Akai-XV-tape-sm 电路图 维修手册.pdf

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1、RadioFans.CN 收音机爱 好者资料库 TABLE OF CONTENT Page I SPECIFICATIONS . . . . . . . . . . . . . . . . . . 1 II MEASURING METHODS . . . . . . . . . . . . . 2 III CONTROL LOCATIONS . . . . . . . . . . . . . . 4 IV DISMANTLING OF TAPE TRANSPORT UNIT connect the audio oscillator directly to the distortion mete

2、r for measurement of the distortion factor of the oscilla tor. The required distortion factor may be obtained from the results of the above measurement by the following formula. do=d-d1-d2 where, d0=Requred d=Overall distortion factor d1 =Noise level d2 =Distortion factor of the oscilla tor (Note :

3、New tape of particularly good quality should be used for measurement of the distortion factor.) 5. POWER OUTPUT Playback the tape pre-recorded with a sine wave of 1,000 Hz at 0 VU, and connect an sn load resistor to the output terminais of the tape recorder : measure the voltage across the resistor

4、with the volume control set to maximum. Use the following formula to obtain the required output : E2 W=R Where, W . Output (watt) E . Output voltage R . Resistor (Sn) (Note : The sn resistor used in this measurement must be of high precision). 6. CROSS T ALK (Cross talk between the tracks) (TAPE) CD

5、 ( Tape direction ) w CD Tape dir ection As shawn in the figure, first record a 1 ,000 Hz sine wave on track No. 3 at + 3 VU level. Next, remove the 1,000 Hz input signal and record under a non-input condition. Then playback the tape on track No. 3 and No. 1 (reversed condition of tape) through the

6、1,000 Hz B.P.F. (Band Pass Filter) and obtain a ratio between the two from the following formula. Eo C = 20 log-(db) E2-E1 C=Desired cross talk ratio (db) E0= 1,000 Hz signal output level E2= 1,000 Hz cross talk output level E1 =No-input signal record level 7. FREQUENCY RESPONSE Audio X-V Frequency

7、A.T.T. Line Input V.T.V.M. Oscilla tor Line Output Connect the measuring instrument as shown above diagram, and measure the frequency response in the following sequence : RECORD: 1) Give a sine wave of 1,000 Hz to the Line Input of the recorder to be tested, through an attenuator from an audio frequ

8、ency generator. 2) Set the Start and Record Knob in to Rec position and adjust the line input volume so that the VU me ter needle indicates 0 VU. 3) Under the condition described in (2), lower the input 10 db by me ans of the attenua tor. 4) Record the spot frequency in the range of 30 Hz to 25,000

9、Hz from the audio frequency generator. PLAYBACK: 5) Set the Record/Playback Knob in to Play position. 6) Set the Speed Selector Switch on 7-1/2 or 3-3/4 position. 7) Connect a V.T.V.M. and 82 resistor across the speaker terminal. 8) Playback the tape previously recorded. 9) Adjust the output level t

10、o 0 dbm at 1,000 Hz as indicated on the V.T.V.M. by the range selector of a V.T.V.M. 10) conditions in (9) ; make a memo of output level and plot the value on a graph. Ill . CONTROL ONS Supply Reel Shaft-, Trad: Selector -, Head Cover-._ Fast Fonvard Button-. S tart B utton -. Stop Button-. Record B

11、utton-. . Re,ind Button-, 1 VU 1Ieter(Right)- VU Meter(Left)- Tone Control(Left)- Amplifier Switch/Volume Control( Le ft) Input Jack( Left) Input Selector- Volume Control(Right;- Input Jack( H.ight)- Tone Control(H.ight)- Tape Speed Selector- Battey Voltage Indicator Meter- Battery Charge lndicator-

12、_: Take-up Heel Shaft :.:=:-Heset Button -Index Counter -Tape Holder IV. DISMANTLING OF TRANSPORT UNIT =:JV REMOTE CONTROL SW-3 CONTAINED IN AC. PLUG SW-4 AC. SWITCH to AMP. SW-7 CONTAINED IN VOLUME CONTROL SW-8 MICRO SWITCH Fig. 1 Fig. 2 Fig. 2 1. ST ART MODE (Playback) As shown in Fig. 2, when Sta

13、rt Key (A) is pressed, all levers from (B) through (K), illustrated in yellow diagram, operate almost simultaneously. The Pin located on the tip of Lever (G) pushes SW-5 as shown in Fig. 3, causing the motor to rotate. Motor rotation is transfered to Pulley (J) by means of the Drive Belt. When Lever

14、 (I) of Take-up Reel Spindle is pushed in the arrow marked direction by Lever (E), it engages the Inner Wheel of Take-up Reel Spindle which is then pressed downward Fig. 3 to contact Pulley (J). The Take-up Reel Spindle rotates counterclockwise to take up tape. During other operation, the Pin on Lev

15、er (F) sets SW-6 to the open condition, as shown in Fig. 3, and pushes SW-8 (a rnicroswitch). As this time, when switch SW-7, which is linked with Volume Control, is set to ON, current flows to the amplifier through SW-7 10 g, W1 spring stretched to a leJgth of 43 mm. 1. ADJUSTMENT OF FL YWHEEL (RUB

16、BER-WHEEL) GAP (Fig. 2) 35 37 44-l.g ) flywheel shaft thrust plate at the upper :tthe _chassis (at the side of the head), so that 10rt10n of the flywheel shaft does not come . . .c. ontact wtth the upper mam metal holder . 1 ftt d 1 or decrease the number of nylon plates th 1 e 1 thrust plate undern

17、eath the chassis, so at the t 0 cal play of the flywheel becomes from 0.1 o .Sm. 6. ADfMENT OF BRAKE MECHANISM (Fig . Fig. 3 In the stop c d . th on Itl-1 e-2 -3 -5 -7 ; . 8 0 . 9-8 )-10 ) -1 Take-up Reel Shaft G-11 -12 -13 0 14 15 : - - e 0 8-29 8 16 17 -18 Fig. 4 a) Supply Reel Shaft The tension o

18、f the supply reel shaft is 10 g standard as measured by a stick gauge, provided that the tape is wound around a 3 reel in the playback condition, to a thickness of 40 mm, with the end of the tape curled into a ring. Adjust the tension by increasing or decreasing the tension of the mission spring Ci)

19、 of the supply reel shaft. b) Take-up Reel Shaft The tension of the take-up reel shaft is 30 g standard, measured in an identical manner as the supply reel shaft. Adjust the tension by increasing or decreasing the tension of the mission spring of the take-up reel shaft. (However, counter belt should

20、 be removed for measurement) 8. ADJUSTMENT OF HEIGHT OF REEL SHAFT (Refer to Figs. 4 and 5) . a) Adjustment of height of supply reel shaft Adjust the thickness of the height adjustment nylon washer after removing the supply reel shaft, so that the height from the surface of the mechanism chassis to

21、the top portion of the reel table plate is 32.3 mm in the rewinding condition. b) Adjustment of height of take-up reel shaft Remove the take-up reel shaft and adjust the truck- ness of the height adjustment nylon washer so that the height from the surface of the mechanism chassis to the top portion

22、of the reel table plate is 3 2.3 mm. Correct vertical looseness of the reel shaft by til ting the thrust lever . Supply Reel Shaft Take-up Reel Shaft Fig. 5 VIl. AMPLIFIER ADJUSTMENT 1. RECORDING BIAS VOLTAGE ADJUSTMENT V.T.V.M TR501 2$8324 TR502 258324 Connect the V.T.V.M. to point (A) and adjust t

23、he recording bias voltage by turning the V.A.C. in the bias oscillator circuit until it reads the same voltage stamped on the back of the head assembly. 2. RECORDING LEVEL ADJUSTMENT (Fig. 2) TR203 2SC281 TR204 2SC281 a. Set the Automatic Recording Switch to Manual position. b. Connect the V.T.V.M.

24、to point (A). c. Push the Record Button until it locks and set the Tape Speed Selector to 7-1 /2. d. Feed a 1,000 Hz sine wave signal (with 1.5 mV output level) from an Audio Frequency Oscillator to the Microphone Input of the X-V. e. Turn the Volume Control VR-la (lOK-A) until the output level at p

25、oint (A) reaches 0.9 V. f. Turn the Volume VR-201 (20K-B) until the VU meter indicates 0 VU. Fig. 1 Note : There is no erase bias voltage adjustment. Correct bias voltage is between 40 and 50 V AC. V.T.V.M 00 0 Fig. 2 3. A.G.C. (AUTOMATIC GAIN CONTROL) ADJUSTMENT (Fig. 3) TR201 0 SW-2a IN34A a. Afte

26、r adjusting the Recording Level as indicated in step (2) above, feed a 1,000 Hz sine wave signal (with 1.5 mV output level) from an Audio Frequency Oscilla tor to the Microphone Input of the X-V. b. Set the Automatic Recording Switch to the AUTO REC. position and turn the volume VR-202 (500 ohms) un

27、til the VU meter indicates 0 VU. 4. MAIN AMPLIFIER ADJUSTMENT (Fig. 4) (Adjustment of D.C. Collector Current for Power Transistors 2SB-370 with no input signal) 1.5k 100 a. Disconnect the wire between points (A) and (B) by using a soldering iron. b. Connect the D.C. AmpMeter (use one with Milli-Amp

28、Scale) to points (A) and (B). 5.6k 2SC828 Fig. 3 Caution: (1) When A.G.C. Switch is set to Automatic Recording position, the adjustment should be done after 30 seconds while C226 ( 4 70 JJ.F) completes the charging. (2) When Au toma tic Recording switch is ON, the power source is recommended to be O

29、FF. 33/10 D.C.AMMETER Fig. 4 c. Turn the Volume Control VR-1a back to the minimum position. d. Turn the Volume VR-401 (1 K ohms) until the D.C. AmpMeter shows 6 mA. 5. BATTERY CHARGING CIRCUIT ADJUSTMENT 2S8 370 X2 IN34A CHARG 1 NG LAMP 250mA 50mA-+- -:;.TIME a. Use a fully charged battery. b. Conne

30、ct the D,C. AmpMeter (use one with Milli-Amp Scale) to between points (a) and (b ). c. Connect the D.C. Volt Meter to points (c) and (d). d. Turn the Volume VR-501 (5 ohms) to the middle position. e. Turn the Volume VR-502 so that the charging circuit closes ( 5 ,., 7 mA) indicated on the AmpMeter)

31、as soon as the VoltMeter shows 7.5V. 2$8758 X2 VR501 5.n. c 6.3V l Fig. 5 Fig. 6 7mA Fig. 7 6. TAPE SPEED ADJUSTMENT TR3 + -+-4-_. _ _. _ -r-GV TR7 a. Connect the Frequency Counter to the Speaker Output Jack. b: Playback the test tape ( 1,000 Hz 0 VU recorded) at 7-1/2 tape speed and adjust the tape

32、 speed by turning the Volume VR-1 (SK ohm) until the Frequency Counter indicates 1,000 Hz. Fig. B VIII. HEADS ADJUSTMENT 1. HEIGHT ADJUSTMENT (Fig. 0 Bias Voltage Fig. 1 Adjust Recording and Playback Head Height so that the upper edge of the left channel core is parallel with the upper edge of the t

33、ape, by turning the 2 set screws, as shown in Fig. 1 (a). Adjust Erase and Bias Head Height so that the upper edge of the upper Erase Heads core is 0.125 mm higher than the upper edge of the tape, by loosening screw (b ), and adjusting the cam up or down as shown in Fig. 1. Bias Head Height Adjustme

34、nt is automatically complet- ed witlr Erase Head Adjustment. 2. AZIMUTH ALIGNMENT Set the tape speed to 7-1/2 ips. Connect a V.T.V.M. to pre-amplifier output. Playback a 16 KHz recorded tape and adjust screw (f) of Fig. 2 so that V.T.V.M. indicator reads maximum. 3. ADJUSTMENT OF BIAS HEAD AND BIAS

35、VOLTAGES (Fig. 2) ,-t!hlf#l- L_ _ 0 0 ci Fig. 2 As Model X-V utilizes a Cross-field Recording System, each machine has its own optimum Bias Vol tage. The optimum Bias Voltage is indicated by a mark stamped on the right edge of the head assembly. Bias Voltage should be measured with a V.T.V.M. When t

36、he head assembly is replaced, adjustment of Bias Voltage to the same previous value will ensure a optimum recording condition. When replacing the Recording/Playback Head, adjust the space between the Bias and Recording Head to O. 3 mm by loosening screw ( e) and adj us ting the Bias Head stopper, as

37、 shown in Fig. 2. The space between Bias and Recording Head, and Bias Voltage should be adjusted to ensure a FLAT frequency response when the Recording/Playback Distortion Level reads within 3% at 1 KHz. IX. MAINTENANCE PROCEDURE LUBRICATION a. Parts to be lubricated 1) Upper and Lower Bearings of Flywheel Shaft 2) Pinch Roller Shaft 3) Fast Forward or Rewind Pulley Shaft 4) Supply ;z:; FRONT : allo- 1 CH1 CH2 lK-o-, 1 o;Qt BH R IGr HT. A B c : 1 1 1 1 1 1 1 ,- CSHOWING AMP. ON CONDITION) XS SCHEMATIC 1360&246