KEI197A_901_01C 电路图.pdf

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1、Model 197A Autoranging Microvolt DMM Users Manual MY MY A GREATER MEASURE:OF CONFIDENCE A GREATER MEASURE:OF CONFIDENCE 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 I year from date of shipment.

2、Keithley Instruments, Inc. warrants 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

3、warranty, write or call your local 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, tr

4、ansportation prepaid. Repaired 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 produ

5、ct or part. This warranty also 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

6、 MERCHANTABILITY OR FITNESS FOR 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, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OF ITS IN

7、STRUMENTS AND SOFTWARE EVEN IF KEITHLEY 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.

8、Keithley Instruments, Inc. * 28775 Aurora Road * Cleveland, OH 44 I39 * 440-248-0400 * Fax: 440-248-6 I68 * RadioFans.CN 收音机爱 好者资料库 Model 197AAutoranging Microvolt DMM Users Manual 01990, Keithley Instruments, Inc. All rights reserved. Cleveland, Ohio, U.S.A. Third Printing, February 2001 Document N

9、umber: 197A-901.01 Rev. C RadioFans.CN 收音机爱 好者资料库 SAFETY PRECAUTIONS The following safety precautions should be observed before operating the Model 197A. This instrument is intended for use by qualified personnel who recognize shock hazards and are familiar with the safety precautions required to av

10、oid possible injury. Read over the manual carefully before operating this instrument. Exercise extreme caution when a shock hazard is present at the instruments input. The American National Standards Institute (ANSI) states that a shock hazard exists when voltage levels greater than 30V ms or 424V p

11、eak are present. A good safety practice is to expect that a hazardous voltage is present in any unknown circuit before measuring. Inspect the test leads for possible wear, cracks or breaks before each use. If any defects are found, replace the test leads. For optimum safety do not touch the test lea

12、ds or the instrument while power is applied to the circuit under test. Turn the power off and discharge all capacitors, before connecting or disconnecting the instrument. Do not touch any object which could provide a current path to the cmnmon side of the circuit under test or power line (earth) gro

13、und. Always make measurements with dry hands while standing on a dry, insulated surface, capable of with- standing the voltage being measured. Exercise extreme safety when testing high energy power circuits (AC line or mains, etc). Refer to High Energy Circuit Safety Precautions found in paragraph 2

14、.2. Do not exceed the instruments maximum allowable input as defined in the specifications and operation section. Instrumentation and accessories should not be connected to humans. Safety Precautions The following safety precautions should be observed before using this product and any associated ins

15、trumentation. Although some in- struments and accessories would normally be used with non-haz- ardous voltages, there are situations whcrc hazardous conditions may be present. This product is intended for use by qualified personnel who recog- nize shock hazards and are familiar with the safety preca

16、utions re- quired to avoid possible injury. Read the operating information cweiully beiorc using the product. The types of product osers arc: Responsible body is the individual or group responsible for the use and maintenance oi equipment, for ensuring that the equipment is operated within its speci

17、fications and operating limits, and ior en- suring that operators are adequately trained. Operators use the product ior its intended function. They most be trained in electrical safety procedures and proper use of the instn- ment. They most bc protected from electric shock and contact with hazardous

18、 live circuits. Maintenance personnel perform routine procedures on the product to keep it operating, ior example, setting the line voltage or replac- ing consumable materials. Maintenance procedures are described in the manual. The procedures explicitly state if the operator may per- form them. Oth

19、erwise, they should be performed only by service pCIS”tttEl. Service personnel arc trained to work on live circuits, and perform safe installations and repairs of products. Only properly trained ser- vice personnel may perform installation and service procedures. Keitbley products are designed ior “

20、se with electrical signals that are rated Installation Category I and Installation Category II, as de- scribed in the International Electratechnical Commission (IEC!) Standard IEC 60664. Most measurement, conaol, and data I/O sig- nals are Installation Category I and most not be directly connected t

21、o mains voltage or to voltage sowces with high transientovcr-volt- ages. Installation Category II connections require protection for high transient over-voltages often associated with local AC mains connections. The user should assome all measurement, control, and data I/O connections zwe for connec

22、tion to Category 1 sources un- less otherwise marked or described in the Manual. Exercise extreme caution when a shock hazard is present. Lethal voltage may be present on cable connector jacks or test fixtures. The American National Standards Institute (ANSI) states that a shock hazard exists when v

23、oltage levels greater than 30V RMS, 42.4V peak, or 60VDC are present. A good safety practice is to expect that hazardous voltage is present in any unknown circuit before measuring. Users oi this product must be protected from electric shock at all times. The responsible body must ensure that users a

24、re prevented access and/or insulated from every connection point. In some cases, connections must be exposed to potential human contact. Product users in these circumstances must be trained to protect themselves from the risk of electric shock. If the circuit is capable of operating at or above 1000

25、 volts, no conductive part of the circuit may be exposed. Do not connect switching cards directly to unlimited power circtdts. They are intended to be used with impedance limited sources. NEVER connect switching cards directly to AC mains. When con- necting sources to switching cards, install protec

26、tive devices to lim- it fault current and voltage to the card. Before operating an instrument, make sore the line cord is connect- ed to a properly grounded power receptacle. Inspect the connecting cables, test leads, and jumpers for possible wear, cracks, or breaks before each use. When installing

27、equipment where access to the main power cord is restricted, such as rack mounting, a separate main input power dis- connect device must be provided, in close proximity to the equip- ment and within easy reach of the operator. For maximum safety, do not touch the product, test cables, or any other i

28、nstruments while power is applied to the circuit under test. ALWAYS remove power from the entire test system and discharge any capacitors before: connecting or disconnecting cables or jump- ers, installing or removing switching cards, or making internal changes, such as installing or removing jumper

29、s. Do not touch any object that could provide a current path to the com- mon side oitbe circuit under test or power line (earth) ground. Always make meauremem with dry hands while standing on a dry, insulated surface capable of withstanding the voltage being measured. The instrument and accessories

30、must be used in accordance with its specifications and operating instructions or the safety of the equip- ment may be impaired. Do not exceed the maximum signal levels of the instruments and ac- cessories, as defined in the specifications and operating inform% lion, and as shown on the instrument or

31、 test fixture panels, or switching card. When fuses are used in a product, replace with same type and rating for continued protection against fire hazard. Chassis connections must only he used as shield connections for measuring circuits, NOT as safety earth ground connections. If you are using a te

32、st fixture, keep the lid closed while power is ap- plied to the device under test. Safe operation requires the use of a lid interlock. Ifa screw is present, connect it to safety earth ground using the wire recommended in the user documentation. The n ! symbol on an instrument indicates that the user

33、 should re- fer to the operating instructions located in the manual. Then symbol on an instrument shows that it can source or mea- sure 1000 volts or more, including the combined effect of normal and common mode voltages. Use standard safety precautions to avoid personal contact with these voltages.

34、 The WARNING heading in a manual explains dangers that might result in personal injury or death. Always read the associated infor- mation very carefully before performing the indicated procedure. The CAUTION heading in a manual explains hazards that could damage the instrument. Such damage may inval

35、idate the warranty. lnslrumentation and accessories shall not be connected to humans. Before performing any maintenance, disconnect the line cord and all test cables. To maintain protection from electric shock and fire, replacement components in mains circuits, including the power transformer, test

36、leads, and input jacks, must be purchased from Keithley Instru- merits. Standard fuses, with applicable national safety approvals, may be used if the rating and type are the same. Other components that are not safety related may be purchased from other suppliers as long as they are equivalent to the

37、 original component. (Note that se- lected parts should be purchased only through Keithley Instruments to maintain accumcy and functionality of the product.) If you are unsure about the applicability of a replacement component, call a Keithley Instruments office for information. To clean an instrume

38、nt, use a damp cloth or mild, water based cleaner. Clean the exterior of the instrument only. Do not apply cleaner directly to the instrument or allow liquids to enter or spill on the insrmment. Products that consist of a circuit board with no case or chassis (e.g., data acquisition board for instal

39、lation into a computer) should never require cleaning if handled according to in- structions. If the board becomes contaminated and operation is af- fected, the board should be returned to the factory for proper cleaning/servicing. 7JOl 197A 5%-D records data at one of seven selectable rates from 3

40、reading/second to 1 reading/hour or by manual trigger (r=6). Also detects and stores maximum and mini- mum readings continuously while in the data logger mode. 1. STO/CLR - Pressing this button initiates the log- ging sequence. Pressing this button a second time turns off the data logger. For r=6 ra

41、te (manual trig- ger) every time a reading is desired, press the STO/ CLR button. 2. RCL - Pressing and holding in this button scrolls the data pointer. To read the data at a certain point, simply release the button. The logged readings are storedinbufferlocationsO1 tolOZ.They aredepicted on the fro

42、nt panel as follows: Buffer location #I is represented by n=Ol. AC/DC -This button is used along with the volts (V), current (A), and dB functions. Depressing (in) this button selects AC, releasing (out) this button selects DC. AC Q is invalid condition. See Table 2-1. V - Depressing this button sel

43、ects the volts function. IL - Depressing this button selects the ohms function. The AC/DC button must be released (out). A-Depressing (in) this button selects the current func- tion. Up to 2A on red and black input jacks and up to 1OA 2-4 with the black and white input jacks. Refer to paragraph 2.4.

44、3. RANGE BUTTONS 1. 2. Depressing AUTO button aLlows volts and ohms to autorange. In current, it selects the 10A range. There is no autorange function for current. Manual ranging is accomplished by depressing the appropriate range button. 2.4.3 Input Terminals The input terminals are intended to be

45、used with safety shrouded test leads to help minimize the possibility of contact with live circuits. Safety shrouded test leads (Model 1751) are supplied with the Model 197A. Always disconnect all unused test leads from the instrument. HI and LO INPUT (Red and Black) -Use this pair of ter- minals fo

46、r all volt, ohm, milliamp and dB measurements. 1OA and LO (White and Black) -Use this pair of termi- nals for measuring current up to 10A (up to 2OA for 15 seconds). OHMS Sense HI and LO - Use this pair of terminals along with HI and LO input for four wire resistance measurements. 2.4.4 Current Fuse

47、 Replacement The current fuse protects the ZOO through 2OOOmA ranges from an input current greater than 2A. To replace the current fuse, perform the following steps: NOTE The front panel current fuse (F101) is rated at 2A. With aZO,OOO count display, the2Arange can momentarily (approx. one minute) r

48、ead 2.2A before the fuse will blow. This 10% over- range will not harm the instrument. 1. Turn off the power and disconnect the power line and test leads. 2. Place the end of a tit-blade screwdriver into the slot in the fuse holder on the front panel. Press in slightly SECTION 2 Bench Operation and

49、rotate the fuse carrier on quarter turn counterclock- wise. Release pressure and remove the fuse carrier and the fuse. 3. Remove the defective fuse and replace it with the fol- lowing type: ZA, 25OV, 3AG, normal-blow (Keithley part number FU-13) or equivalent. CAUTION Use only the recommended fuse type. If a fuse with a higher current rating is installed, instru- ment damage may occur. 2.4.5 Rear Panel Switches The rear panel of the Model 197A is shown in Figure 2-2. Note that if an IEEE-488 interface mo