KEI 238 Service 电路图.pdf

《KEI 238 Service 电路图.pdf》由会员分享，可在线阅读，更多相关《KEI 238 Service 电路图.pdf（88页珍藏版）》请在收音机爱好者资料库上搜索。

1、Model 238 High Current Source Measure Unit Service Manual Contains Servicing Information RadioFans.CN 收音机爱 好者资料库 WARRANTY Keithley Instruments, Inc. warrants this product to be free from defects in material and workmanship for a period of 1 year from date of shipment. Keithley Instruments, Inc. warr

2、ants the following items for 90 days from the date of shipment: probes, cables, rechargeable batteries, diskettes, and documentation. During the warranty period, we will, at our option, either repair or replace any product that proves to be defective. To exercise this warranty, write or call your lo

3、cal Keithley representative, or contact Keithley headquarters in Cleveland, Ohio. You will be given prompt assistance and return instructions. Send the product, transportation prepaid, to the indicated service facility. Repairs will be made and the product returned, transportation prepaid. Repaired

4、or replaced products are warranted for the balance of the original warranty period, or at least 90 days. LIMITATION OF WARRANTY This warranty does not apply to defects resulting from product modification without Keithleys express written consent, or misuse of any product or part. This warranty also

5、does not apply to fuses, software, non-rechargeable batteries, damage from battery leakage, or problems arising from normal wear or failure to follow instructions. THIS WARRANTY IS IN LIEU OF ALL OTHER WARRANTIES, EXPRESSED OR IMPLIED, INCLUDING ANY IMPLIED WARRANTY OF MERCHANTABILITY OR FITNESS FOR

6、 A PARTICULAR USE. THE REMEDIES PRO- VIDED HEREIN ARE BUYERS SOLE AND EXCLUSIVE REMEDIES. NEITHER KEITHLEY INSTRUMENTS, INC. NOR ANY OF ITS EMPLOYEES SHALL BE LIABLE FOR ANY DIRECT, INDIRECT, SPECIAL, INCIDENT OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OF ITS INSTRUMENTS AND SOFTWARE EVEN IF KE

7、ITHLEY INSTRUMENTS, INC., HAS BEEN ADVISED IN ADVANCE OF THE POSSIBILITY OF SUCH DAMAGES. SUCH EXCLUDED DAMAGES SHALL INCLUDE, BUT ARE NOT LIM- ITED TO: COSTS OF REMOVAL AND INSTALLATION, LOSSES SUSTAINED AS THE RESULT OF INJURY TO ANY PERSON. OR DAMAGE To PROPERTY. KeithIey Instruments, Inc. ? 2877

8、5 Aurora Road ? Cleveland, OH 44139 ? 440-248-0400 ? Fax: 44248-6168 ? http:N BELGIUM: CHINA: FRANCE: GERMANY: GREAT BRITAIN: INDIA: ITALY: NETHERLANDS: SWITZERLAND: TAIWAN: Kelthley Instruments B.V. Bergensesreenweg 709 ? B-1600 Sint-Pieters-L.eeuw ? OX363 00 40 ? Fax: 02/363 00 64 KeithIey Instrum

9、ents China Yunn Chen Xin Building, Rmm 7M ? 12Yumin Road, Dewai, Madian * Beijing loo029 ? 8610.62022886 ? Fax: 86162UZ2892 Keitbley Instruments Sad B.P. 60 ? 3, all fixed range selectionusing rotary dial and SELECT keys (DC function). Fully programmable in SWEEP function. Measure: Auto or fixed ran

10、ge. Fixed range selection made by choice of COMPLIANCE value. FILTER: Takes n measurements, calculates and outputs average (n = 2,4, 8,16, or 32, selectable). SUPPRESS: Subtracts displayed measurement from subsequent readings. MENU: DC Measurement Delay, Default Delay On/Off, Local/Remote Sense, 50/

11、6OHz, IEEE Address, Self Tests. DATA ENTRY: Numeric keypad or detented rotary dial. TRIGGER: Input and Output: Set for any phrise of SOURCE-DELAY-MEASURE sequence or trigger output at end of sweep. Origin: Internal, External (including front panel MANUAL TRIGGER button), IEEE-488 bus (TALK, GET, “X9

12、. MEMORY: Stores one full sweep (up to 1000 points) of source, delay, and measure values, elapsed times, and sweep parameters. Lithium battery backup. INTERLOCK: Use with test fixture or external switch. Normally closed; open puts instrument in standby. VOLTAGE SOURCE V MEASURE V RANGE ACCURACY ACCU

13、RACY (Max. STEP (1 Year, RESOLUTION (1 Year, Value) SIZE 18=-WC) 4-Diait S-Diait w-28C) Model 238 Source Measure Unit Specifications f1.5000V 100 FV *(0X133% + 8OOpV 100 PV 10 PV f(O.OZS% + 4501. + 1,/I, x 600V)z + I,/I,l x 6cQw f15.000V 1mV *(0.033%+ 2.7mV) 1mV 100 PV f(0.025%+ 13mV) f110.00V 1OmV

14、f(0.033%+ 24mV) 1OmV 1mV f(0.025%+ 1OmV) I, = Oulput current I, = Full scale on selected current range I Spe Current Ranging . 3-11 Analog Switching; Current Ranging . 3-11 Analog Switching; Feedback . 3-12 Analog Switching; Sensing . 3-12 Analog Switching; A/D Multiplexing . 3-12 DigitalCircuitryCh

15、ecks . 3-13 DisplayCircuitryChecks . 3-14 SECTION 4 - Principles of Operation Table 4-l VoltsRangeRelays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-8 + SECTION 1 Performance Verification 1.1 INTRODUCTION The procedu

16、res outlined in this section may be used to verify that the instrument is operating within the limits stated in the specifications at the front of this manual. Performance verification may be performed when the in- strument is first received to ensure that no damage or n +(0.0625% + 10 counts) 2OOnA

17、 range; +(0.005% + 2 counts) 2OV-1OOOV ranges; +(0.007% + 1 count) 2OOR-200WZ ranges; +(0.007% + 2 counts) 200-2mA ranges; +(1.6% + 66 counts) 20 A range; -0.6% + 7 counts) 2 obl pA range; k +(0.25% + 5 counts) 2OnA range; +(0.25% + 1 count) 20014 range; +(0.15% + 4 counts) 2OpA range; +0.002% Curre

18、nt Calibrator lOOmA-1A ranges; +0.025% 1OOQ Resistor 1161 Resistor +O.l%, +lBOppm 9pA, 90/. fl70ppm 9OmA; k230ppm 0.9A; f625ppm Measure DC Current 250ppm rdg +5OOnA 1 s.1 Equipment Characterization In order to verify the I, lo, lOOl.tA, 1mA and 1Om.A source and measure ranges of the Model 238, the 0

19、.9p.A, 9p.A, 9Ol. 4. Subtract the two voltage measurements from each j TIME at LINECYCLE PERIOD, source at other Verify that the absolute value of the result is _ -* _ +l.OOOOuA, and compliance at 1V on the 1.5V range. l.ZUmV I v+1fl- V-IU I Igo + 6nA 1 = -IgoltA + I: (0.00035 IN,A + 6nA I= ti + +:I

20、_: PA -: /.LA +9O.OOOpA 831.4 -9O.OOOp4 +83nA In-IA +Io.g, + (0.00035) Io.g, + 60nA = +- . _ _ _ _ _ mA -Io.sm+ (0.00035) IO.- + 6OnA = +- . _ _ _ _ _ mA +0.9OOOOmA +8OOnA -. _ _ mA -. _ _ mA -0.90000mA800nA lOIlL +Igti + (0.00038) +(0.0625% + 10 counts) 200nA range; +(0.035% + 10 counts) 2OOmV, 2V

21、ranges; +(0.005% + 2 counts) 2OV-1OOOV ranges; +(0.007% + 1 count) 200! +(0.007% + 2 counts) Test Fixture 2OOfl,2mA ranges; +(0.09% + 10 counts) 8006 - R-249-100 lOOn Resistor R-263-l k 1m Resistor LO.1 %, *20ppm/“C 1OOwZ Resistor +0.025% 2-1 SECTION 2 + Calibration Table 2-2 Specifications for Alte

22、rnate Equipment Instrument Type DMM Source DC Current Required Specifications Same as Keithley 193A (see Table l-1) 0.9nA, 9nA, 9On4, Same as Keithley 263 (see Table 2-l) 0.9pA; +180ppm 9pA, 90pA, 9001.(A, 9mA; +170ppm 9OmA; +230ppm 0.9mA; k625ppm Turn on the Model 238 and allow it to warm up for at

23、 least one hour before performing the calibration procedures. If the instrument has been subjected to extremes of tem- perature or humidity, allow at least one additional hour for the internal temperature to stabilize. Typically, it takes one additional hour to stabilize a unit that is 10C (18OF) ou

24、tside the specified temperature range. 2.5 CAL LOCK WARNING A switch (CAL LOCK), accessible through the rear panel with a thin shaft screwdriver (see Figure 2-0, is used to prevent inadvertent calibration of the Model 238. CAL LOCK is a two position (in and out) pushbutton switch. With the CAL LOCK

25、switch in the locked “out” position, storage of calibration constants in nonvolatile memory cannot take place. Temporary calibration values can be entered and used with CAL LOCK in the “out” position. However, when power is turned off, the newly entered calibration constants will be lost. Model 238

26、+ Rear Panel L Calibration Switch Figure 2-1 Calibration Switch (Cal Lock) When calibration is performed with CAL LOCK in the unlocked “in” position, calibration constants will be stored in nonvolatile memory when the C59 command is sent over the bus. 2.6 CALIBRATION PROCEDURES The step-by-step proc

27、edures for calibrating the Model 238 are provided here. Calibration is divided into three separate procedures that are independent of one another. That is, any or all (in any order) of the three procedures can be performed. The three procedures include; voltage calibration (paragraph 2.6.2), 1OOmA a

28、nd 1A calibration (paragraph 2.6.31, and low current ranges calibration (paragraph 2.6.4). Calibration is performed using the “C” command over the IEEE-488 bus. Details concerning the use of the “C” command and other commands are contained in Section 3 of the Model 238 Operators Manual. Lethal volta

29、ge (up to 1OOV) will be connected to the Model8006 test fixture. To avoid a pos- sible shock hazard, the safety interlock cir- cuit must be connected to the Model 238. Connect the test fixture screw to safety earth ground us- ing #18 AWG wire minimum before use. Turn off all power before connecting

30、or disconnecting wires or ca- bles. Also, keep in mind that GUARD is always enabled. Thus, a lethal voltage on OUTPUT HI is also present on the two GUARD terminals of the Model 238. 2.6.1 Equipment Characterization In order to calibrate the lpA, lOpA, lOOpA, 1mA and 1OmA source and measure ranges of

31、 the Model 238, the 0.9pA, 9pA, 9Oj.tA, 0.9mA and 9mA outputs of the Model 263 are characterized. 1. Connect the Model 263 source, Model 193A DMM and Model 8006 test fixture as shown in Figure 2-2. Install the 1OOwZ resistor (in Table 2-l) in the AXIAL KELVIN CLIPS test socket of the test fixture. 2

32、-2 + + SECTION 2 Calibration Banana Plug Cables (5) AI 7078-TRX- I I Model 193A DMM Warning: Connect to Safety Earth Ground Signal Panel Component Test Module Cable Model 263 Source Installed A. Connections Model 8006 Test Fixture 263 Source (Source I) n VONS OUTPUT 8 Source HI sense R I -a “7 193A

33、DMM COMMON (Measure “in” for permanent calibration, or “out” for temporary calibration. c59x If the switch is in the “out” position, the message “TEMPORARY CAL” will be briefly displayed to in- dicate that newly entered cal constants will be lost when the Model 238 is turned off. Permanent cali- bra

34、tion can still be done by setting the calibration switch to the “in” position, and sending COX and C59X over the bus in that order. After sending the C59X command, the Model 238 will go into standby. 2-7 SEC7ION 2 Calibrahon + 2.6.3 IOOmA and 1A Ranges Calibration To calibrate the lOOmA and 1A range

35、s, connect the circuit shown in Figure 2-4. 100mA Range Calibration Perform the following steps to calibrate the 1OOmA source and measure range: 1. Set the Model 193A to the 200 (DC) range. 2. Place theMode 238 in operate. The calibration mode cannot be entered with the Model 238 in standby. 3. Over

36、 the IEEE-488 bus, send the following command to enter the calibration mode: cox Note: All other calibration commands (Cl through C59) will be ignored unless the CO command is first sent over the bus. 4. Send the following command to source +OmA on the lOOmA range: c34X 5. Set the Model 343A to outp

37、ut OV and place the Model 2500E on the lOO range. 6. From the display of the Model 193A, record the off- set current (I+o “in” for permanent calibration, or “out” for temporary calibration. c59x If the switch is in the “out” position, the message “TEMPORARY CAL” will be briefly displayed to in- dica

38、te that newly entered cal constants will be lost when the Model 238 is turned off. Permanent cali- bration can still be done by setting the calibration switch to the “in” position, and sending COX and C59X over the bus in that order. After sending the C59X command, the Model 238 will go into standby

39、. 2-8 + 6-Z + 07 mdino 11ndlno (I =JnoS) 8EZ e-e ? ? ? ? (I -Jnos) JoleJq!le3 ? ? eoJnog . + JWJq!lW 3a VEPE I 8EZ WKI - Xtll-8LOL aJnw!zl t-1 9008 J SECTION 2 Calibration + 1A Range Calibration Perform the following steps to calibrate the 1A source and measure range: 1. Set the Model 193A to the 2m

40、A (DC) range. 2. Place the Model 238 in operate. The calibration mode cannot be entered with the Model 238 in standby. 3. Over the IEEE-488 bus, send the following command to enter the calibration mode: cox Note: All other calibration commands (Cl through C59) will be ignored unless the CO command i

41、s first sent over the bus. 4. Send the following command to source +OmA on the 1A range: C26X 5. Set the Model 343A to OV and place the Model 2500E on the lOO/.tA range. 6. From the display of the Model 193A, record the off- Set current (I+OA): I+OA = 7. Send the current reading (I+OA) over the bus

42、with the C27 command as follows to calibrate offset for the +lA source and measure range: C27,1+oX 8. Send the following command to source +0.9A: C28X 9. Set the calibration source to -0.9A on the 1A range 10. From the display of the Model 193A, record the cur- rent (1193A): I 193A = 11. Calculate t

43、he actual current (1+0.9A) using the follow- ing calculation: h9A = 0.9A + 1193A = A 12. Send the calculated current reading h.9A) over the bus with the C29 command as follows to calibrate gain for the +lA source and measure range: c%,I+O.SAx 13. Send the following command to source -0A on the 1A ra

44、nge: c3ox 14. 15. Set the Model 343A to OV and place the Model 2500E on the lOO range. From the display of the Model 193A, record the off- Set current (I-OA): I-OA = 16. Send the current reading (I-OA) over the bus with the C31 command as follows to calibrate offset for the -lA source and measure ra

45、nge: C31,IaAX 17. Send the following command to source -0.9A: c32X 18. 19. Set the calibration source to +0.9A on the 1A range. From the display of the Model 193A, record the cur- rent (1493A): I-193A = 20. 21. 22. CahdatetheaCtUalCLUTent (1.0.9A) using the follow- ing calculation: I-0.9A = -0.9A +

46、I-193A = Send the calculated reading (h9A) over the bus with the C33 command as follows to calibrate gain for the -lA source and measure range: c33,1-o.d Send the following command over the bus to exit calibration: Note: Check that the CAL LOCK switch is in the de- sired position; “in” for permanent

47、 calibration, or “out” for temporary calibration. c59x If the switch is in the “out” position, the message “TEMPORARY CAL” will be briefly displayed to in- dicate that newly entered cal constants will be lost when the Model 238 is turned off. Permanent cali- bration can still be done by setting the calibration switch to the “in” position, and sending COX and C59X over the bus in that order. After sending the C59X command, the Model 238 will go into standby. 2-10 + SECTION 2 Calibration 2.6.4 Low Current Ranges Calibration (lnA-10mA) Connect the characterized Model 263 calibrator to