Tandberg-TD20A-tape-sm维修电路原理图.pdf

TANDBERG TD 20 A-SE Circuit Diagrams and Alignment Instructions RadioFans.CN 收音机爱 好者资料库 Electrical adjustments TD 20A-SE Make the adjustments in the order in which they are listed here. Many of the adjustments require that previous adjustments have already been correctly made. Clean and degauss the tape path before and after adjustments. lt is assumed that the tape path has already been correctly adjusted as described in the Service Manual for the TD 20A, part No. 714127. Maxell UD XL or equivalent tapes should be used for recording. Necessary equipment - d.c. voltmeter. - 2 high impedance voltmeters (do NOT use universal meters). - Frequency counter. - Audio generator. - Distortion meter. - Wow meter (required for wow test only). - Test tapes: No. 2 - Azimuth adjustment playback head, 15,000 Hz,7/z ips. No. 3 - Playback cule, DIN 19H,7%ips. No. 4 - Playback level adjustment, 4OO Hz, 7% ips. No. 11 - Speed check, 1000 Hz, 7%ips. Bias Adjustment (front panel) Before adjustment, make sure that the Bias Adjust- ment potentiometers on the front panel are in the mid-position. Checking the oscillator frequency Connect a frequency counter directly to the record head. Adjust the frequency to 123.5 kHz in stereo recording with C313 on the logic board. Then check in mono, left and right, that the frequency are within !.2 kHz. lf outside the tolerance, adjust C303, DUMMY LOAD ADJ. on the audio board. Then check the frequency in stereo and mono left and right. Checking the Bias Adjustment (front panel) Connect an audio-generator to LINE 1. Start stereo recording at7%ips speed of a22kHz signal 30 dB below normal recording level (0 dB). Set the Monitor switch to Tape. Check that the output level measured with a.c. voltmeters on the LINE OUT are within approximately + 3 dB to - 5 dB when turning the Bias Adjustment potentiometers. Adjustment of EOT/BOT sensor To be performed without tape. Measure with a d.c. voltmeter on pin 3, contact 412 on the logic board. Adjust R422 (on the logic board) to 1.2 V reading on the voltmeter. A , 4 Test Adjustment No. or check Test tape Set the No. deck to Measuring tnstrument Measure atAdjust Correcl readinoSpeedComments 1.1 Azimuth, playback head 2 Playback. c,-r:-.:-. LquoI4oLrvrr. Normal. voltmeters LINE OUTAzimuth screw, playback head Maximum output, see comments 7% iosMaximum output or best compromtse. 1.2 Playback curye DIN 19H 3 Playback. Equal ization: Nomal. a.c. voltmeters LINE OUTPlayback E.Q. adj. R501 /R601 +2dB at 18 kHz 7% ips.Playback curue, DIN 19H, The tape contains the following frequencies: 1000 Hz (reference) 18 kHz, 15 kHz, 10 kHz, 4 kHz, 125 Hz, 40 Hz 1000 Hz (ref.). Ad.iust R501/R601 to + 2 dB at 18 kHz. 1.3 Playback tNet 4 Playback. Equalization: Normal or Somial a.c. voltmeters LINE OUTPlayback level R I 69/R269 0.9 volt7h ips. 1.4 Speed11 Playback.Frequency counter LINE OUT! o.5/. 995-1005 Hz in 7% ios. Test taoe No. 1 1 * is recorded at 1000 Hz in 7% ips. Test tape No. l 1 is supplied on a small reel. This test tape should be spliced into a tape on a larger reel al RadioFans.CN 收音机爱 好者资料库 Tes No. Adiustmenl or check Measuring instrument Measure at Set the deck to Monitor switch ioProcedure 2.1Bias pre-adjustmenvoltmeters LINE OUTRecord. Speed: 7% ipl Equalization: Normal. TapeConnet an audio-generator to LINE 1. Set the generator to 1Z.b kHz 30 dB below normal r*ordjng level (0 dB). Adjust RlSl and R251 to maximum outour level. Then turn R151 and R251 counter clockwise to - 2 dB from maximum readino. 11 Azimuth, rsord head a.c. voltmeters LINE OUTRecord. Speed: 77: ip: Equalization: Normal. Tape Connst an audio-genemtor to LINE t. Start rcording at 7% ips. of a 10O0 Hz signal 30 dB below normal recording level (O dB). Use the voltmeter readings as reference level. Then rmord a 25,000 Hz signal and turn the azimuth screw on the record head to maximum reading or best compromise on the voltmeters. 2.5Record/ playback curues voltmeters LINE OUTRecord. Speed: 7% ips Equalization: Normal. TapeConnst an audio-generator to LINE 1. Start rmording of a 1000 Hz signal 30 dB below normal recording level (0 dB). Use the voltmeters readings as reference level (0 dB). Then turn the generator to 12.5 kHz and adiust R151 and B25l to 0.5 dB from the reference level. Turn the generator to 25 kHz and adjust R139 and R23g to 0 dB. Check that the output level do not deviate more than J 2 dB from 20 Hz to 25,000 Hz. Record/ playback curyes voltmetem LINE OUTB ecord. Speed: 15 ips. Equalization: Normal, TapeUse the same recording level as in test 2.3. Use the voltmeters readings as reference level. Check that the output level do not deviate more than 1 3 dB from 20 Hz to 30.000 Hz. Adjust if necessary with PLAYBACK E.O. ADJ. B5O1/8601 and,/or BIAS ADi. R151/ R251. lf re-adjustment is done, check once again that the output lwel in 7% ips, Equalization: Normal do not dwiate more than r 2 dB from 20 Hz to 25,000 Hz. Adiust if necessary with R139/R239. Record/ playback curyes voltmeters LINE OUTBecord. Speed: 15 ips. Equalization: Special. fapeUse the same recording level as in test 2.3. Use the voltmeters readings as reference level. Turn the generator to 30 kHz and adjust R135/8235 to 0 dB. Chek that the outDut level do not dwiate more than i 2 dB from 20 Hz to 30.000 Hz. 2.6Record/ playback curues a,c. voltmete6 LINE OUTRecord. Speed: 7% ips Equal ization: Speria l. TapeUse the same rffording level as in test 2-3. Use the voltmeters readings as refereance level. Check that the output level do not deviat more than i 2 dB from 20 Hz to 25.000 Hz. Source,/ Tape a.c. voltmeters LINE OUTRecord. Speed: 7% ips Equalization: Normal. Source/ Tape Connect an audio-generator 1000 Hz to LINE 1. Adjust in Source with the Input Levels to 0.6 V on the voltmeters on the LINE OUT. Set the deck to stereo recording 3nd set the Monitor switch to Tape. Then adjust R142 and F.242 so that the level reading is 1 dB higher on the voltmeters. 2.6Program meter adjustment voltmeters LINE OUTSpeed: 7% ips Equalization: Normal. SourceConnect an audio-generator 1000 Hz to LINE 1. Set the Monitor switch to Source. Adiust with the Input Levels to 1.5 V reading on the voltmeters. Then adjust the program meters to 0 dB with R158 and R258 (Output Left and Right on maximum). 2.9DYNEO level adjustment Program meters LINE OUTSpeed: 7% ips Equal ization: Normal. SourceConnect an audio generator to LINE 1. Set the generator to 1 kHz. Adjust with the input levels to - 3 dB on the program meters. Then set the generator to 1 8 kHz and set the program meters to + 2 dB with the oYNEQ SENSITIVITY ADJ. (on leit side of the chassis). 2.1C Distortion voltmeter/ distortion merer LINE OUTRecord. Speed; 7% ips Equalization: Normal TapeConnmt an audio-generator at 1000 Hz or the distortion meter generator to LINE 1. Record to 0.9 V reading on the voltmeters and read the distortion on the LINE OUT Distortion maximum 0.5%. 2.11Wow and flutter Wow and flutter meter LINE OUTRecord.TapeConnet the wow and flutter meter to LINE 1. Read on the LINE OUT in highest and lowest speed: 3% ips. 7%ips. 15 ips. Wow and ilutter maximum: Weishted RMS OJO% 0.05% 0.m% Peak value DIN 45500 P.4. O.14y 0.08% 0.06% OSC. FREO. ADJ. IS ON THE LOGIC 8OARO. PLAYBACK EO. ADJ. IS ON THE PLAYBACK AMP. BOARD. LR aa R15r R25t BIAS ADJ, OUMMY LOAD ADJ, a c303 ; PLAYB. R169 L LEVEL B .METERADJ I qrqn R269 - REC. LEVEL L Ra a Rt42 R242 R REC. EQ. ADJ. aaL i|ffl?:i n,?sn?rs -oi. 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L I I ni- 6 I oT- a I l*l; I T: I swlTCH i: CtOl 0lC6 PART oF LoGtc BoARD NoEOat- - - - I l23kHz BIAS/ERASE OSC. lo.oo I I or2 | 1.t12 Audio Diagram FrcI LOGIC HL PLAY/FASI WINO/FREE L L ALL OHEF XOOES REC. AMP i -tii.:rTIi TrJ L5J.-JL_J5 li EOUAL.PLAYB. AMP PART OF BOARD NO.63607 A z. o (D I (J - = a T 4 D -l_ t; t: I I J 3f, t- !r3ol-r? R?70 c?35 R2?l : i106 FRoM Lo6rc: -_-, _)_ LrrtPrsoF : :!. H L rN alr orqtR L tt MoDEs. PARI OF BOARD NO. 53607 BOOSTER, L.P FILTER D L.CH T t00i fiABG; 1 BoARD NO.63685 | ,/ERASEi5C-_loo o,o I ;-l )LtL z DUMMY LOAD FROMLOGIC AL PLAY/fW /FREf 2tz NICI NTCI 56k 2 ?OR 2-M 220R roii 2t5 l2 0r rk5 a2t rwg 33oR 32R 32k Tandberg The European Alternative Tandberg A/S Fetveien 1, P.O. Box 53 o a-E c o - E o o -o o E z ; o c I r s r z o O- r r N-2007 Kjeller, Norway A