Yamaha CT-7000 Service Manual
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Yamaha CT-7000 Service Manual

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  • Page 2 YAMAHA Hi-Fi STEREO SERVICE MANUAL FM STEREO TUNER MODEL CT-7000 Printed in Japan 10-74...

  • Page 3: Specifications

    7 000 CONTENTS SPECIFICATIONS EXTERNAL VIEWS FRONT PANEL ..... . REAR PANEL (U .S . & CANADIAN MODELS) REAR PANEL (EUROPEAN MODEL) INTERNAL VIEWS TOP VIEW ..BOTTOM VIEW ..CIRCUIT DESCRIPTION .. PARTIAL DISASSEMBLY . DIAL MECHANISM ..MEASUREMENT AND ADJUSTMENT PRINTED CIRCUIT BOARD ..

  • Page 4: External View

    CT-7000 EXTERNAL VIEW FRONT PANEL ®® REAR PANEL (U.S.& CANADIAN MODELS) REAR PANEL (EUROPEAN MODEL) 2 ---- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --...

  • Page 6: Internal View

    CT-7000 INTERNAL VIEW TOP VIEW TUNING METER SIGNAL METER DIAL POINTER DIAL LAMP CIRCUIT BOARD MULTIPLEX DEMODULATOR CIRCUIT BOARD POWER TRANSFORMER IF AMPLIFIER CIRCUIT BOARD RF PACK DISCRIMINATOR CIRCUIT BOARD METER LAMP CIRCUIT BOARD PULLEY FOR VARIABLE CAPACITOR BOTTOM VIEW...

  • Page 7: Circuit Description

    CT-7000 CIRCUIT DESCRIPTION METER CIRCUIT This circuit has two functions. e permits almost Signal-minus-Multipath deflection. This system permits direct feeding of signals with strengths from OdB,u owner to find the best balance of strong and to 1 OOciB,u to the Signal meter. The other permits "clean"...
  • Page 8 - and thi s ide extra protection aga in s t tu ne the nearby station. T o avoid this problem the su pe ri or feature of the Yamaha system.
  • Page 9 CT-7000 STATION INDICATION SIGNAL 12V60mA AFC/STATION LAMP Fig. 3 Operation 3. At the same time, this potential is fed to the base 1. Touching the tuning knob with your finger passes of Tr4, so that that transistor comes on and grounds the electric potential in the human body to the TS Tr5 with 15k.Q.

  • Page 10: Muting Circuit

    CT-7000 MUTING CIRCUIT circuit also functions to cut transient noises, a function This circuit eliminates weak signals and inter-station which will be explained in another section. noise during tuning, or in case of station drift. This Operation age is contained in e2; when it is higher, positive voltage is present.
  • Page 11 CT-7000 PHASE LOCKED LOOP CIRCUIT This circuit accurately creates a switching signal which to match the oscillator 19kHz pilot signal to the broad­ cast pilot signal. divides the stereo components of the signal. It is divided into two parts: an oscillator and a section...
  • Page 12 CT-7000 19kHz 2. Phase Comparison and Detection Section obtained. Since the square wave signals driv­ 19kHz a. The pilot signal, a composite signal neces­ ing Tr2 and Tr3 are in opposite phase, Vc' and sary for phase comparison and detection, is selected Vd' are activated alternately.
  • Page 13 CT-7000 3. Oscillation Section and Phase Comparison Detection 2-3. Potential at points@ and@ becomes that shown Section at a· b' c' and d' in the chart 10 and 11 . Phase differ­ The output potential of the phase comparison detec­...
  • Page 14 CT-7000 STEREO/MONO DRIVE AND STEREO INDICATOR CIRCUIT This circuit receives stereo signals strong enough locked the demodulator operates and the stereo indi­ for stereo reception. When the circuit is phase cator lamp lights, which is this circuit's function. Operation 1. The...
  • Page 15 CT-7000 MULTIPLEX DEMODULATOR CIRCUIT This circuit double tunes the composite signal by a switching method, thus separating out the left and right channel audio signals. SIGNAL COMPOSITE SIGNAL (INPUT) Fig. 8 Operation The composite signal entering at is amplified by Trl off, switching Tr7 off).
  • Page 17 CT-7000 5. Multiplex Demodulator Circuit Board Removal 5-1. Remove the cabinet. 5-2. Remove screws (1�4) shown in Photo 5, then cover. take off the shield 5-3. Remove screws (1�4) Photo 6, t hen board. take out the circuit 6. Discriminator Circuit Board Removal 6-1.
  • Page 18 CT-7000 Front Panel Removal 12-1. Follow steps 2-1 and 2-2. 12-2. Remove connectors (2�5), (8) and (11 shown in Photo 4, then remove the switch circuit board. 12-3. Loosen the two tuning knob fixing screws shown Photo 4 in the direction of the arrow, using a wrench.
  • Page 19 CT-7000 Photo 14 Photo 15 DIAL MECHANISM...

  • Page 20: Measurement And Adjustment

    CT-7000 MEASUREMENT AND ADJUSTMENT 1. TUNER SECTION Before Adjustment ..After 30 minutes aging with power switch on and each circuit board cover removed. TERMINAL TO BE RATING OR ADJUSTMENT & REMARKS STEP CONNECTED ADJUSTMENT HOW TO ADJUST...

  • Page 21: How To Adjust

    CT-70 00 TERMINAL TO BE ADJUSTMENT RATING OR & REMARKS STEP CONNECTED ADJUSTMENT HOW TO ADJUST ITEM STANDARD INSTRUMENT REOUI RED Muting Level Antenna terminal (300.n) Muting VR=30dBI' IF circuit board Turn slowly from L to Once set, dif· FM signal generator Muting Adj.

  • Page 22: Adjustment Point

    CT-7000 ADJUSTMENT POINT 2. PRECAUTIONS AND STEPS IN CORRECTING FAULTS able 1. Replacing Parts resistors. adjustable trimmers and inductors) must 2 below. 1-1. be readjusted as explained in part en it is necessary to replace any parts in the 1-3.
  • Page 23 CT-7000 3. SPECIFICATION ASSURANCE CONDITIONS ITEM MEASUREMENT CONDITION VALUE Test Temperature 25 ± 10°C Test Humidity 20°C ± u.s. AC Input Voltage/Frequency 117V 45-65Hz 105-135V Europe 110V 90-115V 45-65Hz 130V 45-65Hz 110-135V 220V 200-240V 45-65Hz 240V 220-260V 45-65Hz Vibration Noise Low enough to be no test influence.
  • Page 26 CT-7000 CONTROL CIRCUIT BOARD NA06484...
  • Page 27 CT-7000 SWITCH CIRCUIT BOARD NA06487 POWER CIRCUIT BOARD NA06485...

  • Page 28: Block Diagram

    CT-7000 VOLUME CIRCUIT BOARD NA06488 METER LAMP CIRCUIT BOARD NA06490 MUTING OUTPUT HEADPHONE LEVEL LEVEL LAMP CIRCUIT BOARD NA06489 BLOCK DIAGRAM...

  • Page 31: Parts List

    CT-7000 PARTS LIST FRONT VIEW INTERNAL VIEW...

  • Page 32: Exploded View

    CT-7000 INTERNAL VIEW EXPLODED VIEW...
  • Page 33 CT-7000 CT-7000 INTERNAL VIEW INTERNAL VIEW (BOTTOM) (BOTTOM) INTERNAL VIEW INTERNAL VIEW...
  • Page 35 CT-7000 R ef . Common P a rt N o . e s c r i p t io Remarks N o . Models C i r cu i t :j:\:62754 NA06480 board :..- FP14647 4.71' - F 11 JI.-::J /7'/-tt Tantalum capacitor ;..-...
  • Page 36 CT-7000 Common Ref. D e s c r i p t Remarks Part No. Models /:,/7.11- iA07630 Transis-tor 2 SA763 WL 4 or 5 " " iC04608 2 SC460 B or C iG00039 !'PC 577H iF00004 Diode 151555 HY00016 Metal glaze variable resistor 11 JL-- ·;fl.,.
  • Page 37 CT-70 00 Ref. Part No. Descri Common Remarks Models ;;1.5'11.-�fv-.A'VR glaze variable resistor CR19R B-1KO HY00019 Metal HY00016 B-22KO " " :::J GE20008 MPX coil =GE6057 X !ilil ;iE GE20011 fixed coil 47mH :::J =GE6062 " 7 /�:A :I!- iA07630 Transistor 2SA763 WL4 or...
  • Page 38 CT-7000 Ref. Common Part No. D e s c r i p t i Remarks Models " ::::J ::::J L840013 Connector 2403·4A titift7 z " " L860053 2403·6A " " L860054 2403-8A " L830022 Connector 2145·38 ::::J ::::J " "...
  • Page 39 CT-7000 Ref. Common Part No. D e s c r i p t i o n Remarks MOdels HR10007 Variable resistor RV16YP15S B-10K0 � HR10008 RV16YPG15S A-10Kx2 " " ::.- 7' � - " ® NA06489 Lamp circuit board #63870 ��...
  • Page 42 - Y A M A H A m � 1 887 NIPPON GAKKI CO., TO. HAMAMATSU, .JAPAN Printed in Japan 10-74...

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