McIntosh MR78 Tuner Service Information Early Production.pdf

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1、nfctnlosh t 6 fU 1 IT 18 S-CtfCf IVITY #tTf* smto *v*o KOS#M TUNER FROM SERIAL NO. AD1001 TO A D 5 1 6 4 McIntosh laboratory inc. 2 chambers street binghamton, new york MR 78 MR 78 ELECTRICAL SPECIFICATIONS SENSITIVITY 2 pV for better than 35dB quieting. 2.5pV IHF usable sensitivity Max., 1.9pV typi

2、cal. SELECTIVITY IMF No rma1 Na r row S upe r-Na r row ADJECENT CHANNEL 7dB 2 2dB 55dB ALTERNATE CHANNEL 55dB 90dB 90dB SIGNAL TO NOISE RATIO Better than 75dB below 100% modulation. HARMON IC DISTORTION Less than 0.2% mono or stereo at 100% modulation 20Hz to 18kHz. Typically less than 0.05% at 1kHz

3、. FREQUENCY RESPONSE + 1dB 20Hz to 18kHz with standard 75pS de-emphasis. CAPTURE RATIO Better than 2.5dB IHF. SPURIOUS REJECTION Greater than lOOdB IHF. IMAGE REJECTION Greater than lOOdB 88 to 108MHz IHF. STEREO SEPARATION Better than 40dB at 1 kHz. SCA FILTER 50dB down from 67kHz to 74kHz; 275dB p

4、er octave slope. POWER REQUIREMENTS 120VAC, 50 - 60Hz, 35W. (NORMAL SELECTIVITY UNLESS OTHERWISE STAT ED I SELECTIVITY |f SELECTIVITY 10.7 MHz |f SELECTIVITY 10.7 MHz ,F IF BRIDGE TO SWITCH - AMP J | SWITCH i-*- NORMAL AMP SWITCH NORMAL AMP - POWER - DISCRIMINA-BASE BAND (PARTIAL) _ (PARTIAL) FILTER

5、 (PARTIAL) FILTER AMP/ TOR AMPLIFIER O SIGNAL STRENGTH OUTPUT 78 BLOCK DIAGRAM SUPPLY MR 78 SCHEMATIC NOTES 1. Unless otherwise specified: Resistance values are in ohms, 1/4 watt, and 10% tolerance; Capacitance values smaller then 1 are in microfarads (pF); capacitance values greater than 1 are in p

6、icofarads (pF); inductors are in microhenries (pH). 2. Printed circuit board components are outlined on the schematics by dotted lines. The circled numbers around the dotted lines correspond to the numbers on the PC Board layouts. 3. The heavy lines on the schematics denote the primary signal path.

7、4. The terminal numbering of rotary switches is for reference only. 5. All voltages indicated on the schematics are measured under the following conditions : a. Use of an 11 megohm input impedance VTVM. b. All voltages +10% with respect to chassis ground. c. No signal at input or antenna terminals.

8、d. AC input at 120 volts, 50/60 Hz. e. Front panel controls at: Tuning indicator 100MHz (no signal ) Muting Out Vo 1ume Fully CW Mode Auto Selectivity No rma1 Meter Sig. Strength Filter Out Panel Lights Bright 6. 1 n units with Serial Nos, be 1ow AD 1501 R612 is 3.3k and R613 is 150k 7. 1 n units wi

9、th Serial Nos, below AD 1508 C602 and C603 are .01pF. 8. 1 n units with Serial Nos below AD4878 C331 and C334 are .0033. 9. 1 n units with Serial Nos below AD5014 C26 is 5pF, C27 is 9pF and C25 is 0.5-3pF. In units with Serial Nos below AD5014 R15 and C34 are not used. In the power supply section D5

10、08, R512, C508 and C509 are not used. 10. MR 78 TUNING CONDENSER DRUM (TOP VIEW) -)b TO PIN 9 OUTPUT AMP PC BOARD - - 12V SELECTIVITY TO POWER SUPPLY LAMPS PC BOARD / SECT 2 FRONT SEL JUNCTION PC BOARD 044-565 i 1 B 2 K 8.2K 15V 24V 24V 124V 7V 24V 7V LI 15V 24V 24 V O-“ |24V Tr dm TWHT/TVHT TO DETE

11、CTOR PC BOARD TUNER SECTION 154-699 H 10 u f/35V H 308 + 0304) FM DETECTOR PRINTED CIRCUIT BOARD 044-351 NOTE DETECTOR SECTION MR 78 154-620 MR 78 MR 78 OUTPUT AMPLIFIER PC BOARD 044-349 ORN /-N f 24 V -( I LEFT AUDIO INPUT FROM PIN 14 0 MPX PC BOARD R 409 A A A _| tov/t V V V 2.2 K C405 _1/_ t 15 p

12、F RIGHT AUDIO INPUT FROM PIN 13 MPX PC BOARD 5 ro . * - oj o 24V BLU/WHT SIGNAL STRENGTH/ MULTI PATH R422 TO PIN MPX PC BOARD LEFT FIXED OUTPUT r Xrs LEFT Y VARIABLE OUTPUT TO PIN MPX PC BOARD RIGHT FIXED OUTPUT RIGHT VARIABLE OUTPUT OUTPUT AMP SECTION MR78 154- 546 OUTPUT AMP PC BOARD 044-349 POWER

13、 SUPPLY PRINTED CIRCUIT BOARD 044-453 POWER SUPPLY PRINTED CIRCUIT BOARD 044-453 I- I POINTER BRN LIGHT 1666 1666 1666 I TO MUTING.FILTER AND DIAL SCALE INTENSITY SELECTIVITY LAMPS POWER SUPPLY SECTION IIIIMI / # p f /11 * * p f ft! i I * |i * p: i i - , 1*#S * ? / 7 / 7 T in * OJ rO j i 3 o O o O O

14、 O o 9 O i=o o 00 o (D 1 MR 78 ALIGNMENT INSTRUCTIONS 0 X c 3 1- 0 1L =5 O 3 X 0 0 00 CT c % DO 0 Ll. 0 3 1_ u cr 0 i_ 0 s_ 0 CL i_ O O LA . 1 0 . r. 0 i 4-J X 00 LA Csj X 0 X 0 CO 0 CO ID 0 i_ . X CA 4-J - CO , 0 CO c 1- 0 2 C 4-J - 0 U CM 0 0 c (D 1_ 0 0 E L 0 - O E 4-J N- 1- X 1_ v 0 CD X 0 X X 0

15、 . X CD 0 L. 0 O- 0 X CL 0 4-0 1 1 C CL - - c CL X 0 . 1 0 X N_X J_J 0 !_ 0 x0 0 c 2 _ 0 0 O 0 i_ . 0 00 4-* 4-J CLX 0 2 CD 0 0 X i_ X 0 CD O VO 0O 2 c 0 _ O LL c 0 O! CO CO 0 4-J X OI 0 4- ID C 0 ID C LA *E LS LS X O 0 CL 0 EE * Ll. Z O 0 O + 1 Q r CD N c CL X 4-J x 0 X 0 EE CD O Q. O X * j- X C 3

16、X C CO X C X 4-1 X 0 r. 4-j r-N. 0 cr E 0 r- ID ID O CLO 0 U X CD u 1 3 0 c c 000 u O ID i_ 0 i- 0 - Li- h- XI- U - O X 0 0 CO - CD -l-J 0 CM 1-A J- LA X r. CO ID x c c 0 0 0 c CL Ex c u * 0 0 0 - X E i_ 0 X O Z c X Ll. 3 X 0 C CD CO c c 0 CO 0 s H 0 X ID r- - X i X 0 4-J X L. U x CL 0 0 O LU X ID *

17、x 1- 0 X 1- X 4-J X CD U 0 X X CL 0 2 C 3 X C 4- c E 3- ID 0 ID CD 3 0 0 0 C LL - 0 X 4-J C 0 X X 0 - CD L- X i/l 0 c u X 0 CM X 0 1- 4-J 0 CD 0 X _1 LD 2 O X c X LA X CDX 4-J 0 c: 0 X fA c 0 0 C 3 0 0 X ID 1 X 0 X 1- CL C 4-J 0 fA s u 0 i/l CD 0 * X X CM 0 L. 0 c =J !_ E u O C Pn. LL. 0 X 0 . i_ 1-

18、 0 c 1 0 LJ CD - 0 0 O 0 L- 0 r. ID 0 C l X 0 4_ CL 3 x X 0 E 2 N O 4-J 1- C O U X X 0 x 4-J 1- U 3 - X u c 2: U 4-1 0 CL 0 0X0 c LL CD 0 4-J 0 x c c 2 0 CO X 0) 4-J 0 0 ID 0 0 0 O E 0 0 4-J X Ex 0 - v_ * 0 t F 4-J x x cl 1- O 0 X - X CL - c J- 0 3 c l 4-J - 0 E L- 0 0 0* X 0 ID 1- O 0 4-J E Cl 0 X

19、0 E XCO -*-1 5 0 ID c 0 x CL u CO CD ID ID O CD 0 - 21 0 c 3 l/i 0 0 0 0 1 1- c u c X 1 X U 4-1 0 CA 21 CL 1- 0 0 0 0 0 0OO Ll. 0 3 4-* C 0 CD c CA X X) rA c O C 0 4-J 2 ID 1_ 0 L- 0 E Ll. 4-J O 0 i_ E CL ID X 0 X CO 0 c - 3 X c/1 E 0 -* p 0 LL X CD 4 ID e 0 - x 4-J 4-J , i-i- i_ X - X (D 4J L 4-j C

20、O = U 0 O O 0 1- 0 c 0 (D 0 0 0 E - 0 0 E X 4-J 4-J . L- 0 CD CD C L. 0 U U 1-CL 0 0 x3 C c c 0 c X CD 0 0 X X ID 0 . X X CD X c X X 3 Z 2 CD X 1_ . - 0 0 3 0 0 0 O 0 3 X 0 -0 u x CTX C . CO CO b CL CD X . (DUO O X 1-11- ID 0 X X 0 E 0 O 4-J X E z 1 CNJ x 0 ID 4- 2 X c 0 0 =5 C L. COX X M 0 X 1-0 0

21、1- 4-j 0 U CD X 0 E 0 0 J- 0 C E c 1- CLX C 3 0 q. c 00 - 0 X E X C CO U 3 Q_ c E 0 X c 0 3 O CT Q. C 1- u 0 cr id cr -v 0 0 0 “ 0 0 4-J 3 0 X 4-J c l- X 4J4- L ID X CD CL 0 CT 0 0 3 0 C 0 ID 0 X O x 0 ID 1- 3 - id c E X ID c 0 0 cr 0 4-j 000 ID O 0 4-J L- 1- 0 0X0 X c 0 0 X ID 4-J 3 4-J c c 0 4-J 4

22、-J ID U X CsJ 0 U 4-J M- 0 U CD 0 X E X ID 1-3 3 X 0 X X 0 - cr 0 U 0OO 4_J X CD C 0 4-J 1 1 0 0 l- u -Q_ 4 X X 4- X 0 c . 4_ l/l u 0 1- h- O Ll. ID X 0 CL O O (D c 0 CD X (J 0 0 X 4-j . X _ 0 1 X O E u 0 0 0 X CD 0 X l- O 0 x u X CL X . 0 X x 0 0 X 0 O x 0 0 C co 0 X X 0 3 c X 0 U 0 * 2 c 0 X E 0 0

23、 X oa CL X 0 ID 0 i_ 0 , X C CL U 0 X 3 O 0 0 Cl 2 O X CLX X (D CLX 0 ID co -a X ID c 0 X X 3 1_ 0 0 x i_ 0 0 0 c x c 0 cnx . c 0 X 5- 0 0 0 0 Cl 0 x ID u u CDX X r i_ c X 0 O 0 CL 0 0 0 1 4-j - ID Cl 1 0 1 X c X , X C 0 2 c 0 0 X 0 CL 1- O 2 CD CL 0 Cl 0 1- O X 0 CO 0 X X c E 1_ X 0 0 0 0 c i_ c CL

24、 L. 0 41 CD CD 0 0 0 ID C ID CL 0 1_ ID C O CNJ X 0 X ID 0 c 1_ CL 4-1 CL CL CL X 0 0 0 e 1 ID 0 ID CD 0 0 0 X X 3 0 O xl 1_ 40 E CL u D-C O U 4-J c o N OX Q_ D X (J CM X 3 id O (D I fD C- r-_= Q. 0 UT3 O i/l O O 3 C a * o CD E X X CD i/l O C L. _D 0=5 0 VO 4-J 4-J C (DO Ll i/l 0 CM d) Li_ c CL I _G

25、 CD X CD -.“0 O (0 L i/i C O 0.(1)- 0 L- X X = CD CD 4-J _C 14- - 4-J 1/) 4-J O U 0 LA C 0 4-1 LQ CD L I/l 0 cm U O O C 3 01- U Q. CD in X CD -O cnr- ll X L- X CD CD O CD C 21 X E CD O - LL 1 I v LA 1/1 4-J r- i_ CD O +1 CD E * -X N J- X CD w OI E CD E CD CD U l X- LD l/l 1_ 4-J O 1 E CD O CD CD O i

26、/i X) X 1/1 4Ji 4-J in C CD 0 XX CD CD 4-J OX L_ OX 4-J CD O C C X in X LJ in 4-J CD U i/i =5 o CD =5 _ (DXQ-EEUi- c/i c CD O O U X X D - 1- D QC CD 4-J O o t X -X O vO . o (s, 0 O 4-J CM CL CD + 1 0 j- 0 2: 5 N e N cd CD 1 N X (D X OO X 2: c uco 2: (o 0 C c c =3 CD N X c X c 1 c 2! 1_ 0 CO 0 0 0 0

27、O 0 r. CL C X 0 3 * 1_ U x 1 N E 0 1_ X 0 C 0 OO I 0 0 0 +J 0 X co 2; CO It O CD m cd c tD O j_ (Dec wOO 0 E c +- C 0 CD- U C w 0 x cue 3 J-J -O C c 00 . 1- 4- 0 c CD ID 3 0 E u u 0 C x x 0 0 c O 0 CO O X 0 or: x 3 ID Q_ X 0 x Q C ID 3 4-J o C 1_ 0 N CD E X 4-1 X in x IM. D 0 X in |X X X u E U 0 0 D

28、 0 0 E i 4-J i_ 0 C 4-J 0 ID 3 CL ECl 0 4-J cc c L- 3 O 0 o 4 4-J X ex 0 s- x O C 0 c fX 3 0 O 1 +J X u - W X E N 0 0 =3 X E X N CL ex X 4- LAX 4* Cl P-, O EX 3 3 E i E +- u 0 LJ X 0 4-J C 0 4-1 3 E 0 0 X ID CX i_ 0 o 0 O ex 4J U 1 CM 4* 0 X O Q_X C ex E 0 0 -J 0 i_ 4-* CL CM j_i 4_ o ID 0 0 ex 3 a_

29、i i-*-1 0 X 0 u n- O 0 X in u Q_ C 0 N 0 X O CL 0 CL CO o -M ON CD 0 O E CD s_ O 0 C C O 0 M- n 0 X) XI O 0 U C O O St moc x -u CD 0 0 O C L. L. C - 0 0 - c id cl ( 0 0 E -m X in O 0 C o 0 M 0 0 (D E -M = O E -Q 0 X X X cl u 0 xr 0 0 X u u c 0 (DC1 , o o 0 i_ 4-J 0 3 m I-3 O 0 C o 4- o x o 0 i_ s_ N

30、 N X 0 xxx _x x un MtDM 0 D LA +|X X x N -M X l 4- 0 X 3 0 W P X O *- o o E c O C Cl 0c O $_ O 0 0 o +- x 4- 0 c 0 C oo -I 00 O O 0 0 0 i- 1 3 . 0 i- X M 0 O C co u E O ID CD 0 0 C x 3 C C X i- c o X 0 x o 0 a 0Exi_0oc u x O L-I S- 4- Cl -mo 014-1 4J O C 0 CL0O 0 0 L. tci n +j J iD E idEO O C - x c

31、0 0 CM CO uo h- 6 5 CD R 78 REPLACEMENT PARTS All parts able from not listed are common radio parts jobbers. i terns obtain- Replacement parts may be by PART NUMBER from: obta i ned when ordered McIntosh Laboratory, Inc. Customer Service Department 2 Chambers Street Binghamton, New York 13903 (telep

32、hone 607-723-3512) CAPACIT0RS C29,30 S i 1ver Mica 2 70p F 063-010 C204 Elect . 1 OpF 35 V 066-173 C304 Tant.Elect. 1 Op F 20 V 066-239 C 306 Tant.Elect. 2 2 pF 25V 066-240 C 308 Tan t.E1ec t. 6.8nF 35V 066-146 c 309 Polystyrene 2 700p F 064-093 C 31 0 Tant.E1ect. 10pF 20V 066-239 C 31 1 Polystyrene

33、 1500pF 064-092 C31 4 Tant.E1ec t . 6.8pF 35V 066-146 C 31 6 Tant.Elec t. 6.8 |_i F 35 V 066-146 C 3 2 3 Tant.Elect. 1 uF 50V 066-242 C 32 5 Tan t.E1ec t . 2 2 pF 25V 066-240 C 3 2 6,32 7 Po1 yetyrene 4700pF 064-091 C 32 8 Ta n t.E1ec t. 6.8pF 35 V 066-146 C 3 31 Polystyrene 0033pF 064-090 C 334 Pol

34、ystyrene .0033pF 064-090 C401 ,402 Polystyrene 2700pF 064-093 C403 Polystyrene 033pF 064-089 0406,407 E1ec t.Cap. 2 2 pF 35 V 066-179 C 41 1 E!ect . Cap. 1 OpF 50 V 066-221 C 41 2 Po1ys t yrene 2 700p F 064-093 041 3 Tant.Elect. IpF 50V 066-242 0414 El ect . 1 OpF 50V 066-221 0503 Elect. 2000pF 50V

35、066-154 0504 Elect . 5/300/150/1000mF066-155 200/50/50/30V 0506 Elect. 1 50pF 63V 066-205 C507 E 1 ec t . 47hF 1 6V 066-215 D 1 ODES D1 Pin diode 070-055 D2 Si. signa diode 070-047 D3 Pin diode 070-055 D101,102 Si. signa diode 070-047 D1 03 Si. signa diode 070-047 D104,105 Ge. signa diode 070-003 D2

36、01,202 D203 D204 D205 D206,207 D208.209 D 2 1 0 D21 1 ,212 D21 3,214 D215,216 D301,302 D303.304 D305,306 D308,309 D310.311 D401 D502,503 D504 D505 D506 D601,602 0603,604 LI L2 L3 L4 L5 L6 n L 30 1 L302,303 L304 L501 Q1 Q2 03 Q1 01,102 Q201,202 Q301 Q302 Q303 Q304.305 S i signal d ode 070-047 Si sign

37、al d lode 070-047 Ge s i gna 1 d i ode 070-003 S i s i gna 1 d i ode 070-047 Ge s i gna 1 d i ode 070-003 Si s i gna 1 d i ode 070-047 Ge s i gna 1 d i ode 070-003 Si s i gna 1 d i ode 070-047 Ge s i gna 1 d i ode 070-003 Ge signal d i ode 070-003 Si s i gna 1 d i ode 070-047 Si s i gna 1 d i ode 07

38、0-047 Si s i gna 1 d i ode 070-047 Si s i gna 1 d i ode 070-047 Si signal d i ode 070-047 Si s i gna 1 d i ode 070-047 Si signal d i ode 070-031 Si s i gna 1 d i ode 070-031 Zener diode 24 V 070-065 Si . signal d i ode 070-031 Si . signal diode 070-081 Si . signal d i ode 070-081 CHOKES Antenna Co 1

39、 122-133 RF input Coi 1 122-132 RF output Coil 122-131 Mixer Coil 122-130 Osci1 1 a tor Co i 1 122-129 Choke 75 pH 122-013 Choke 1:7pH 122-032 Fi Iter Coi (19kHz) 122-094 Fi Iter Coi (SCA) 122-093 Choke 1MH 122-092 Choke 2.2 pH 122-001 TRANS ISTORS Si . N Channel J.F. Si . NPN t ransistor S i . NPN

40、t rans i stor M.O .S. F.E.T Si . Junction FET Si . NPN t rans i s tor S i . NPN t rans i stor Si . NPN t rans i stor 132-097 132-066 132-087 132-088 132-068 132-092 132-094 132-09? 132-094 Si. NPN t ransistor MR 78 0306 Si . N P N transistor 132-095 Q401 Si . PNP t rails i st or 132-096 Q402 Si . NP

41、N transistor 132-090 Q403 Si . PNP transistor 132-096 Q404 Si . NPN transistor 132-090 Q405 S i . NPN transistor 132-094 Q501 Si . NPN t ransistor 132-065 Q 5 0 2 Si . PNP transistor 132-032 0601 602 S i . NPN transistor 132-066 FUSES F501 Fus e .5A slo-blo 089-020 POTENTIOMETERS R2 1 2 M401 mid sca

42、le odv. 134-?60 R 2 2 6 M401 full scale adv. 134-260 R317 A uc ip 1 eve 1 134-258 R42 2 Vo 1 uire control 134-217 R42 3 Separation adv. 134-R60 R603 B i a s adv. 134-256 R61 0 M 301 adv. 134-256 RES 1STORS RIO wire 2 2 0 2 5. 1W 139-076 R 3 3 3 , 3 3 4 f i 1 m 33K 1 1W 144-015 R 338,339 film 33K 1 1

43、W 144-015 R50 3 w i r e 1551 107 5W 139-041 R508 wire 2 .02 10/ 5W 139-005 R509 w ire 1 .8 si 10/ 1W 139-077 R605,606 wire 220n 5 1W 1 39-076 R607 608 film 56 .251 1/ 1W 144-014 SWITCHES S2 Se1ectivity switch 146-156 S 301 Mode selector 146-160 S 3 0 2 Mut i ng switch 146-159 s4o l Stereo filter swi

44、tch 146-158 S402 Meter function switch 146-157 TRANSFORMERS T 1 Ba 1 un 043-226 T 2 FM n i x e r 162-062 T20 1 FM IF filter input 162-053 T202 FM IF filter output 162-052 T203 FM IF filter input 162-053 T204 FM IF filter output 162-052 T205 FM IF fit ter input 162-053 T206 FM IF filter output 162-05

45、2 T207 FM IF filter input 162-053 T208 FM IF filter output 162-052 T 301 RF transformer (!9kHz) 162-055 T 302 RF transformer (38kHz) INTEGRATED CIRCUITS 162-054 1 Cl Integrated circuit 133-006 1 Cl 01 , 1 02 1nteg rated circuit 133-002 IC30IA,13 Integrated circuit METERS 133-004 M301 Tuning mete r 124-020 M40I Signal strength meter RELAY 1 24-019 K301 Reed relay LAMPS 087-008 Function lamp 058-043 Stereo lamp 058-042 1847 (Meter lamp) 058-008 n1866 (Front panel) 058-014 Festoon lamp (Dial glass) FRONT PANEL & TRIM 058-0