JVC-PCV77-cs-sm 维修电路原理图.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 3 Remova

2、l 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 Exploded View of Speaker Box and Parts Lis

3、t . 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 RadioFans.CN 收音机爱 好者资料库tJ PC-V77 A/B/E/G/

4、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 authorized in writi

5、ng 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 the manufacturers w

6、arranty 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 visual inspection nor

7、 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 such features are i

8、dentified 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 . The leads in the p

9、roducts 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 and dress should be

10、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, knobs, metal cabine

11、t, 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 Tester, measure the

12、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 line cord directly into

13、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 voltage across the resist

14、or 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 voltage measured must no

15、t 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 RadioFans.CN 收音机爱 好者资料库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 Loca

16、tion of Main Parts Main Board -AssV 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. Remove t

17、he 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 securing the

18、 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 assy 1)

19、 Remove the wire connector for the tuner board. 2) Pull out the board assy. 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 two scre

20、ws 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. Then remov

21、e 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 replaced. M

22、echanism Section (Top View) (Bottom View) t-L-V / A /t;j/t:./u /u/v Free se e manuals 3 Gralis schemas . -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 side. Then remove t

23、he 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 roller 1) Remove t

24、he 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 FF 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 from the mechanical

25、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 remove. Chassis removal

26、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 assy 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 Main Adjustment Amplif

27、ier 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 & flutter Playback output level Confirming playback frequency response Recording bias frequency Rec/P

28、lay frequency response Rec/play output adjustment (from battery) AUX 8 dBm, MIC 48 dBm Speaker 0 dBm/6 n Headphones 0 dBm/32 n Tape used Adjustment/check method VTT703 Maximize outputs of decks A and B; adjust to (10kHz) minimize phase difference between left and right channels. To adjust deck A, ad

29、just 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 VR851 . 2. Check if Dec

30、k 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 , TP251 and TP751 are -21

31、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 a 100 ) resistor in series

32、 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. (TS-8) Adjust VR 121 (L ch) an

33、d 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 setting Adjustment location Tape/norm

34、al 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 : VR222 L ch : VR 121 R ch: VR221 (No. 174

35、0) 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 VR121 RECORDING GAIN Adj. VR221 I JE=R ,i IVR 102 DEACK lA PLACLEVEL -iD PLAY BACK LEVEL Adj Id) Lf-D VR10l r-JLVR=202 _ IDECKIA SPEED Adj Tuner Alignment BASIC CONDITIONS REC/PLAY POWER SOURCE OF THE RECEIVER LOAD

36、 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 RESPONSE Adj VR2225c;oB 0 BIAS FREOUENCY Adj V

37、RI22 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 Minimum gain position Center position Near the m

38、inimum 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 to TP7 1-3 Aligning position: CFT, T2 1-4 Alignment (Waveform): Adjust AM I.F.T. (above mentioned aligning positi

39、on) 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 Description 2. FM IF ALIGNMENT 2-1 Conditions of the receiver

40、(1 ) Power source: Same as mentioned in item 1-1 (2) Function switch position: RADIO (3) Band select switch: FM (4) Volume control: Minimum gain position (5) SEA control: Center position (6) Variable capacitor: Near the minimum capacity position where no signal come in. 2-2 Connection of Sweeper and

41、 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 resistor (100 km in series to the positive side cabl

42、e 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 following figure. NOTE The discriminators CF is yellow. Adjust

43、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 item 1-1. (2) Function switch position: RADIO (3) Volume control:

44、 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) Output level of the attenuator in SSG: Approx. 50 mW 3-3 Power ou

45、tput 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 becomes 4.40.05 v. 3 or MW 4 600 kHz to be received 600 kHz (M2) L3 5

46、 ( Adjustments after AM(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 obtained the best sensitivity. 7 281 MHz M5 L6 8 Loop Antenna Turn L6 until

47、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 (M5) TC-4 12 (B/E/GIV Adjust the above aligning position (L4 & TC-4) repeatedly so Version) that the tuner can be obtained the best sensitivity. (No. 1740) 9 tJ PC-V77 A/B/E/G/UN

48、 . 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 1

49、8 Adjust the above aligning position (L4 & TP-4) repeatedly so that the tuner can be obtained the best sensitivity. Item Description 4. FM RF ALIGNMENT 4-1 Conditions of the receiver. ( 1) Power source: Same as mentioned in item 1-1. (2) Function switch position: RADIO (3) 8and select switch: FM (4)

50、 Volume control: 50 mW (5) S EA control: Center position (6) Variable capacitor: Refer the following list shown in item 4-3. 4-2 Condition of FM SSG. (1 ) Modulation: Refer the basic condition (2) Frequency: Refer the following list shown in item 4-3. (3) Output level of the attenuator in FM SSG: Th