi at liNALOG

44、OUTPUT across lk = I x lkn = 10-a x 103 = lOllDC Range 1 In 1.0 rn 100 In Gain x1000 x100 x10 Full Range OUtpUt 1 1 1 For off-ground operarim, the analog output should be connected only to equipment capable of operating off-ground also. The low side of the analog output is at the same poeential as t

45、he LO input terminal of the Model 160. 3-14. HOW TO USE MODEL 1608 OFF-GROUND. The LO terminal can be operated off ground at potentials Of up tLl 11200. Isolation franI ehe LO terminal to power line ground is specified at lOOOMn, or 100 (shunted by 300). Ty,ically, the isolation resis- tance from I.

46、0 to GNE is two decades greater than log!? (lOO). Because of this excellent isolation, operating the Model 1608 off ground results in very 1.itr1e loading (from LO to GNU) of a floating source. AC 1000 above ground, the Model 1608 will require, typically, only 1Onh from the source. The excellent i.s

47、olation also accounts for the high common-mode re- 14 The isolation capacitance from LO to GNC is impor- tant when AC common-mode signals are present. in the Model 1608, rhis capacitance is specified at 300 pF maximum. At a frequency of 60 HZ, 300 picofarads has a reactance of approximately 10Mli. With the HI terminal driven and a source impedance of lkll, R 1OOOV p-p, 60 Hz, common-mode signal will produce a voltage of only loom p-p across the Model 1608 in- put terminals. This lOOmV p-p signal will be lurtbcr rejected by the input amplifier and A-1) converrer SC that the to