Scott-LR-88-Service-Manual 电路图 维修手册.pdf

《Scott-LR-88-Service-Manual 电路图 维修手册.pdf》由会员分享，可在线阅读，更多相关《Scott-LR-88-Service-Manual 电路图 维修手册.pdf（198页珍藏版）》请在收音机爱好者资料库上搜索。

1、fUll COlOR CONSTRUCTION B001 LRBB . SDLID STATE A Mf M SlERIO RIOIIVIR - KIT RadioFans.CN 收音机爱 好者资料库 HERMON SCOTT, Audio Pioneer Hermon H. Scott, SB and SM in electrical engineering, MIT; F ellow, Intitute of Electrical and Electronics Engineers; Fe/lou;, Acoustical Society of America; Fellow, past

2、president, Audio Engineering Society; past chairman of board, Institute of High Employment of the Physically Handicapped; Inventor, electronic sweep circuit, RC oscillator, dynamic noise suppressor etc., with over 100 U.S. and foreign patents; MIT alumni council; Trustee, Opera Company of Boston; Tr

3、ustee, Boston Ballet; Trustee, Deaconess Hospital; Trustee, Union Savings Bank; Registered Professional Engineer, Mass.; Author, numerous Fidelity; Potts M edal of Audio Engineering Society for outsta11di11g contribution to audio science; Distinguished Service Au.:ard of Presidents Committee on pion

4、eering articles in electronics, acoustics, and sound reproduction. Hermon H. Scotts own interest in music, grand opera in particular, bas prompted him to provide music lovers with the finest sound reproducing equip ment since 1946, wben be built the first true high fidelity amplifier. Originally Sco

5、tt manufactured chiefly precision sound measuring and broadcast equipment. He built a few wide-range amplifiers for bis own use. Friends and engineers were so im pressed with their sound qualities that he manu factured them for wider distribution. As a result, both a new business and a new industry

6、were launched. Many of the original Scott amplifiers are still in service and occasionally are brought to the Scott plant for checkups. With pride, engineers report that they still operate perfectly. Herman Scott always insisted that his companys laboratories be accessible ta owners of Scott equipme

7、nt, no matter when or wbere purcbased, for adjustrnent or service so that equipment can be kept functioning in accordance with original specifications. Many significant developments have corne from Scotts engineering laboratories, among them the Model 99 amplifier in 1953 which did not need to be bi

8、dden from view thereby setting a precedent in appearance which the industry bas since followed. A FEV OF THE I1IPORTANT FIRSTS by H. H. Scott First to use wide-band circuitry successfully in high fidelity FM tuners. First to market an F:11 multiplex stereo tuner and adaptor employing the FCC approve

9、d transmission system. First stereo electronic balancing system. First dynaural noise suppressor. First wide-rangc console system which produced component quality sound without acoustic feedback. First professional quality transistor kits will full color instruction books. First consumer high fideli

10、ty Integrated Circuit audio amplifier. First Integrated Circuit F1 tuner. First molded multi-tray, cybernetically engineered KIT-PAKD. First Field Effect transistor tuner. The H. H. Scott plant in Maynard, Massachusetts -,.-; - - c;.-;-1-:C: RadioFans.CN 收音机爱 好者资料库 Solid State AM/FM Stereo Receiver

11、Scottkit Your new Scottkit represents the culmination of years of research and planning. When you have completed your Scottkit, you can be sure it is the equal of superb H. H. Scott factory-wired components. The quality of your finished kit is assured because the same conservatively rated, factory-t

12、ested parts are specified for Scottkits as for Scott factory-wired components. Tirne tested Scott circuitry has been especially redesigned for kit-building and home testing to assure perfect performance. The Scott instruction book, with large-scale, full-color illustrations is de signed to make kit-

13、building foolproof. With these illustrations and with the step-by-step testing procedure you can automatically locate and correct any errors you may make. Before a new Scottkit is marketed, it is thoroughly pretested: 1.Instruction book drafts are hand-colored for an evaluation run by many carefully

14、 selected consumers. This panel consists of doctors, businessmen, office and factory workers, housewives, engineers, students . many of whom have never built a kit before. Each builder notes any suggested changes in the instruction book draft, and returns the draft with the completed kit to the Scot

15、t Engineering Department. 2.Each of the completed kits is carefully tested and evaluated. Typical figures from the panel-built units are used for determining the specifications which follow. (Advances in technology may change these specifications in the future.) 3.All instruction book drafts are tho

16、rougly examined for the annotated suggestions made by the consumer panel, and worthwhile changes are included in the finished book. This careful evaluation and testing means your Scottkit will be easy to build and give many years of trouble-free service. Relax . . . have a good time . . . you are ab

17、out to build a superb piece of high fidelity equipment. RadioFans.CN 收音机爱 好者资料库 Table of Contents TECHNICAL SPECIFICATIONS . 3 HI FI DICTIONARY . 5 RESISTOR COLOR CODE . 8 SECTION 1 GETTING STARTED . 9 1.1 Using the KIT-PAK and Unpacking . 9 1.2 Construction Proceclures For This Kit . 9 1.3 The Doub

18、le Check System . 10 1.4 Tools For Building The Kit . 11 1.5 Solclering And Wiring Instructions . 12 1.6 What To Do If You :llake A 11istake . 16 1.7 Types of Wire . 17 1.8 Photographs Of vVirecl Kit . 18, 19 SECTION 2 PARTS LIST . 20 SECTION 3 KIT CONSTRUCTION . 28 3.1 Rear Chassis . 28 3.2 110/2:2

19、0 Volt Conversion Units (part of Croup 4) . 34 3.3 Input Switch . 36 3.4 Tuner Chassis . 38 3.5 Tone Control Driver Board . 45 3.6 Front Chassis . 47 3.7 Main Chassis (Croups 14 -24) . 49 3.8 Lamp Sockcts-Panel-Dial Cord-A:II Antenna (Croups 25 - 28) 61 SECTION 4 TESTINC, ADJUSTllC it is expressed i

20、n decimal parts of a farad. ( See Fre quently Used Prefixes.) class A amplifier: a vacuum tube or transistor amplifier stage in which the bias value is chosen for plate or col Iector current flow throughout a full cycle of the signal. The average current flow with no signal applied is equal to the c

21、urrent flow with signal. This type of amplifier is normally used in preamplifler stages. As a power stage, its efficiency is low. 5 class B amplifier: an amplifier stage consisting of two tubes or two transistors in which the bias value is chosen for approximately zero plate or collector current whe

22、n no signal is applied. Current flows during approximately half of the cycle in each device. The average current greatly increases with signal. This type of amplifier is normally used in power output stages; its efficiency is high. coaxial cable: a cable with one ( or more) insulated con ductors com

23、pletely surrounded by a cylindrical shield (see Cable). The shield reduces pickup of hum and noise. converter: the section of a tuner that converts the in coming RF signal to a signal of fixed lower frequency, known as the intermediate frequency (abbreviated IF). Includes the oscillator and the conv

24、erter device itself. continuous power output, rms: the maximum power output capability of an amplifier over an extended period of time without exceeding rated distortion rather than on a short burst, as in music power. The standard test frequency is 1000 Hz ( cycles per second). carrier frequency: t

25、he frequency of the original unmod ulated radio wave produced by a radio station. capture ratio: a measure of the ability of an FM tuner to suppress the weaker of two signais of identical fre quency, permitting the stronger signal alone to be heard. cross-modulation: interference of one station by a

26、nother stronger station, resulting from the interaction of their signais within the tuner. The ability of the tuners front end to handle weak and strong signais. Expressed in dB, a higher number is usually more desirable. crossover distortion: in a Class B push-pull amplifier, one output transistor

27、( or tube) produces the positive part of the signal, and the other transistor the negative half. Crossover distortion occurs when the transfer from one transistor to the other does not take place smoothly. This form of distortion is particularly imp01tant because of its effect at low listening level

28、s. current: the movement of electrons through a conductor ( see ampere) . cycle: ( see ac). damping: the ability of the amplifier to maintain control over the speaker. High damping assists a speaker in cleanly reproducing transients. dB (decibel-no longer designated db): a unit of mea surement for t

29、he power gain or Joss in signal strength, ex pressed in Iogarithmic form. Specifically, I power output dB gain or loss = orr 10 =- - - 0 power input In terms of voltage or current, for a given impedance, dB 20 I voltage or current output gain or Joss = og10 1 . . vo tage or current mput de (direct c

30、urrent-no longer designated DC): a current that flows continuously in one direction. de-emphasis: (see equalization). detector: the section of a tuner that converts the modu lated carrier to an audio output. diode: device that conducts electricity in one direction only. distortion: any unwanted chan

31、ge in the waveform of a signal. efficiency: the ratio of the output power of a device to its input power, usually expressed in per cent. equalization: modification of the frequency response of a device in a desired manner to achieve a specific result, such as reduction of background noise. feedback:

32、 involves feeding a small part of the output of an amplifier back to the input. If the signal is fed back so as to cause a reduction in gain, it is called nega tive feedback. It provides a reduction in distortion. field-effect transistor: a type of solid-state device which contrais current flow by m

33、eans of an electrostatic field. It has lower noise and generates Jess distortion than a normal bi-polar transistor. filter: a circuit designed to pass certain ranges of fre quency while restricting the passage of others. flutter: rapid fluctuations in speed caused by mechanical deficicncies in turnt

34、ables or tape recorders, resulting in variations in pitch. FM (frequency modulation): the method of transmission in which a signal of constant amplitude ( the carrier) is varied in frequency in accordance with the signal (voice or music). frequencies: ( see ac). front end: the term used to describe

35、the section of the tuner that selects the desired station, amplifies it and con verts it to the IF frequency. Includes an RF amplifier and a converter. fuse: a protective device that disconnects the circuit when the current exceeds a certain level. gain: increase in signal strength. Usually expresse

36、d in decibels (dB) . ground: a connection, intentional or accidentai, between an electric circuit and the earth or a chassis serving in place of the earth. harmonie distortion: the unwanted generation of addi tional signal components that are multiples of the fonda mental frequency of the signal. Hz

37、 (hertz): new international designation for cycles per second ( cps). (See ac). hum: a low-pitched, undesired sound usually caused by improper filtering of the ac power supply, or poor shield ing of the same circuit. Hum is composed of the power line frequency and its harmonies. IF (intermediate fre

38、quency): It is easier to build a tuned (selective) amplifier for a fixed frequency than one that is adjustable over a range of frequencies. An intermediate frequency ( fixed) is produced by the converter. ( See con verter). 6 IHF: Institute of High Fidelity. IM intermodulation distortion): the gener

39、ation of un wanted signais by the interaction of two or more signais of different frequencies. IM products are usually not multiples of the frequencies of the input signais; that is, not harmonically related to them. impedance: the property of a circuit that determines the amount of flow of alternat

40、ing current where a given voltage is applied. It is measured in ohms. insulator: a part that does not conduct electricity. insulation: non-conductive material used to prevent the flow of electricity to undesired areas. integrated circuit monolithic): a miniaturized electronic circuit composed of res

41、istors, capacitors and semiconduc tors ( diodes and transistors) produced by photo-chemical and other transistor manufactu1ing techniques. A com plete circuit frequently measures fro .02 to .2 and is mounted in a transistor-sized case with leads. jack: an electrical receptacle into which a plug is i

42、nserted to complete an electiic circuit. lead: a wire that connects two or more points in a circuit pronounced leed). limiter: an amplifier stage in an FM tuner that removes variations in the amplitude of the signal including those caused by atmospheric disturbances and man-made inter ference, which

43、 would otherwise cause noisy reception. mixer: (see converter). modulation: see AM and FM. The process of super imposing music or voice on a carrier frequency. monophonie (sometimes known as monaural transmis sion): a transmission system combining ail input signais in a single channel in such a mann

44、er that all reproduced sounds emanate or seem to emanate from the same loca tion. multiplex mpx): a technique whereby two independent stereo signais are transmitted by a single FM station and then separated at the receiver for stereophonic reproduc tion. music power or dynamic power (IHF standard):

45、maxi mum power output of an amplifier that can be obtained without exceeding ratcd distortion measured over a time interval sho1t enough so that power supply voltages have not changed from their no-signal values. These conditions are representative of the situation that occurs when music is being reproduced. Standard test frequency is 1000 Hz ( cycles per second) . network: a combination of electrical components de signed for a specific fonction