Jvc-PCV-77-Service-Manual电路原理图.pdf

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1、t:l f- “1 f- et f- N CD P-t) (f) H Z h:J o , PC V 77 A BEG U V JVC pc-V77 AlB/E/G/UN Free service manuals Gratis schema s Digitized by IAWW. frceservicemanuals.info An instruction booklet (B /E/G version) is provided with this manual. Contents Page Safety Precautions . . . . 2 Location of Main Parts

2、 3 Removal of Main Parts . . . . 4 Adjustment . . . . . . . 7 Block Diagram . . 12 Wiring Connections . 14 Standard Schematic Diagram . . 15 Location of P.C. Board Parts and Parts List Tuner P.C. Board Parts . . 20 DIN Board . . 23 Page Main P.C. Boad parts . 24 DTS P.C. Board parts . . . 2B Explode

3、d View of Speaker Box and Parts List . 29 jQ Exploded View of Mechanism Assembly . 30 Mechanism Component Parts List . 31 ill Exploded View of Enclosure Assembly . 32 Enclosure Assembly Parts List . . 33 Im Packing and Packing Parts List . . 35 rrn Accessories . Back Cover No. 1740-1 October 1987 tJ

4、 PC-V77 A /B/E/G/UN f-. et f- . N (j) P-o t ;J M M Ul M :0 H () i t- Ul H Z hj o Safety Precautions 1. The design of this product contains special hardware. Many circuits and components specially for safety purposes. For continued protection, no changes should be made to the original design unless a

5、uthorized in writing by the manufacturer. Replacement parts must be identical to those used in the original circuits. Service should be per formed by qualified personnel only. 2. Alterations of the design or circuitry of the product should not be made. Any design alterations or additions will void t

6、he manufacturers warranty and will further relieve the manufacturer of responsibility for personal injury or pro perty damage resulting therefrom. 3. Many electrical and mechanical parts in the product have special safety-related characteristics. These characteri stics are often not evident from vis

7、ual inspection nor can the protection afforded by them necessarily be obtained by using replacement components rated for higher voltage, wattage, etc. Replacement parts which have these special safety characteristics are identified in the parts list of Service manual. Electrical components hav ing s

8、uch features are identified by (Lt) on the schematics and parts list in Service manual. The use of a substitute replacement which does not have the same safety characteristics as the recommended replacement part shown in the parts list in Service manual may create shock, fire, or other hazards. 4 .

9、The leads in the products are routed and dressed with ties, clamps, tubings, barriers and/or the like to be separated from live parts, high temperature part, mov ing parts and/or sharp edges for the prevention of elec tric shock and fire hazard. When service is required, the original lead routing an

10、d dress should be observed, and they should be confirm ed to be returned to normal, after re -assembling. 5. Leakage current check (Safety for electrical shock hazard) A fter re-assembling the product, always perform an isola tion check on the exposed metal parts of the Products (antenna terminals,

11、knobs, metal cabinet, screw heads, earphone jack, control shafts, etc.) to be sure the pro duct is safe to operate without danger of electrical shock. 2 (No. 1740) Do not use a line isolation transformer during this check. Plug the AC line cord directly into the AC outlet. Us ing a “ Leakage Current

12、 Tester“, measure the leakage current from each exposed metal part of the cabinet, particularly any exposed metal part having a return path to the chassis, to a known good earth ground (water pipe, etc.). Any leakage current must not ex ceed 0.5 mA AC (r.m.s.). Alternate check method. Plug the AC li

13、ne cord directly into the AC outlet. Use an AC voltmeter having 1,000 ohms per volt or more sensitivity in the following manner. Connect a 1500 l 10 W resistor paralleled by a 0.15 /LF AC-type capacitor between an exposed metal part and a known good earth ground (water pipe, etc.) Measure the AC vol

14、tage across the resistor with the AC voltmeter. Move the resistor connection to each exposed metal part, particularly any exposed metal part having a return path to the chassis, and measure the AC voltage across the resistor. Now, reverse the plug in the AC outlet and repeat each measurement. Any vo

15、ltage measured must not exceed 0.75 V AC (r.m.s.). This corresponds to 0.5 mA AC (r .m .s.). AC VOLTMETER (HAVING 1000 ON, OR MORE SENSITIVITY I 0.1 5 /LF AC-TYPE GOOD EARTH GROUND PLACE THIS PROBE ON EACH EXPOSED METAL PART t:J C -cO C-et C-N (D P-t) j hj :0 M M (j) M :0 H n M S; t- (j) H Z hj 0 Lo

16、cation of Main Parts Main Board - Ass V Speaker Terminal Switch SEA Cover Power Transformer Fig . 2-1 AMP/SEA Board AssV CD Jack Assv INo. 1740) 3 PC-V77 A /B/E/G/UN Removal of Main Parts Cabinet Section Replacing the fuse Remove the rear cabinet the replace fuse Replacing the telescopic antenna. Re

17、move the screw at rear of the cabinet to replace the T . antenna. Rear cover 1) Remove the battery cover. 2) Remove eight screws G), and retaining the rear cabinet. 3) Disconnect the connector (CND 1) on Din Jack Board. (GN version) Amp. Board/SEA Board/3D speaker assy 1) Remove the two screws secur

18、ing the CD in-jack assy. 2) Remove the volume knob. 3) Remove the Function/Tape switch knob. 4) Pull and remove the SEA volume cover. 5) Remove the five screws and securing the board assy and 3D speaker assy. 6) Pull the entire assy slightly, then remove the head wire, motor tuner, etc. Tuner board

19、assy 1) Remove the wire connector for the tuner board. 2) Pull out the board ass y. Mechanism assy 1) Remove the six screws (j) . 2) Open the cassette door to remove . For reassembly, lift the cabinet rear slightly for easier assembly of the button and button lever. LeD indicator assy 1) Remove the

20、two screws 2) Remove the two screws 4 (No. 1740) securing the lamp assy. securing the LCD board. 7 Fig. 3-1 Fig. 3-2 Fig. 3-3 7 7 Fig. 3-4 hj :0 M M (j) M :0 H n M t- (j) H Z hj o Cassette door 1) Pull the lid up to remove. 2) Remove the door spring. 3) Close the door and remove the center shaft. Th

21、en remove the outer shaft and pull out toward the front panel. SEA board assy 1) Remove the two screws securing the pre-amp board. 2) Remove the four screws securing the SEA board. (For reassembly, insert the rec spring into the switchs slider hole.) The parts on the power amp board can still be rep

22、laced. Mechanism Section (Top View) (Bottom View) t-L -V / A /t;j / t:. / u /u/v Free se e manuals 3 Gralis schema s . -5 Digil izcd hy “ . frccscrviccmanuals.info Fig. 3-6 Motor bracket (Recording/playback deck) 1) Remove the three screws G). 2) Remove the chassis and M. bracket from the button sid

23、e. Then remove the bracket arm (panel). (The synchro arm can be removed from the pause lock. Return the pause lock after it is removed from the pro per position.) Head section 1) Remove the record/playback heads mounting screw and loosen screw . 2) Remove the erase head mounting screw and . Pinch ro

24、ller 1) Remove the pinch roller arm stopper E. Flywheel assy 1) Remove the C washer securing the capstan shaft. 2) Pull out the flywheel assy. Fig. 3-7 R(. PlilY Rw F F Stop Pausf Ejct Fig. 3-8 (No. 1740) 5 PC -V77 A /B/E/G/UN t:J hJ :0 M M (j) M :0 H n M t- (j) H Z hJ o Removal of the button assy f

25、rom the mechanical chassis. Leaf switch Press the switchs lock panel and raise from the left to remove. Gear IBelow the flywheel) Remove the C washer securing the gear. For reassembly, insert the Sensing Lever arm stand into the section. Lock arm Press the arm stopper from window , and pull to remov

26、e. Chassis removal 1) Remove the three 0, , and Cl) springs. 2) Remove the two screws 0. 3) Remove the two screws securing the capstan metal. 4) Gently remove the button ass y from the chassis. 6 INo. 1740) Fig. 3-9 Flywheel Fig. 3-10 Fig . 3-11 Fig. 3-12 “1 ?:J trI trI Ul trI ?:J H () I Ul H Z “1 o

27、 Main Adjustment Amplifier adjustments Conditions Power supply voltages : DC 1 2 V, Timer 1.5 V SEA controls Tape select Tapes used Input levels Output levels Item Head azimuth adjustment Tape speed adjustment Checking wow adjust to (10kHz) minimize phase difference between left and right channels.

28、To adjust deck A, adjust FWD first, then REV . After adjustment, apply screw locking compound. Fine adjustment after assembly should be done with the head cover removed . VTT712 After normal speed adjustment, perform double (3 kHz) speed adjustment 1. Adjust the normal speed of deck A to 3000 with V

29、R851 . 2. Check if Deck cru is at 3000 Hz + 10Hz. 3. To confirm high speed mode, play back Deck cru, then set Deck lA to record mode. VTT712 Deck B : 0 .35% (3 kHz) Deck A : 0.40% (JIS RMS) or less VTT724 Adjust VR10l , VR102 (deck A) and VR201 , (1 kHz) VR202 (deck B) so that the output of TP151 ,

30、TP251 and TP751 are - 21 dBm VTT739 With respect to their outputs at 1 kHz, the out-puts at TP151 and TP251 should be - 5 3 dB at 63 Hz, and - 1 3 d8 at 10kHz. (TS -8) Set beat cut switch S 7 21 to position 1 and ad -Normal tape just the oscillating frequency of C724 to 68 1 kHz with L 721. (Connect

31、 a 100 ) resistor in series when measuring.) (TS -8) Deck A: Adjust VR 122 (L ch) and VR222 (R ch) Normal tape so that the rec/play output of an input signal - 20 dB with respect to the reference level at 1 kHz is - 0 dB 1 dB at 10kHz. Deck B : Same as deck A . Measure outputs from TP151 and TP251.

32、(TS -8) Adjust VR 121 (L ch) and VR221 (R ch) so that Normal tape the level when recording and playing back an AUX (CD) IN signal - 20 dB with respect to the reference level is - 0 dBm 1 dB. Center Normal PC -V77 A/B/E/G/UN Recording normal tape TS-8 (UR) chrome tape TS -6 metal tape TS-7 Switch set

33、ting Adjustment location Tape/normal Deck A : Adjust FWD speed then REV Deck B Tape/Normal VR851 speed High speed Tape/Normal speed Tape/Normal Deck A speed L ch : VR10l R ch : VR201 Deck B L ch: VR102 R ch: VR202 Tape/Normal speed S721 L721 (Beat cut) 2 : 66 kHz 3 : 68 kHz L ch : VR 122 R ch : VR22

34、2 L ch : VR 121 R ch: VR221 (No. 1740) 7 PC -V77 A/B/E/G/UN o -cO 1- rt 1- N (j) 0. tJ Location of Adjustment H Z hJ o TP151 VR1 21 RECORDING GAIN Ad j. VR221 I JE=R ,i“ IVR 102 DEACK lA PLACLEVEL -iD PLAY BACK LEVEL Ad j Id) Lf-D VR10l r-JLVR=202 _ IDECKIA SPEED Adj Tuner Alignment BASIC CONDITIONS

35、 REC/ PLAY POWER SOURCE OF THE RECEIVER LOAD RESISTANCE OF THE RECEIVER MODULA TION OF SSG Item 1. AM IF ALIGNMENT 1 -1 Conditions of the receiver. (1 ) Power source: (2) Function switch position: (3) Band select switch: (4) Volume control: (5) SEA control: (6) Variable capacitor: VR851 FREOUENCY RE

36、SPONSE Adj VR 2225c;oB 0 BIAS FREOUENCY Adj VR I22 L721 Fig. 4-1 DC 12V, AC 120V 50 mW (0 .55 V)/6 11 400 Hz . 30% Description DC 7 V (When the power is supplied directly to the tuner in the receiver, the voltage should be adjusted to the proper level which shall be required by the tuner.) RADIO AM

37、Minimum gain position Center position Near the minimum capacity position where no signal come in. 1-2 Connection of Sweeper and the receiver ( 1) Tuner input: Positive side to TP3 (2) Tuner output: Positive side to TP6 1 Negative side t o TP7 1-3 Aligning position: CFT, T2 1-4 Alignment (Waveform):

38、Adjust AM I.F.T. (above mentioned aligning position) so that D maximum and symmetrical wave form can be obtained. In this case, the wavehead should be appeared at the center marker (450 kHz) on the scope of Sweeper. B (No_ 1740) ;J M M Ul M :u H n i t“ Ul H Z “1 o PC-V77 A /B/E/G/UIV Item Descriptio

39、n 2. FM IF ALIGNMENT 2-1 Conditions of the receiver (1 ) Power source: Same as mentioned in item 1-1 (2) Function switch position: RA DIO (3) Band select switch: FM (4) Volume control: Minimum gain position (5) SEA control: Center position (6) Variable capacitor: Near the minimum capacity position w

40、here no signal come in. 2-2 Connection of Sweeper and the receiver ( 1 ) Tuner input: Positive side to TP5 (2) Tuner output: Positive side to TP6 Negative side to TP7 NOTE a) Attach a capacitor (30 pF) and resistor (30 kO) to the positive side cable which shall be led from Sweeper input. b) Attach a

41、 resistor (100 km in series to the positive side cable which shall be led from Sweeper output. 2-3 Aligning position: Discriminate Waveform: T1 (“S“ curve waveform) 2-4 Alignment (Waveform): Adjust the discriminate coil (T1) so that “ S“ curve waveform may be changed to IF waveform as shown in follo

42、wing figure. NOTE The discriminators CF is yellow. Adjust the discriminate T2 so that above symmetrical IF Do not use one that is of another color. waveform may be changed to balanced “ S“ curve waveform. 3. AM RF ALIGNMENT 3- 1 Conditions of the receiver. (1 ) Power source: Same as mentioned in ite

43、m 1-1. (2) Function switch position: RA DIO (3) Volume control: 50mW (4) SEA control: Center position (5) Variable capacitor: Refer the following list shown in item 3-4 . 3-2 Conditions of SSG . (1) Modulation: Refer the basic condition (2) Frequency: Refer the following list shown in item 3-4 . (3)

44、 Output level of the attenuator in SSG : Approx. 50 mW 3-3 Power output measuring position: Speaker terminals 3-4 Alignment: Band Select Sort of Antenna to be Frequency of SSG Preset Memory No. Aligning Switch Position attached to SSG Position 1 520 kHz M5 L5 2 AM Turn L5 until the voltage of TP9 be

45、comes 4 .4 0.05 v. 3 or MW 4 600 kHz to be received 600 kHz (M2) L3 5 ( Adjustments after A M (MW) oscilla- ) 1,400 kHz to be received 1,400 kHz (M4) TC3 6 tion circuit replacement initial sett-Adjust the above aligning position (L3 & TC3) repeatedly so that ing . (See page 10) the tuner can be obta

46、ined the best sensitivity. 7 281 MHz M5 L6 8 Loop Antenna Turn L6 until the voltage of TP9 becomes 4.4 0 .02 V . 9 10 LW 164 kHz to be received 164 kHz (M 1) L4 11 272 kHz to be received 272 kHz (M 5) TC-4 12 (B /E/GIV Adjust the above aligning position (L4 & TC -4) repeatedly so Version) that the t

47、uner can be obtained t he best sensitivity. (No . 1740) 9 tJ PC -V77 A /B/E/G/UN . Band Select Switch Position 13 14 15 SW 16 17 (A/U Version) Sort of Antenna to be attached to SSG Dummy Antenna Frequency of SSG Preset Memory No. Aligning Position 17.9MHz M5 L6 Turn L6 until the voltage of TP9 becomes 4.40.02 V . 6 MHz to be received 6 MHz L4 17 MHz to be received 1 7 MHz TC -4 18 Adjust the above aligning position (L4 & TP-4) repeatedly so that th