Uher-4000ReportL-tape-bbc 电路图 维修手册.pdf

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1、UHER PORTABLE TAPE MACHINES BBC MODIFICATIONS with this change the facility for remote control via the microphone socket is omitted. 3. C32 and R46 are omitted, and capacitors and resistors are added in circuit, at the record/ playback switch preceding the output stage. This is in order that, in eit

2、her the record or playback mode, the output has a suitable rising frequency characteristic for transmission over a P.O. line. 4. A preset 1 0-ohm resistor is connected in series with the external loudspeaker socket, which is used to feed a P.O. line (via a coupling unit). This resistor is set in the

3、 output adjustment procedure so that a standard output, suitable for a P.O. line, is provided corresponding to zero level indication on the recording meter (with volume and tone controls set at maximum). The 10-ohm control is mounted inside the machine behind the external loudspeaker socket, or on o

4、ne side of the RADIO/PHONO socket. 5. A 750-ohm resistor is connected in series with the variable resistor R19 when it is a 1- kilohm control. This facilitates adjustment of R19 to obtain a standard playback output from a recording made on the machine (after the setting of the 10ohm control previous

5、ly described). On later 4000 ReportL machines, R19 is 2.5 kilohms and the addition of the 750 ohms resistor has not been necessary. 6. A ganged pair of changeover switchds is fitted so that adequate output is still available to the internal loudspeaker when it is used. The switches are operated by t

6、he shaft of the volume control. When the knob is pushed in, the added RC networks shaping the frequency characteristic for sending to line are short-circuited, and simultaneously output is fed to the internal loudspeaker instead of to the external loudspeaker socket. In the original circuit, one swi

7、tch shunts the internal loudspeaker across the external loudspeaker socket. 7. The switches in the standard Uher circuit that change resistance and capacitance values in the amplifier with change of speed are omitted; a link is fitted for the fixed speed of 19 cm/s. All the resistors and capacitors

8、required for apeeds other than 19 cm/s are omitted. 8. With the substitution of a 3pole socket in place of a 5-pole socket for the microphone, the facility for remote control is absent. The remote control relay circuit components are omitted and there is no conductor joined to connector 4 on the acc

9、essories (6) socket. 9. C28 and R33 are short-circuited to modify the recording frequency characteristic. 2 foo 1li ._ _ .,. _ . ,1 + 2 RADIO/PHONO 0 .B1 1 3 I rw et=-.;-l._ I T 2 R3 .C4 1M .,.200p I I I + . r p 1 - ,- - -, . 0 .Ea I . . I 33 K5 + I -3 R661) m- 220 T ?) 100 _.!L.,_ L,oo N!k 15k) I R

10、38 15k + + 0 0012: I r I r o . c.J 001 . +_j r- - . -.-. -. -. I I 0001 r C9 R18 10kl C15 -11-,-) I pf :33p I. = t 16 L _ ! il0 100p , # 6 I R11cord I - r 1o p 5 R25 T;., ) TT; 47k R2 fj 4701 3 1. !C20 i100 9 r-: C28 lfR33 =g oo68 47k R4_l tOOk . 1ok 0068 120 p +- ,Mi., 1o8k 181 r . p - 001 . R71 I

11、15k - - VOLUME R51 10k log : c35 01 R48 )- Tn I .!:,) I I? T5 BC214 I .A I R621 tOOk 181 ,: L _ I TONE + _+ _ _ _ j, -6 -t 4 . - -. - (!)SPEAKER l socket R22 5k l_ neg.log. J l REC LEVEL K2 + -7 - I Switches omittd I t-L-i-oo k -. i I c 22 = 0 0 0 0 . I 0012 C24 C27c61 j C109 R +I 22 1ok C117 T I I

12、fm:j ) I R106 1 JR111 R1.Q_ 100! R128 1k =C122 I 22k 2-2k .-r . -,._. -, 9 15k ;0033 C110 R115 R12 1 +. r- C25 r-11- C1,.3 5:6k -;c) c1 ._ _ _._ _ _. 22 .6 l R5 I 001 I 10k I c:, C138 I r log -._ 111 100 1Bk -._c-l _l I ()04 1 ! .1 =:. J : ,_,., 100 /1 1r Jf7 1 + cIJ 2 ;, -:!, ID-5 . -, :J 1 no; , 4

13、 7 T10 C115 I -l,-1 1 E3VI -) .-1 I J I f? Ljn._. 5k . T1Dj._ R140 R145 C13 1 .1. c14 5 T 6 I : I + I f. 47k 33k 330pc:;:; l I 2 22 ,r L 29 . ;b,; I L ,_ . l _j ,gJ r:= :;: ;:i,.: r 1.-+-1 4 7 k 1 k .1. r r ,B1. 27 L: R1-12,j 100k 0 . 47k h1 0k R153 J 10k I , lto g i G 680 c E_,_I I C14 4 r- _1 R156

14、 10 0 C 139 = C142 1 120 1 0.47 I p R107 ,:1J3 1 :, p p1 R12 . R_13_2 -+ J - r L _c- 1102-03f-_. - k -+ _u C108 391 116 1K R125 0 -0033 120 p PJ.-J-10_0_;- 1 -_ k crJ-_16_- -4-+ 2 - 2 - k -i+-E-+- 3 - 3 _ _ 4 _ 7 _ 0 _._5_ . -r-r-rlp _ _. t+ + I NOTES (1) c3 OCkCt N I :; L. - +- ; L: 2:0: :=-=-=-=-:

15、. -_ =-. =-_j Accoassorioas K4 (gand with K10l (rx;:;-:)11-.- Erasoa . + Hoaad 1 _ 1 I C102. I (JI TIO I 0005 .01l._IL-I-+- I R11 I %IF= . L _ R119 T108 R118 680k :loC116 0022 - KEi 1., 5 :_C124 jjj0022 R137 I 1k R147 47 C132 !._ 47 c:; 15k (p(4 0!, I -+-c/tr K7 - 6to75V C126 JD-. c$J 1t-1n -, l - -

16、AL 1 + 2 L-0-l . _ _j Fig. 3 Circuit of Uher 4000 Report-IC with BBC 7 modifications in 1977, (motor control not shown). Adjustment of Preset Controls on Machines with Modifications up to 1977 This is the procedure applied to 4000 Report-L and 4000 Report-IC machines with modifica tions made up to 1

17、977. Component reference numbers for the 4000 Report-IC are given, followed in brackets by numbers for the 4000 Report-L. 1. Switch the machine to the recording mode. On a 4000 Report-IC, set the ALC selector switch to 0. On a 4000 Report-L, set the input selector to its central, radio source, posit

18、ion. 2. Apply a 1-kHz signal at a level of -40 dB to connectors 1 and 2 (earthy) on the RADIO/ PHONO socket. 3. Adjust the recording level control to obtain an output of -1 dB between connectors 2 and 3 (earthy) on the accessories socket ( 6) when measured with an EP14/1 (or ATM/1) set to high input

19、 impedance (i.e. about 50 kilohms). 4. Adjust the meter sensitivity control R148 (R11), inside the machine, so that the recording level meter reads zero level. 5. Pull out the volume control knob. Turn the volume and tone controls fully clockwise. 6. Connect a 3.9-ohm load to the external loudspeake

20、r socket and adjust the 1 0-ohm internal preset control in series with this socket to obtain -11 dB across the load. 7. Turn the preset control R103(R4) to feed maximum bias to the recording head (i.e. set the control to minimum resistance). 8. Record a 1-kHz input for about 10 seconds under the con

21、ditions set up in steps 1 to 4, i.e. with the recording level meter reading zero level. 9. Play back the recording with the controls set as in step 5 and adjust the 1-kilohm preset control fitted in place of R122 (or adjust R19 in a 4000 Report-L) so that -11 dB is obtained again across a 3.9-ohm lo

22、ad at the external loudspeaker socket. 9 Adjustment of Preset Controls on 4000 Report-IC Machines with 1977 Modifications 1. Switch the machine to the recording mode, set the ALC selector switch to 0 (manual), and press in the tone control knob. 2. Apply a 1-kHz signal at a level of -40 dB to connec

23、tors 1 and 2 (earthy) on the RADIO/ PHONO socket. 3. Adjust the recording level control on the front panel to obtain an output of -1 dB between connectors 2 and 3 (earthy) on the accessories socket ( 6) when measured with an EP14/1 (or ATM/1) set to high input impedance (i.e. about 50 kilohms). Note

24、: As a rule, this should result in the recording level control being adjusted to about half its range of rotation. 4. Set the meter sensitivity control R148, inside the machine, so that the recording level meter reads zero level. 5. Pull out the tone control and volume control knobs. Turn both these

25、 controls fully clockwise. 6. In steps, increase the recording level control on the front panel, and readjust the 500-ohm preset control connected within the machine to the recording level control to maintain -1 dB at the accessories socket (corresponding to zero on the recording level meter), until

26、 the recording level control is fully clockwise. This is done in steps to avoid damaging the meter. 7. Connect a 4-ohm load (a 3.9-ohm resistor may be used ) to the external loudspeaker socket and connect an EP14/1 across this load. Adjust the 10-ohm internal preset control associated with the louds

27、peaker socket to obtain -13 dB across the load. Alternatively, plug a UN10/17 coupling unit into the external loudspeaker socket and adjust the 10-ohm preset control to obtain +2 dB across a 600-ohm load at the output of the coupling unit. 8. Turn the preset control R103 to minimum resistance so tha

28、t it feeds maximum bias to the recording head. 9. Using the same 1-kHz signal as before (i.e. giving -1 dB on an EP14/1 at 2 on the accessories socket), make a recording on tape on the machine for about 10 seconds. 10. Play back the recording with the tone and volume control knobs pulled out and tur

29、ned fully clockwise. Adjust the 1-kilohm preset control fitted in place of R122 so that -13 dB is obtained across a 4-ohm load at the external loudspeaker socket (or +2 dB across a 600- ohm load at the output of a UN10/17 plugged into the external loudspeaker socket). After the above adjustment proc

30、edure using 1 kHz tone, connect to the machine the micro phone that will normally be employed with it and readjust the 500-ohm preset control (previously set in step 6) as follows: 1. Check that the ALC selector-switch is set at 0 and that the front-panel recording level control is fully clockwise.

31、Ensure that the tone and volume control knobs are pulled out. 2. Operate the machine in the recording mode and, holding the microphone at a normal distance (say, 450 mm), readjust the 500-ohm preset control so that typical spoken passages cause the recording level meter to just indicate zero level a

32、t peaks of deflection. 10 Checking Frequency Response 1. Demagnetize the heads. 2. Play a BBC 19-cm/ standard frequency-response tape on the machine and measure the response at all frequencies into a 600-ohm load between connectors 3 and 2 (earthy) on the RADIO/PHONO socket. 3. Using a reel of new t

33、ape, make a recording on the machine at the same frequencies as on the BBC frequency-response tape. Feed the recording input, from an audio generator, to connectors 1 and 2 (earthy) on the RADIO/PHONO socket at a level of about -40 dB. Set the recording level control to obtain a reading of -12 on th

34、e meter of the machine with a 1 kHz input, then note the audio generator output and maintain this output at all the other test frequencies. 4. Replay the recording made in step 3 and measure the response as in step 2. Compare the results at all frequencies with those obtained when the BBC frequency-

35、response tape was played. A relatively poor output at low frequencies and an excess (up to several dB) of output at the higher frequencies is typical and is acceptable for the purposes to which the machine is put. As a rule, with the type of tape currently in use, the bias preset control (R103 in a

36、4000 Report le or R4 in a 4000 Report-L) must be set for maximum bias (i.e. minimum resistance) to prevent the response at top frequencies being too great. Checking Erase Voltage To measure the voltage across the erase head, use a meter that is suitable for reading up to 50 volts at 60 kilohertz. A

37、reading of about 35 to 40 volts should be obtained on a 4000 Report-L and a similar voltage, or slightly higher, on a 4000 Report-IC. 11 Motor Electronic Control Circuit The following description of the action of the electronic control circuit for the motor is provided as an aid to fault diagnosis.

38、lt applies to the Uher 4000 Report-IC and the 4000 Report-L: the component reference numbers for both are given, with those for the 4000 Report-L shown in brackets. A diagram of the control circuit is given in Fig. 4 for reference. When the machine is switched on for recording or playback, the suppl

39、y is fed to motor windings W1, W2 and W3, and also to the emitter of T307(T16). The base of T307(T16) is positively biased through R311(R52), R312(R53) and R314( R56), so that T307(T16) is switched on and passes the supply to T301 (T10), T303(T12) and T305(T14) collectors. The bases of T301 (T10), T

40、303(T12) and T305(T14) are each connected to one of the contacts of a mechanical distributor, which is coupled to the shaft of the motor. Two of the bases are always earthed through the distributor, while the third is not earthed. In the circuit diagram, the base of T303(T12) is not earthed and is c

41、onsequently biased on via R302(R30) and R303(R32). As a result, T303(T12) switches on T304(T13), allowing current to flow through motor winding W2 and causing the rotor to turn. The rotor, in turning, moves the contacts of the distributor, removing the earth from T305(T14) ba$e and earthing the base

42、s of T301 (T10) and T303(T12). T305(T14) is now biased on, thus switching on T306(T15), and current flows through motor winding W3, causing the rotor to continue to turn. The earth is now removed from the base of T301(T10), current flows through W1, and the rotor continues to turn with increasing sp

43、eed. The mechanical distributor disengages at 1,250 rev/min and its function is taken over by RC networks C301 (C21 ), C302(C25) and R303(R52); C303(C31), C304(C33) and R306(R45); C305(C34), C306(C36) and R309(R50). The switching of the motor drive transistors T302(T11 ), T304(T13) and T306(T15) pro

44、duces pulses of voltage at their collectors, and these pulses are rectified by diodes and charge up C307(C37) until it reaches the conduction voltage of the zener diode connected to the base of T307(T161. When the zener diode conducts, the postive bias on the base of T307(T16) is lowered, reducing t

45、he voltage supplied to T301(T10), T303(T12) and T305(T14) and so also reducing the current flow through the motor windings, so that the acceleration of the motor decreases. As a result, the motor is governed to a nominal speed of 3,000 rev/min. The governed speed is adjustable within 8 per cent by R

46、312(R53). A reduction in the supply voltage decreases the collector current of T308(T17), thus increasing the positive bias to T307(T16) base and tending to stabilize the supply voltage fed to T301 (T10), T303(T12) and T305(T14). As T308(T17) and T307(T16) function in opposition to one another, a degree of temperature compensation is also achieved. When the machine is operated in the fast forward or rewind condition, switch K2(K6) feeds the supply directly to R310(R57), bypassing the speed controlling transistor T307(T16). In the event of serious difficulty with the motor control circuit, a