tandberg tcd-340a-circ-alignm 维修电路原理图.PDF
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1、TANDBERG TCD 34OA- Circuit DagraTs wrth A li gnrn en tTn st r u cti o n s Mechanical adjustments, see Service Manual for TCD 330, Ordering No. 714021 Electrical adjustments for the TCD 3404 General Before adjusting, the tape path must be cleaned and demagnetized. It is necessary that the tape path i
2、s correctly adjusted, consult the service manual for the TCD 330, part No. 714021. Carry out the adjustments in the order described because the adjustments affect each other. Remove the top panel, base panel, and right side panel. Equipment required - 2 volt meters - Audio signal generator - Frequen
3、cy counter - Distortion meter - Wow and flutter meter - Tandberg test cassettes - No. 21 (Speed check, 1000 Hz) - No. 22 (Wow and flutter check, 3150 Hz) - No. 23 (Azimuth adj. playb. head, 6300 Hz) - No. 24 (Playback level adj., 1000 Hz) - Measuring cassettes - Maxell UD XL I (Type I) - Maxell UD X
4、L Il (Type II) Before adjusting, set the buttons to: - MPX-FILTER (situated at the back of the deck) to OFF. - Dolby NR* to Off. - Tape to Type I. - Output Level controls to max. * The word Dolby is registered trade marh of Dolby Laboratories Inc., USA. NR stands for loise Reduction. Oscillator The
5、oscillator frequency is between 80 and 100 kHz. The voltage measured on the erase head should be between 25 and 32 volts. Sensitivity adiustment - Set the Monitor button to Source position, and Input and Output Level controls to maximum. - Apply 8mV,1000 Hz to the RADIO socket (DIN) or 80 mV,l000 Hz
6、 to the INPUT sockets (Phono) from the audio signal generator. - Adjust the SENSITIVITY ADJ. pots. Rl01-R201 to obtain 77 5 mY measured on a voltme ter con- nected to the Dolby encoder output, see Figure 1. - Move the measure probe to the Dolby decoder output, see Figure 2. - Adjust the SOURCE LEVEL
7、 ADJ. pots. Rl18- R218 to obtain 7 7 5 mV . - Check the frequency response in Source. Dolby encoder output Right channel meas.point Left channel meas.point _ | RroBP I Prosr. .:., P)lI P I RTL LLvtL TPf I TAPI REc METER J- - - -l R2rg R RrrB L R2oq Ra agrog ! aori*aa a?ura REc LEVL aoJ TYPE tl TAPE
8、TRIMMING POIS ON MAIN AOARD SEN FAOM SOLOER SIDE Figure 1 Trimming pots. and Dolby encoder rneasurement points Figure 2 Dolby decoder measurern,ent points Playback, azimuth Playback, height Record, azimuth Record, height Figure 3 Adjustments for the heads Azimuth adjustment, playback head - Insert a
9、 Tandberg test cassette No. 23 or a standard azimuth cassette. - Set the Monitor button to Tape and connect a voltmeter to each channel of the OUTPUT sockets. - Press the Play button. Adjust the playback azimuth screws shown in Figure 3 to obtain maximum reading on each channel. Playback level - Ins
10、ert test cassette No. 24. - Connect a voltmeter to each channel of the Dolby decoder output shown in Figure 2. - Adjust the PLAYBACK LEVEL pots. Rl19 and R219 until you read 775 mV on each channel. Level meter adjustment, playback - Insert Tandberg test cassette No. 24. When the playback level is co
11、rrect, adjust the level meter to 0 dB with PLAYBACK METER Rl14 and R214. Azimuth and height, record head - Use Maxell UD XL I or an equivalent tape. - Applf 1000 Hz to the INPUT sockcts both channels. - Set the Monitor button to Tape and connect a voltmeter to the OUTPUT sockets both channels. - Pre
12、ss the Record button and turn the two record head height screws shown in Figure 3 by equal amounts (the same number of degrees) to obtain the maximum reading on both channels of the OUTPUT sockets, or the best compromise. - Adjust the azimuth (10 kHz) and the height alternatively, until the head sit
13、s correctly. - Azimuth can also be adjusted with the built-in control oscillator (10 kHz). NOTE! The record height screws must be adjusted by equal amounts to ensure that the head paral- lelism does not change. Overall frequency response with Type I Tape (bias) - Set the Monitor button to Tape. - Ap
14、ply 1000 Hz from the signal generator to one of the inputs. - Re duce the level at the signal generator by 35 dB or reduce the level by a similar amount on the Input Level controls. - Press the Record button, and adjust the BIAS ADJ. TYPE I TAPE, C1502 and Cl602 to obtain maximum reading at the outp
15、uts. - Sweep the audio generator throush the full fre- quency range and check that the response curve is correct. - If necessary, adjust the curve with C1502 and C1602 to obtain the correct response, t 3 dB, 30 to 18000 Hz. -. Dolby decoder outpul Left channel meas, point Or measure on 81303 Right c
16、hannel meas. point Or measure on R1403 i . O ov Va .J n.: -v/- o-o Bias adjustments Adjusting the record current (Source/Tape) Distortion Type I Tape Record 1000 Hz at 0 dB deflection on the meters. I - Use the same input level as for the bias adjust- The max. distortion for record/playback is 3%. m
17、ent (- 35 dB) and 1000 Hz. - Adjust the record current by means of the Erase test REC. LEVEL ADJ. pots. Rl08 and R208 to obtain the same output level for both positions Connect a microphone to the TCD 3404 and on the Monitor butron. record an overload signal. Record again to erase the overload recor
18、ding and play back to ensure that - Then depress the Dolby NR button and check the overload signal cannot be heard. c the overall frequency response. Az imuth meter adjustment Overall frequency response with Type ll Tape (bias) - Set the built-in oscillator to ON. - Use the same procedure as for the
19、 Type I tape. - Set the Output Level controls to maximum. - Insert a Maxell UD XL II or an cquivalent tape. - Insert aType I tape and press the Record button. - Set the Tape button to Type II position, and / press the Record button. - Adjust p.Z2Z (AZIMUTH METER ADJ.) to - check the frequency respon
20、se, and if necessary, ff.or:r:t-tely - 3 dB deflection on the right adjust the BIAS ADJ. TYPE II TAPE, pot. Rl 508 to obtain the correct response. _ Check also that the meter deflection with a Type II tape is within the meter scale. Adjusting the record current (Source/Tape) Type ll Tape Speed check
21、 - Use the same input level as for the bias adjust- ment (- 35 dB) and 1000IIz. Play back Tandberg test cassette No. 21 (speed check 1000 Hz) and measure with a frequency - Adjust the record current by means of the REC. counter on the OUTPUT sockets: LEVEL ADJ. pots Rl09 and R209 to obtain the ! 03%
22、 (995 to 1005 Hz). same output level for both positions on the Monitor button. Wow and flutter R1101 and R1201 affect the treble response in I the frequency region 15-18 kHz on the playback Play back a Tandberg test cassette No. 22 curve forall types of tapes. (3150 Hz) and measure with a wow and fl
23、utter meter on the OUTPUT sockets: Level meters adjustment, record weighted RMS: ( 0.09% Weighted Peak DIN 45511 10.2% - Set the Monitor button to Tape Record/prayback - Apply 1000 Hz to the INPUT sockets (both Record from a generator 31b0 Hz (check with a channels) frequency .or,ni., and measure wi
24、th the wow and flutter meter on the OUTPUT sockets. - Press the Record button and adjust the Input Level controls for 1.5 volt ,.uiing on thi weighted RMS: ( 012% OL-rTPI-IT sockets. - Adjust the REC. METER pots. Rl13 and R213 to obtain 0 dB on the level meters. g Al , ! r- -l ; A4 EOUAL REC AMP (NO
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