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1、price $6.00 SERVICE MANUAL SCOTT 344C - 384 RECEIVER CD SC OTT-. whereinnovationisatraditio11 H. H. SCOTT, INC., 111 Powder Mill Road, Maynard, Massachusetts 01754, Tel. 617 897-8801 RadioFans.CN 收音机爱 好者资料库 Scott . where innovation is a tradition Price $1. 00 Ill H. H. Scott. Inc. 111 Powdermill Roa
2、d, Maynard, Mass., 01754 SPECIFICATIONS TUNER (FM-MPX) Usable Sensitivity (IHF) Cross Modulation Rejection Signal to Noise Ratio Total Harmonic Distortion Frequency Deviation (Drift) *Frequency Response Capture Ratio Selectivity Tuning Range Accuracy of Calibration Separation FM Remote-OFF OFF VOL 0
3、.5% 18-25,000 :!: l db 25-20,000 Hz 78 db 105-120V, 50-60 Hz 25-95 watts With negative lead of VOM to chassis, measure collector resistance Q2 4.l.JIDI TEST: = s-Silii 4. Distortion Check At 15.5V output max. distortion 0.6% (one channel operating). 5. Tape Monitor Switch gJR.M:Nisiv. -.2A0r-+-_, _
4、_,._ _ ._-+-+-1-1 ii,:i,oR. . R40 3.K 5o/ 2 -IM,-lD-BALA.NCE TEST Pon,IT. .,. ,., ,w 31 -CJI- BIA.5 TEST POINT. 1 . -+-t-0-SivJi,1 QI. ,. .,. . -0-;gS;TgT: . SW ,. :Ii 0 W.w 30 fr-0-PHONES -JA.C.K TIP C5 27 22pf IK ,a ,_ _ _ 40 r-+-BIAS OIOOE STRlG1 CATMOOE -+-ut-BIA.S OIOOE STRlt.JG, AWODE R.125 SG
5、 38 ,.-. -,-ttiGLl,SRc.i.oC: QI02. ,_ _ 0.,.-:;:lFsbuJfJJ Powe TO EMM ITEI OF OUTPUT POWER TRA,NSISTO Ql02 .-.v,2V10,-+-P-.-+-,-.,.,.-o-1 g_u;,:ioR . SK t.5% . -+-o . -;siTR. og; POWER .,.R_l3_8 _ _en-;giM4-Tiu;b1. -82 SW 34 . -Wr-.-t-9-.-1,-7- 4 -5-CJ-c:,iRurp6; FEEOSACK). 150 1;2w CIVr-Pf-ON$ -.JA
6、CK. TIP 43 -J NOTES; I. UNLESS OTHERWISE SPE.c1.=-1i:o. RES15TANCE IN OHM$ 10% , CAPACITANCE rN MF05., RESISTORS l/4 WATT, ALL vo . TAGES o.c. !IS ARROWS 01,J POTENTIOMETERS INOICATE. CW ROTATION :,_ ARR9W HE.ACS INDICATE MAIN SIGNAL PATHS. 4 SMALL NUMBOCQ.E.0 CIRCLES INDICATE T 48 TERMlfJALS AD THE
7、 TWO TIE POINTS ON THE POT TA.P OF LOUOJ!cSS CONTR.OL. 5 VOLTAGE GNI-JS :!:,ZdB AT fK.f-,1TION. TONE CONTROL-DRIVER Z-PC-TD-8 00 HIGHEST SERIE$ NUMBERS R.41 R.141 ue c11e DI 0101 LEFT RI T DRIVER OUTPUT TO TRANSISTORS (QP-8) TONE CONTROL_v 4 ,. . a o O ;t,c.O / if .ll-0 r.: n n+ ti! 1._7c116 e c C Q
8、lO bo QI . LINE SHOWS SIGNAL PATH THRU AUDIO SECTION OF UNIT (LEFT CHANNEL) ii.; 01, 0101 -2N2924 (OA-14) Q2, 0102 -2N2925, SE4010 0 3,0l03 2N3019 (OA-10) Q5,Q105 04, 0104 2N4033 (OA-17) DRIVER INPUT TI.JNER TEST 344-C FM TI.JNER SECTION EQUIPMENT REQUIRED H.P. VTVM Oscilloscope VOM Distortion Meter
9、 FM Generator (or source) MX Generator (or source) Audio Generator (or source) Set Controls to the Following: Separation Pots Input Select. Switch Muting Mode PRELIMINARY CHECKS Max CW FM OFF STEREO 1. Mono Alignment and Sensitivity Check Front End and IF Alignment With about 10 uV generator output,
10、 align and peak front end for max. output. With 3 uV input, align IFs for max. audio. With 1 or 2K uV input, align detector for minimum distortion. 2. Sensitivity and Distortion Measure sensitivity of tuner with 3 uV rf input. Must obtain 30 dB usable sensitivity at 92, 98, and 106 MHz. Recheck dist
11、ortion, 2k uV input. 400 Hz -max. distortion of 0.6%. Audio output 1.5V +2 dB 3. FM Hum Check Tune to 91.5 MHz, measure min. of 60 dB (may reverse ac plug) 4. De-emphasis Check Tune to 90 MHz (change mod. to 8 kHz), note decrease of 12+2 dB in output. 5. Calibration Check Check calibration against s
12、tations - max. tolerance 0+0.2 MHz. TUNER SECTION 6. Muting Adjust Tune to a point on the dial where no station is heard. Turn muting switch to ON. Adjust muting threshold pot to max CCW position, At this point noise will be observed at tape output jacks. Advance control clockwise until noise disapp
13、ears and then slightly further, check unit for switching between 10 ;:;tit . TH;I:1 = ,-,. :II? -U. Q2 .-./ . . INTERSTATION z,PC.,NS 3 NOISE MUTING 00 MUTING OFF-ON SW NOTES: f. UNLESS OTHERWISE. SPECIFIED: RESISTANCE IN OHMS :!IO?o CAPACITANCE IN MFDS RESISTORS 1;4 WATT 2. ARROW ON POTENTIOME.T:R
14、INDICATES C/J llOTATION 3 FOR USF WITH E:XiERNA;_ MUTING CONTROL WHEN RI IS NOT ON SOARO. HIGHEST SERIES NUMBERS C2 R6 Q2 + Cl 1/20 I 2J371 I I lil2N295 C2 .oz I 2 I G I L OK _J -INTERSTATIOt-J NOi SE MUTl)IJG Z-PC-NS-3 00 10 MUTING B+ FROM IF AMP MUTING OFF-ON SW MUTING CONTROLLED B+ TO Ir: AMP. 1
15、GND. 1777 . . F R NI T E NI D ,t,. I.ill I N M E N ill) lt , - w =cs, , FM FRNT END ALIGNMENT FR 344-C FM SECTlN l. Connect 1U generator to the antenna terminals with the following adaptations: FROM GEN. 270A 2. Set RF generator and FM tuning dial to 92 mHz. Generator output should be about 6 uv. Pe
16、ak L2Q5, L204 and L201 for maximum audio output. 3. Set generator and FM tuning dial to 106 mHz. Peak RF trimmer and mixer trimmer. 4. With about 3 uv from FM generator, repeat procedure until no further output is obtained. Signal should look like this: 5. The only time that the oscillator mixer and
17、 trimmer should be touched is if the calibration is out of specification. SEE PAGE 15 FR METER CIRCUIT MIX HIGH METER DRIVE MOW A RGOI 47K IF OUT 10,7MHz IF OUT 10.7MHz L.601 1.UH Mechanical layout of Front End denoting, sci I la tor, Mixer, Antenna Coi Is and Voltages present under nor- mal operati
18、ng conditions c e I IF i-;.;._-11_8_+_1_2_V _ _ 11 OSC.HIGH Q cen_.b 0 e04 OSC. LOW QRF2 Z-FM -15 -1-n FRONT END AGC r.rn4- rRi;J Ei;JD l .;, ;,/ +l2VDC. C212 R207 ?20 L205 :T0.7 NCIF C20 c210 C21.5 IS G2 10.7 MC. I-NPO G204- .001 G/202 L20f C201 C202 C203 GRF-2 R2l4 llK ro 1-10 NPO C20o I .001 C216
19、 I .005 TO FM _ .L _ - - - ANTLNNA 7 AGC - C2l7 +tl5 L206 .33_.t.th RZ09 I 220 C21IJ RZ/: HIGHEST rOOI 47 I SERIES L207 NUMBERS I R2/4 C222 czzs L207 1-10 C219 All voltages measured with 20,000 ohm/volt VOM; 300 ohm antenna and no signal. Q201 6 .025 D 9.2 S 1.05 Troubleshooting Guide Trouble Low ga
20、in No Output Q202 B ,45 E .05 C 10.8 Possible Remedy Replace Q2O1 Q204 B 3 E 2.6 C 10.2 Open LRFC 2.2 or .33 defective Q2O1, Q2O2, Q204 12 IC SECT! 0 l-J TROUBLESHOOTING PROCEDURE FOR I C-1 F-4 IC:301, IC:302, IC:303, C:304 -A703 +ti.BY OUT i !0.7MH:,-IN C3O1 oz $QUELCH N-lOMPX. S:IUFL:H 1-+lZV 1N I
21、 AGC ?J_JT _ x _ i_ -L- =-rs ye 7 0 G R302 K.303 -, I I m I I I L -n-.-c-+- C302 J. UOG - T 02 I n1, 7 I HIGH n,2 I .:. .,._ J 0 0 Z-Pc IF-6 )JOTES l. UNLESS OTHERWJSE SPE _ ,FIEO RESIST.q,JCL IN 0Hi-AS -t CA.PAC1T,A.t-JCE :1-J M;:-D3 RES1STOR_S 1/4 WATT VOLTS DC: 1$. MEASURED WITl-l 20K0./V.V-O -.I
22、I 2. ARROW -HEADS lND1CATE -MIN 51GNL PATH. -7 (tl.7V/ 20-.,._-+-o-+-1I,- I (12V) (L4VJ 3 ! I I I I 4 0 I METAL CAN uA70! rt0UYY 17 FLAT _ _,_ _ .,_,47tJ, -. 1, 1 GlSlill = ID:mil =flmll!I a:m:m. J L _ _ _ _ .! .tA703 (:1Q:lJlT Ct1Ac;i=;:,c:,.1,1 VOLTAGE CHECKS (UA703) Pin 1 B+ 12 Volts Set VOM on 3
23、 volt scale: No output or distortion Meter operates okay positive lead of meter on pin 1, negative lead on pin 2 and/or pin 6. If voltage is apparent, then that particular stage of IC is operating normally check diodes D303 and D304 for defect Meter Fegging either direction defective D301 or D302 13
24、 tvl.JLTIPl.EX Q1 2Nl924 QllN.2925 or SIE4010 or QA-15 Q3 2N3964 or 2N4249 or 2N42.50 Q42N3567 AUTOMATIC MULTIPLEX DEMODULATOR ZPCMX-14 TO -C2 _,-=m Ll /1:i+ lOmH INPUT 0 01 ,_,_-.,_ _ -+ _ ,vv,- 1i1l-ft0 G 04 PLED LE.FT I Cl4 R21 RIB :;c-f-Wlr-+-Wl-e-Nf-+-+- 68K OUTPUT .22/100 EcTI e SEPARATION 19
25、IOK GROUND 7 Jr, JUMPER 8 IOK I PEC-SIZ TO TERM.-4 ECTI 10 Clo RIGHT I 1 IOK IOK IOK D7 .22,/)00 OUTPUT- I 6rED SEPARATION RIS ,.,.-,-e-VV,-s/lA,-e-t- IOK .AUTOMATIC MULTIPLEX DEMODULATOR Z-PC-MX-14 NOTES: I.UNLESS 0THERVl1SE SPECIFIED RESISTANCE IN OHMS !OTo CAPACITANCE IN MFD5 REStSTORS 1/4 V-,A T
26、T. 2. ARRQv,.is ON POTENTIOMETERS INDICATE CIM ROTATION, 3 14 .AJMPER FROM TERM.8 3 _ _J LO INPUT LAP u, YQLTAGE UNlF.5$ QTH,a.,J1$1: $PECIFIE:D: ALL VOI.TGE$ P0$1TlVE DC: 15 9 MlaASLIR(O WlTI-I ?,OM.Sl/V VOM +117YAC: LINE 300 OMLOAC ON EXTERNAL ANUM!-IA TERMIMALS TUNl!/ii 011 SlATION -,I INPUT SWIT
27、CHIN-FM . PCISITIOO MOOE: $WITCH lNl.lONO POSITION. Ii VOLTAGE$ MEASUliEO UNOER S,_ME CONOtliONS AS ABOVE ONLY MOOE swm:;1-1 IN STEftEoPDSIT!ON WITH SltlUO SJ6NAL lEO INfO 1UNEn vo1.TAGE:S MEASuReo WITl(i.NAI., ll(ll!IIIVO.TAQ.ES ME:A5URE0 WITl-1 F!IUTING SWITCH INOrj POSITION,TUNER OFF STATION. Z-F
28、M-15 .ov 9-!V 1 .iv GIZOZ .V .lV -fiv 0204 z.asv e.asv 10.2v Z-PCIF61.EA0.1_ z s 4 .1. Jt_ :rc301 11.ev ,i:iv 1v Ov 1.av n.2v !C3!.!. 11.av 11.2V lkV ov ,.av 11.2v IC303 IU!V 11.2V l,(,V OV 1.8V 11.2V 1C304 1,2V 11.5V 1.55V OV l.(,V J2V lll*IC304 OV OV 1.S5V OV OV OV Z-PGNS-.:1 . _E c -o, 0o 0 v .I;
29、 g OV 14V QZ 13.SV 14 V 19 . W :-MXl4 n l4 ov 01 .-V 02 .sv 03 9V 0:4 ov Ql,QIO! ,2V a-e, 11102 z.sv .-.z-PC-TD-8 0.1 ,0.101 !.2.V QZ,0102. 4.2V Q3, Gll03 1.SV 04, Q!04 30V Gl.5, 0.10,5 32V +33 Q401 IZV 0402 12.v POWER TRANSISTORS ,GSV .,;tJy IOV -,2.v .eov .7V .2.V ,7V 4;?V ./o$V IOV Mv OV OV 33V e
30、.sv 4.4V 2.4V 30V 33V 12.7V 1:i.ev i,v V 30V .45V ,ov 34V 0.!,0101 OV . .5:5V 30V 0.2,QIOZ 29.SV 30V (;OV 0401 33V 33.!iV .54V AGC VQLTAGE -Z-PClF6J lEf?M 7 to. -1.-,vTo-1.ev WITH 1000.0V SIGNAL r=EO TO E)CTElcNAL ANTeNNA TERMINALS +lNPt.lT SWITCel IN.FM.POSJTIO!,/. R40Z R,;,oa C403 C-07 0402 Q,;04
31、Q401 FloOI TIOJ LGCZ + CLUTCHED WITl-1 IOtNTCAL CONTllOl.15 INTHI! RIQHT CHNNl!.L 6A!.S,111!UL, ANO LOUONl!IS. 6. 311 1, MECHANICALY GANGl!O WITH l.tUOt.1!115 CONTROL. 7. SI-INPUT SWITCH (SRw1t5-1J e-PHONO 3-FM 4-EICTRAl S-E:)l:TRAZ 8. SWITCH FUNCTION S l -INPUT 8.7 -VOLUME COhlP. se -TAPE se -NOISE
32、 J:ILTER S3-MOOE 59 -SPEAlelll!I MAIN S4 -SALANC 510-Sff:A112 R!NOTE S5-PREAMP SENS Sil -POwt!.fl 5G -FM MUTING , FI.FIOI -2,5 AMP. INST. !USE F-01 -I, 5 AMP. SLO BLO. +33 V +ltI/ SOURCE SOURC&: Part :/: A-DC-21 A-FW-B CEC-1000/75 CETM-1000/55 D-S 1-1 D-GM-3 F-AGX-2.5 F-SB-1 J-3-ST-8 J-3-ST-7 KN-007
33、 KN-006F KN-006R KN-005 M-SS-11 N-344C-l N-D-FM-25 QP-8 RCV-lOK-PH RWS-15-2X2 RW5-60 SR-2-50 SRW-125-1 SS-22 SS-43-3 S-PB-22X7 TR-13-3 V-PL-1819 V-PL-1847 Z-ANT-FM-2 Z-FM-15 Z-PC-MX-14 Z-PC-NS-3 Z-PC-Pl0 Z-PC-PS-7 Z-PC-IF-6 Z-PC-TD-8 344-C PARTS PRICE LIST Description Dial Cord Flywheel Assembly Ele
34、ctrolytic Capacitor Electrolytic Capacitor Diode Diode Fuse Fuse Phone Jack Phone Jack Knob Knob Knob Knob Meter Front Panel Dial Glass Power Transistor Potentiometer Stand-up Resistor Power Resistor Rectifier Switch Switch Switch Push Button Switch Power Transformer Bulb (Stereo) Bulb (Stereo) Dipo
35、le Antenna Front End Multiplex Board Squelch-Noise Pre a mp Boa rd Power Supply Board IF Strip Driver-Tone Board 16 Customer List $ 1. 75 4.80 4.32 3.43 .40 .32 .24 . 72 1.05 . 98 1.05 1.05 1.05 1.54 5.95 14.95 4.56 6.00 1.00 1.47 .32 .80 6.12 .40 . 72 8.40 26.75 .40 .40 1. 75 26.84 25.12 9.36 17.90 12.70 26.05 40.00
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