Akai-GX-635-D-Service-Manual(1) 电路图 维修手册.pdf

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1、 0 ;.j-i-ii;i s STEREO TAPE DECI( Mo,), GX635D SECTION 1 SERVICE MANUAL. I SECTION2 PARTS LIST. .43 SECTION3 SCHEMATIC DIAGRAM .67 RadioFans.CN 收音机爱 好者资料库 I. TECHNICAL DATA TRACK SYSTEM REEL CAPACITY TAPE SPEED WOW - I r r l o !.1 r;:,;r :;:r lHs t 1 , i o ! t. :.-:-. -,r:(-!J u F I l o a J 4 s ! r

2、? tJ:. :ln * 3 i T ql :l l= 11 |; ri+*:rBe LJ i3 g I r _ f $ f|e Lt Schematic-l STOP MODE -L . i :tl l j51 I t.E I t - l - * i -_,_l 6 o I d = r I l 1 - i t ii .*,ffit i* * ;:Tm! *A;1 - = ,-o -:-_.!;_ I tgv : , t o I r + r r . l l L j q ; - r + ; r ; + ; - ; J P F l3l :r; ,t:*f;U; * * i: .ffilMffitu

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5、 u, l 6- t4 Schematic-4 FWD-REC MODE I El , ! : r!: I 6 u t I Irl l ; A * Schematic-5 REV-REC MODE 15 ffi*e l t o - H r 3 i : . t I o t-s : i a;-*J t r,r .*:l - I I rlg l Tl6 i k . t G s ,lii :t !: t luu f El r,;i q .;,*. *. . ., itdh*ode ,m lft :r tunffi ii+, t ,1L-_.-l*E l , r l : o 1.2 ri:.1 s: l

6、3 , l ) i o N I ria I tdi L , - , . i j - - - u - - r , i I a tit : I l 3 i f i 3a! l ql Schematic-7 RWD MODE 17 I-I. CIRCUIT CONSTRUCTION OF ICI M544IOP The design oi M54410P until now trad STOP, pt-nY. REC, FF, RWD, PAUSE and REC preventing AR as its input terminals. GX-635D circuit is constructed

7、 with FWD in place of PAUSE and REV in place of PLAY. Pause is controlled by a flip flop with a separate IC. l) Block Diagram ST T I I ) I -l 4 . , )7 - I I I FAST FF Fig. 4 M544l0P /. 1 I l 8 Terminal NameTerminal Function Operation input terminals STOPlnput terminal for stopping operation FFInput

8、terminal for fast forward RWDInput terminal for rewind FWDInput terminal for playback in the forward direction REVInput terminal for playback in the reverse direction REC-Input terminal for recording Control input terminal ARInput terminal for preventing recording Output terminals FASTTerminal with

9、H signal output during fast forward or rewind mode FFTerminal with H signal output during fast forward mode FVDTerminal with H signal output during forward playback mode REVTerminal with H signal output during reverse playback mode RECTerminal with H signal output during recording or REC/Pause mode

10、2) Terminals and their functions 3) Operation activated by each input NOTES: 1. The input signal is activated by the fall of _-f . 2. The output is maintained until the next input signal. 3. AR is a control input terminal and the REC output is not H when AR 4. When AR = L signal is supplied during t

11、he REC output is H, REC output becomes L. 5. At the moment the power is on, all output will be L and the Stop mode will be effected. 4) Regarding the input circuits diode Dl3 Previously M54410P has been so designed that the first terminal was FLAY input and the sixth terminal was PAUSE input. But in

12、 GX-635D, pLly is used for REV and PAUSE for FWD. Consequently, gounding only the 6th terminal (FWD) will not allow the modes to be changed Chart-2 Chart-3 directly from FF or RWD to FWD. For this reason, the first terminal (ngVt is also grounded through diode Dl3 releasing FF and RWD. In addition,

13、even if there are simultaneous inputs into both FtD and REV, FWD mode output is designed to take prioritY. lnpul Signal Output Output Mode FASTFFFWDREV REC STOFL LLL LSTOP Mode FFH HLL LFF Mode RWDHL LLL RWD Mode FWDLLH LL FWD Mode REVL LLH LREV Mode REC/FWDL LHL HREC/FWD Mode REE/REVL LLH HREC/REV

14、Mode t9 VELOCITY + PULSE WIDTH CONVERSION r 5 0 1 I-2. CIRCUIT FOR PREVENTING CLICK NOISE DURING TIMER RECORDING l) When the power is turned on for timer recording, recording must take place after the amplifier circuit is in full operation or else click noise will be recorded. Also when the power is

15、 turned off, Rec Final Mute must operate before the amplifier circuit ceases to operate o else click noise will be recorded. This circuit prevents such click noise from being recorded. 2) In ordinary recording, base electric curent flows to TR28 base through R89 and R90, and TR28 is ON. Therefore, R

16、ec Final Mute relay RLI re Amp P.C Board) connected to TR28 collector is operating to supply the signals to the recording head and the recording mode is effected. 3) When the power is turned ON at timer recording stand-by, base electric current is supplied to TR27 base only while C42 is being charge

17、d and TR27 is turned ON. When TR27 is turned ON, electric potential is not supplied to TR28 base and TR28 is turned off. Consequently relay RLI does not operate and Rec head is not supplied with a signal. Since TR27 turns off once C42 is charged, base electric current flows to TR28 base through R89

18、and R90. Because relay RLI function only after the ampli- fier circuit is in complete operation, the click noise is avoided. 4) TR20 and TR2l is OFF during recording mode and for this reason C32 and C33 are charged. When the power is turned off in this condition, by the charging voltage on C33 TR20

19、base will become lower than the emitter in electric potential and turns ON. TR2l is also supplied with electric current thereby and is turned on. When TR21 is turned on, C32 is discharged, and ICI terminal 2 (Stop-) becomes ground potential through D24. This releases the deck from the recording mode

20、 and the stop mode is effected. This operation takes place before the amplifier circuit stops and therefore the click noise is cut out. Fig.5 Block Diagram 2.THF. SAMPLE AND HOLD SYSTEM SERVO MOTOR (SCM-200) OPERATION l) Servo signals generally created proportionately to the number of revolutions of

21、 the motor are shown either as frequency deviations or voltage deflec- tions. The motor employed in GX-635D uses frequency deviation unaffected by time constants, etc., of the load circuit as input signal to the motor drive circuit through pulse width conver- sion. This pulse width varies proportion

22、ately to the deviations in the number of motor rotations. The deviation is detected, converted to a voltage value, is held at that voltage until the next servo signal pulse, and then impressed into the motor drive circuit. Meanwhile, since it requires a holding circuit and because 112 pulse are gene

23、rated for each motor rotation, time constants of circuits coming before the Sample and Hold circuit can be greatly reduced compared to the conventional voltage deflection detection system. For the reasons above, it features quick response to motor revolutions, minimum influence by tem- perature, and

24、 fewer chances of faulty mechanism. In addition, due to the inclusion of the servo voltage holding circuit, ripple content of the servo voltage holding circuit, ripple content of the servo voltage has been sharply reduced to result in a smooth and stable tape transport with a minimum of wow *l r. I

25、I t ( lo t: lrRro * / = tn T _ I -O- AADE qE ry L D9 -1 r. I TR4 R4 220 t5 2,?K e I 9 l ! cro ooil .-r- :+ _2 .E : TR5 = l I a8. , 3 : ( TR7 i ( ; q IR r 3 I I : E K i n L_ TR13 trt _ _ J t - _. R6 9 j x r K 8 2l Fis.7 (j) TR12 COLLECTOR 2) Explanation of the circuit operation (Refer to Figs. 6, 7)

26、The velocity signal obtained from the motors frequency generator is shaped into a waveform in the period of T proportionate to the velocity as in (a) on collector TR6. This signal is differen- tiated and enters TR7 base. This makes TR7s collector output as in (c) and turns ON TRl0 during the time of

27、 the negative pulse. Meanwhile TR8 base is supplied with a waveform like (d) and when it reaches the threshold level, TR8 is turned on. A waveform (e) with pulse width 11 is obtained from the collector. During the time T that TR28 is ON, TR9 base electric potential decreases to turn ON. Consequently

28、, TRI I base electric potential inreases and TRI I is also turned ON for the time tr . When the period T varies with the velocity, the pulse width t1 varies according to TRSs threshold level. But when TRl0 is on, it is con- stant due to the time constant. So that by using the period that TR is ON as

29、 the standard pulse, the pulse width t2 is constant regardless of the velocity. (g) and (h) show the ON and OFF condition of TRl0 and TRll. When the electric charge that was charged to C16 is discharged during the time TRl I is ON t1, a signal voltage of e propor- tionate to the velocity can be obta

30、ined. Next, with e as its basis, Cl6 is charged during the limited time of the standard pulse width t, , and by the charging voltage e the charging is stopped. The voltage is then held until the hext standard pulse. This voltage e is supplied to the TRl2 base and a servo signal E is obtained. This s

31、ervo signal E controls TR13 and drives the motor. As shown above, since tt and t2 are small, servo signal ripples are made small and a near direct current servo signal is obtained. In addition, the time constants of the smoothing circuit can also be made small that phase lag factor can be minimized.

32、 22 VI. MECHANISM ADJUSTMENT ADJUSTING WASHER (U TYPE) IENSION IVICRO SWITCH ADJUSTING WASHER (U TYPE) 1. GUIDE ROLLER LOOSE PLAY ADJUSTMENT (Refer to Fig. 8) Adjust the stopper (roller pulley on the right) screw (d) so that the loose play gap is approximately 0.1 mm when the guide roller is moved a

33、s indicated by arrow mark in Fig. 8. 2. TENSION MICRO SWITCH POSITION ADJUSTMENT (Refer to Fig. 8) Adjust the screws (e) so that the gap between the arm cam and the micro switch is approximately 0.5 to 0.8 mm. Check that the micro switch works and that the arm lock smoothly disengages. Fig.8 Roller

34、Block 3. ROLLER BLOCK HEIGHT ADJUSTMENT (Refer to Fig. 8) Use the U type adjusting washers for screws (u), (b), and (c) to adjust the roller block height: the distance between the tape guide center to the chassis board should be 43 mm. NOTE: Steps I and 3 also apply to the right guide roller. Z) 4.

35、REEL TABLE FIXING SCREWS Fig. 9 REEL TABLE HEIGHT ADJUSTMENT (Refer to Fig. 9) I ) Temporarily screw in the fixing screws leaving a gap of 15 mm between the reel table and the chassis board. 2) Run the tape and adjust the height of the reel table so that the tape is taken up in the center of the ree

36、l. Tighten fixing screws. Adjust the height of the right reel table at fast forward. of the left reel table at rewind. FIXATION NUT ADJUSTMENT SCREW L- Fig. l0 5. CAPSTAN SHAFT LOOSE PLAY ADJUSTMENT (Refer to Fig. 10) Adjust by turning Adjustment Screw to obtain a 0.1 to 0.2 mm degree of loose play

37、when the capstan shaft is moved as indicated by the arrow mark. Tighten fixation nut to maintain optimum adjusted condition. . A L- BRAKE MICRO , * swtTcH o 55os !5og BRAKE LEVER Fig. 12 ERAKE LEVER Fig. I I Fig. l3 BRAKE BAND POSITION ADJUSTIENT AND BRAKE TENSION ADJUSTMENT (Refer to Figs. 11 to 13

38、) 1) Adjust the brake lever to 180 position by loosen- ing the screws (a) and (a). 2) Work the brake plunger to check that the brake band is not slanted. 3) Adjust the position of the part with screws (b) and (b) to obtain a brake tension of 550 1 50g on both brakes at stop mode. (Use a 10009 spring

39、 gauge for a reel with 60 mm diameter of tape.) In case the specified brake tension cannot be obtained, connect the springs to the other holes on the brake lever and adjust. 4) By working the brake plunger with a finger, adjust the position of the microswitch screw (c) so that the gap between the br

40、ake lever and the micro- switch body is 0.5 to 1.0 mm. 6. E IL 25 sYs.coN Pc TH - r0t5 10. TAPE SPEED ADJUSTMENT (Refer to Fig. 16) Set the Tape Speed Switch to7-l12 ips and playback the I ,000 Hz,7 -l 12 Test tape. Connect a frequency counter to LINE OUT and adjust VR2 50 kB until the counter reads

41、 1,000 Hz !0.5%. Next, set the Tape Speed Switch to 3-314 ips and adjust VRI 50 kB until the frequency counter reads 500 Hz t0.5%. VR2 sOKB (7-l/2in) VRI 5OKB (3-3l4in) Fig. l6 27 VII. HEAD ADJUSTMENT TAPE GUIDE HEIGHT ADJUSTMENT NUT ERASE HEAD E4-241 RECORDING HEAD R4-241 PLAYBACK RECORDING HEAD HE

42、AD P4-241 R4-241 ERASE HEAD E4-241 Fig. 17 28 StepAdjustment Item Test Tape Supply Signal Mode Adjustment Point Remarks Tape Guide Height OptionalFWD Tape Guide Height Adjustment Nut 1) Adjust so that tape travels smoothly and does not twist. 2) Do not thread tape over tension arm. 2 FWD Recording H

43、ead Height OptionalFWD (a) (b) (c) Upper edges of Left Ch. head core and tape are the same height. FWD Erase Head Height Confirmation OptionalFWD Upper edge of Left Ch. head core is 0.1 mm higher than upper edge of tape. 4 FWD Playback Head Height OptionalFWD (d) (e) (f) Upper edges of Left Ch. head

44、 core and tape are the same height. FWD Playback Head Azimuth Alighment 8,000 Hz 3-3l4 ips Test Tape FWD(f)Maximum output, both channels. 6 FWD Playback Head Angle Alignment 9,000 Hz 3-3l4 ips Test Tape FWD(h) Adjust head gap surface so that there is no change in output level when tension is applied

45、 to the supply reel side. 1 FWD Recording Head Azimuth Alignment Scotch #2ll Tape 15,000 Hz -20 dBm REC(c)Maximum output. both channels. 8 FWD Recording Head Angle Alignment Scotch #211 Tape 15,000 Hz -20 dBm REC(c) Adjust head gap surface so that there is no change in output level when tension is a

46、pplied to the supply reel side. NOTES: l. Chart-4 As perfect head adjustments ae vital to tape deck performance, be sure that these adjustments are carried out properly. Be careful not to use a magnetized driver or other magnetized tools in the vicinity of the heads. Use only new tape as level varia

47、tion is likely to occur when using old tape. Demagnetize heads with head demagnetizer before and after head adjustment Set tape speed to 7-1 l2 ips. Adjustments outlined in Chart 4 are only for FWD side heads. However, adjustments for REV side heads are exactly the same. 2. J , . 5 . 6. 29 VIII. AMP

48、LIFIER ADJUSTMENT TC2 TCrb rczb FWD Playback Level Adjustment REV Playback kvel Adjustment VU Meter Sensitivity Adjustment FWD Recording Level Adjustment REV Recording Level Adjustment FWD Frequency Response Adjustment (331a in) REV Frequency Response Adjustment (3-3la in) Frequency Response Adjustm

49、ent (7-l12 in) Bias Filter Adjustment V R I I I V R 2 VRIb VR2b Fig. l8 VR3 VR4 VR5 VR2 VRI TC2 TCI VR7 L3 50 kB 50 kB l k B l0 kB l0 kB 80 PF 80 PF 30 kB * The letter b following an adjustment part number indicates RIGHT CHANNEL 30 Step Adjustment Item Test Tape Supply Signal Mode Adjustment Point ResultRemarks I FWD Playback Level 700H2 7-l 12 ips OVU Test Tape FWD VR3 50 kB 0t0.5dBm (0.77sv) 2 R