KEI 2750 Service 电路图.pdf

《KEI 2750 Service 电路图.pdf》由会员分享，可在线阅读，更多相关《KEI 2750 Service 电路图.pdf（188页珍藏版）》请在收音机爱好者资料库上搜索。

1、Model 2750Multimeter/Switch System Service Manual A G R E A T E RM E A S U R E O F C O N F I D E N C E Cover.qxd 2/20/01 10:13 AM Page 2 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 3 years from

2、date of shipment. 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 defec- tiv

3、e. To exercise this 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

4、product returned, transportation 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 modifi cation without Keithleys express written consent, o

5、r misuse of any product or part. This warranty also does not apply to fuses, software, non-recharge- able batteries, damage from battery leakage, or problems arising from normal wear or failure to follow instruc- tions. THIS WARRANTY IS IN LIEU OF ALL OTHER WARRANTIES, EXPRESSED OR IMPLIED, INCLUDIN

6、G ANY IMPLIED WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR USE. THE REMEDIES PROVIDED 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 O

7、UT OF THE USE OF ITS INSTRUMENTS AND SOFTWARE EVEN IF KEITHLEY INSTRUMENTS, INC., HAS BEEN ADVISED IN ADVANCE OF THE POSSIBILITY OF SUCH DAMAGES. SUCH EXCLUDED DAM- AGES SHALL INCLUDE, BUT ARE NOT LIMITED TO: COSTS OF REMOVAL AND INSTALLATION, LOSSES SUSTAINED AS THE RESULT OF INJURY TO ANY PERSON,

8、OR DAMAGE TO PROPERTY. Keithley Instruments, Inc. 28775 Aurora Road Cleveland, OH 44139 440-248-0400 Fax: 440-248-6168 BELGIUM:Keithley Instruments B.V. Bergensesteenweg 709 B-1600 Sint-Pieters-Leeuw 02/363 00 40 Fax: 02/363 00 64 CHINA:Keithley Instruments China Yuan Chen Xin Building, Room 705 12

9、Yumin Road, Dewai, Madian Beijing 100029 8610-62022886 Fax: 8610-62022892 FRANCE:Keithley Instruments Sarl 3, alle des Garays 91127 Palaiseau Cedex 01-64 53 20 20 Fax: 01-60 11 77 26 GERMANY:Keithley Instruments GmbH Landsberger Strasse 65 82110 Germering 089/84 93 07-40 Fax: 089/84 93 07-34 GREAT B

10、RITAIN:Keithley Instruments Ltd The Minster 58 Portman Road Reading, Berkshire RG30 1EA 0118-9 57 56 66 Fax: 0118-9 59 64 69 INDIA:Keithley Instruments GmbHFlat 2B, WILOCRISSA 14, Rest House Crescent Bangalore 560 001 91-80-509-1320/21 Fax: 91-80-509-1322 ITALY:Keithley Instruments s.r.l. Viale S. G

11、imignano, 38 20146 Milano 02-48 39 16 01 Fax: 02-48 30 22 74 NETHERLANDS:Keithley Instruments B.V. Postbus 559 4200 AN Gorinchem 0183-635333 Fax: 0183-630821 SWITZERLAND:Keithley Instruments SA Kriesbachstrasse 4 8600 Dbendorf 01-821 94 44 Fax: 01-820 30 81 TAIWAN:Keithley Instruments Taiwan 1 Fl. 8

12、5 Po Ai Street Hsinchu, Taiwan, R.O.C. 886-3572-9077 Fax: 886-3572-903 9/00 RadioFans.CN 收音机爱 好者资料库 Model 2750 Multimeter/Switch System Service Manual 2001, Keithley Instruments, Inc. All rights reserved. Cleveland, Ohio, U.S.A. First Printing, March 2001 Document Number: 2750-902-01 Rev. A RadioFan

13、s.CN 收音机爱 好者资料库 Manual Print History The print history shown below lists the printing dates of all Revisions and Addenda created for this manual. The Revision Level letter increases alphabetically as the manual undergoes sub- sequent updates. Addenda, which are released between Revisions, contain im

14、portant change in- formation that the user should incorporate immediately into the manual. Addenda are numbered sequentially. When a new Revision is created, all Addenda associated with the previous Revision of the manual are incorporated into the new Revision of the manual. Each new Revision includ

15、es a revised copy of this print history page. Revision A (Document Number 2750-902-01).March 2001 All Keithley product names are trademarks or registered trademarks of Keithley Instruments, Inc. Other brand names are trademarks or registered trademarks of their respective holders. Safety Precautions

16、 The following safety precautions should be observed before using this product and any associated in- strumentation. Although some instruments and accessories would normally be used with non-hazardous voltages, there are situations where hazardous conditions may be present. This product is intended

17、for use by qualifi ed personnel who recognize shock hazards and are familiar with the safety precautions required to avoid possible injury. Read the operating information carefully before using the product. The types of product users are: Responsible body is the individual or group responsible for t

18、he use and maintenance of equipment, for ensuring that the equipment is operated within its specifi cations and operating limits, and for ensuring that operators are adequately trained. Operators use the product for its intended function. They must be trained in electrical safety procedures and prop

19、er use of the instrument. They must be protected from electric shock and contact with hazardous live circuits. Maintenance personnel perform routine procedures on the product to keep it operating, for example, setting the line voltage or replacing consumable materials. Maintenance procedures are des

20、cribed in the manual. The procedures explicitly state if the operator may perform them. Otherwise, they should be performed only by service personnel. Service personnel are trained to work on live circuits, and perform safe installations and repairs of prod- ucts. Only properly trained service perso

21、nnel may perform installation and service procedures. Keithley products are designed for use with electrical signals that are rated Installation Category I and Installation Category II, as described in the International Electrotechnical Commission (IEC) Standard IEC 60664. Most measurement, control,

22、 and data I/O signals are Installation Category I and must not be directly connected to mains voltage or to voltage sources with high transient over-voltages. Installa- tion Category II connections require protection for high transient over-voltages often associated with lo- cal AC mains connections

23、. The user should assume all measurement, control, and data I/O connections are for connection to Category I sources unless otherwise marked or described in the Manual. Exercise extreme caution when a shock hazard is present. Lethal voltage may be present on cable con- nector jacks or test fi xtures

24、. The American National Standards Institute (ANSI) states that a shock haz- ard exists when voltage 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 of this product must

25、 be protected from electric shock at all times. The responsible body must en- sure that users are prevented access and/or insulated from every connection point. In some cases, con- nections must be exposed to potential human contact. Product users in these circumstances must be trained to protect th

26、emselves from the risk of electric shock. If the circuit is capable of operating at or above 1000 volts, no conductive part of the circuit may be exposed. Do not connect switching cards directly to unlimited power circuits. They are intended to be used with impedance limited sources. NEVER connect s

27、witching cards directly to AC mains. When connecting sources to switching cards, install protective devices to limit fault current and voltage to the card. Before operating an instrument, make sure the line cord is connected to a properly grounded power re- ceptacle. Inspect the connecting cables, t

28、est leads, and jumpers for possible wear, cracks, or breaks be- fore each use. When installing equipment where access to the main power cord is restricted, such as rack mounting, a separate main input power disconnect device must be provided, in close proximity to the equipment and within easy reach

29、 of the operator. For maximum safety, do not touch the product, test cables, or any other instruments 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 jumpers, installing or re

30、moving switching cards, or making internal changes, such as installing or removing jumpers. Do not touch any object that could provide a current path to the common side of the circuit under test or power line (earth) ground. Always make measurements with dry hands while standing on a dry, insulated

31、surface ca- pable of withstanding the voltage being measured. The instrument and accessories must be used in accordance with its specifi cations and operating instructions or the safety of the equipment may be impaired. Do not exceed the maximum signal levels of the instruments and accessories, as d

32、efi ned in the specifi cations and operating information, and as shown on the instrument or test fi xture panels, or switching card. When fuses are used in a product, replace with same type and rating for continued protection against fi re hazard. Chassis connections must only be used as shield conn

33、ections for measuring circuits, NOT as safety earth ground connections. If you are using a test fi xture, keep the lid closed while power is applied to the device under test. Safe operation requires the use of a lid interlock. If a screw is present, connect it to safety earth ground using the wire r

34、ecommended in the user documentation. The symbol on an instrument indicates that the user should refer to the operating instructions located in the manual. The symbol on an instrument shows that it can source or measure 1000 volts or more, including the com- bined effect of normal and common mode vo

35、ltages. Use standard safety precautions to avoid personal contact with these voltages. The WARNING heading in a manual explains dangers that might result in personal injury or death. Always read the associated information very carefully before performing the indicated procedure. The CAUTION heading

36、in a manual explains hazards that could damage the instrument. Such damage may invalidate the warranty. Instrumentation 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 fi

37、 re, replacement components in mains circuits, including the power transformer, test leads, and input jacks, must be purchased from Keithley Instruments. Standard fuses, with applicable national safety approvals, may be used if the rating and type are the same. Other components that are not safety r

38、elated may be purchased from other suppliers as long as they are equivalent to the original component. (Note that selected parts should be purchased only through Keithley Instruments to maintain ac- curacy and functionality of the product.) If you are unsure about the applicability of a replacement

39、component, call a Keithley Instruments offi ce for information. To clean an instrument, 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 instrument. Prod- ucts that cons

40、ist of a circuit board with no case or chassis (e.g., data acquisition board for installation into a computer) should never require cleaning if handled according to instructions. If the board becomes contami- nated and operation is affected, the board should be returned to the factory for proper cle

41、aning/servicing. ! Rev. 2/01 Table of Contents 1 Performance Verifi cation Introduction . 1-2 Verifi cation test requirements . 1-3 Environmental conditions . 1-3 Warmup period . 1-3 Line power . 1-3 Recommended test equipment . 1-4 Verifi cation limits . 1-5 Example reading limit calculation . 1-5

42、Calculating resistance reading limits . 1-5 Restoring factory defaults . 1-6 Performing the verifi cation test procedures . 1-6 Verifi cation test summary . 1-6 Test considerations . 1-7 Model 2750 verifi cation . 1-8 Verifying DC voltage . 1-8 Verifying AC voltage . 1-10 Verifying DC current . 1-11

43、 Verifying AC current . 1-13 Verifying normal resistance . 1-14 Verifying dry circuit resistance . 1-16 Verifying temperature . 1-18 Verifying frequency . 1-20 Model 7700 verifi cation . 1-20 Verifying DC voltage . 1-21 Verifying AC voltage . 1-22 Verifying DC current . 1-24 Verifying AC current . 1-25 Verifying normal resistance . 1-26 Verifying dry circuit resistance . 1-28 Verifying temperature . 1-31 Verifying frequency . 1-34 Verifying ratio and average . 1-35 2Calibration Introduction .