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MARANTZ DESIGN AND SERVICE

Using superior design and selected high grade components, MARANTZ company has created the ultimate in stereo sound. Only original MARANTZ parts can insure that your MARANTZ product will continue to perform to the specifications for which it is famous. Parts for your MARANTZ equipment are generally available to our National Marantz Subsidiary or Agent. ORDERING PARTS: Parts can be ordered either by mail or by telex. In both cases, correct part number has to be specified. If you order by mail, fulfil MARANTZ order forms. The following information must be supplied to eliminate delays in processing your order: 1. Complete address 2. Complete part numbers and quantities required 3. Description of parts 4. Model number for which part is required 5. Way of shipment 6. Signature: any order form or telex must be signed otherwise such part order will be considered as nuli and void.
PARTS OROERING Parts may be ordered at the following addresses: AUSTRIA HCRNYPHON Vertriebsgesellschaft Wienerbergstrasse 1 A 1101 Wien Austria Telex: 132.332 AUSTRALIA MARANTZ AUSTRALIA PTY., Ltd. 19 Chard Road Brookvale. NSW 2100 Australia Telex: 24121 BELGIUM SVD DIVISION MARANTZ Industrialaan 1 1720 Groot-Bijgaarden Belgium Telex: 24466 CHILE MARANTZ DIVISION OF PHILIPS AV. Santa Maria, 0760 Casllla 2687 Santiago Telex: 240.239 DENMARK MARANTZ DIVISION OF PHILIPS SERVICE A/S Prags Boulevard 80 Postbox 1919 DK-2300 Kebenhavn S Denmark Telex: 31201 FINLAND MARANTZ DIVlSION OF OY PHILIPS Ab Kaivokatu 8 00100 Helsinki Finland Telex: 124811 FRANCE MARANTZ FRANCE 4 Rue Bernard Palissy 92600 Asnières France Telex: 611651 GERMANY MARANTZ GERMANY GmbH Max-Planck-Strasse 22 6072 Dreieich 1 Germany Telex: 529821 THE NETHERLANDS Elpro b.v. De Limiet 3 4131 NR Vianen The Netherlands Telex: 47679 NORWAY MARANTZ DIVISION OF PHILIPS A/S Sandstuveien 40 Oslo 6 Norway Telex: 72640

TECHNICAL ASSISTANCE Should you require any other technical support, do not hesitate to contact the Technical Department of P.M.A. MARANTZ INTERNATIONAL Quality & Service Dept. 80, Rue des Deux Gares, B-1070 Brussels Belgium Phone: 02/525.70.22 or 525.70.23 Telefax: 02/525.6160 Telex: 23550 OR 61511 (PHEMB) routing: BELDMZT

GREAT BRITAIN MARANTZ AUDIO U.K. Ltd Unit 15/16 Saxon Way Industriai Estate Moor Lane Harmondsworth UB7 OLW Great Britain Telex: 935196 GREECE SHERTON ELECTRONICS S.A. P.O.Box 21025 Hippooratus Street 188 Athens 11471 Greece Telex: 216.795 JAPAN MARANTZ JAPAN, Inc. 35-1,7-chome, Sagamiono Sagamihara-shi,"Kanagawa Japan KUWAIT AL ALAMIAH ELECTRONICS Ussama Building Fahd al Saleem Street P.O.Box 23781 Safat-Kuwait Telex: 22694 ITALY MARANTZ ITALIANA S.P.A. Via Chiese, 74 20126 Milano Italy

SAUDI ARABIA AL ALAMIAH ELECTRONICS P.O.Box 5954 University Street Riyadh 11432 Saudi Arabia Telex: 201530 SOUTH AFRICA MARANTZ DIVISION OF PHILIPS S.A. Rainer House Ove Street, 10 Doornfontein Johannesburg Telex: 483.456 SPAIN PHONO S.A. Ignacio Iglesias 10 Badalona (Barcelona) Spain Telex: 59355 SWEDEN MARANTZ DIVISION OF PHILIPS Försäljning AB Tegeluddsvägen 1 S-115 84 Stockholm Sweden Telex: 14060

SWITZERLAND DYNAVOX ELECTRONICS Route de Villars 105 1701 Fribourg Switzerland Telex: 942377 TURKEY DOGRUOL Ltd. I.M.C. 6 Blok N°6310 Unkapani Istanbul Turkey Telex: 22085 MALTA CACHIA & GALEA Republic Street, 68D Valletta Telex: 1682 U.S.A. MARANTZ COMPANY, Inc. National Service Department P.O. Box 577 Chatsworth, CA 91311 U.S.A.

All of the above locations are fully equipped to take care of your total service needs. Because various countries have differing configuration requirements, it is necessary that you contact the service facility in your particular country, in the event that there is no service location listed for your country, please, contact the nearest facility for the necessary assistance. In case of difficulties, do not hesitate to contact the Technical Department at abovementioned address.

TABLE OF CONTENTS SECTION INTRODUCTION 1. P.W. BOARDS 2. TEST EQUIPMENT REQUIRED FOR SERVICING 3. VOLTAGE CONVERSION 4. ADJUSTMENT PROCEDURE 5. BLOCK DIAGRAM 6. SCHEMATIC DIAGRAM AND COMPONENT LOCATIONS
6.1 6.2 6.3 6.4 6.5 6.6 6.7 6.8 6.9 6.10 6.11 6.12 6.13 6.14 6.15 6.16 6.17 6.18 Tone/Tape 1, 2/VCR/Muting Assembly (PTOO) Schematic Diagram and Component Locations Speaker Muting Pelay Assembly (PR00) Schematic Diagram and Component Locations Tone (L) Assembly (PE01) Schematic Diagram and Component Locations Tone (R) Assembly (PE02) Schematic Diagram and Component Locations Phone/Speaker Selector Assembly (PR50) Schematic Diagram and Component Locations Power Amp.(L) Assembly (P600) Schematic Diagram and Component Locations Power Amp.(R) Assembly (P700) Schematic Diagram and Component Locations Soft Start Assembly (PN50) Schembly Diagram and Component Locations Tape Play/Rec/VCR Assembly (PW00) Schematic Diagram and Component Locations Comparator/Protect/Supply Assembly (PN00) Schematic Diagram and Component Locations Main Volume Assembly (PQ00) Schematic Diagram and Component Locations Phono Amp/Input Selector Assembly (P400) Schematic Diagram and Component Locations Function Selector Assembly (PV00) Schematic Diagram and Component Locations Function LED Assembly (PY00) Schematic Diagram and Component Locations CD Direct/Balance etc. Assembly (PK00) Schematic Diagram and Component Locations Power Transistor Assembly (PL00) Schematic Diagram and Component Locations Flat Amp/Supply Assembly (PG00) Schematic Diagram and Component Locations Tape/VCR/Muting Indicator Assembly (PZ00) Schematic Diagram and Component Locations

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5 5 6 6 6 7 7 9 9 10 10 11 12 13 13 14 14 15

7. EXPLODED VIEW AND PARTS LIST 8. ELECTRICAL PARTS LIST 9. TECHNICAL SPECIFICATIONS 10. SCHEMATIC DIAGRAM

16 21 29 30

How to use this service manual
· The "Common parts" which Marantz Japan, Inc. has established are eliminated from this service manual. · These "Common parts" are applied to all models in the service manuals arranged and issued by MJI. · To indicate clearly the common parts in the schematic diagram, a line is drawn above or under the Ref. Desig. No. of applicable parts. · "Common parts" can be supplied from the Marantz service center as ever. In case of ordering, please establish the parts number of 10 figures following the procedure mentioned in this service manual "How to establish the parts number for common parts". (NOTE) When you order parts to the Marantz parts center, please take notice of the following points. 1) 2) Please correctly write the parts number of 10 figures following the rule. Since ordering parts by the Ref. Desig. No. or ratings indicated in the schematic diagram does not satisfy the above conditions, the Marantz parts supply system does not work properly.

As this case is apt to cause a trouble, please pay attention to it.

MODEL PM-94 STEREO AMPLIFIER

INTRODUCTION
This service manual was prepared for use by Authorized Warranty Stations and contains service information for the Marantz Model PM-94 Stereo Amplifier. Servicing information and voltage data included in this manual are intended for use by knowledgeable and experienced personnel only. All instructions should be read carefully. No attempt should be made to proceed without a good understanding of circuitry operation. The parts list furnishes complete ordering information. Most replacement parts should be ordered from the Marantz Company. However, a simple description is included for parts which can be obtained locally.

1. P.W. BOARDS
As can be seen from the circuit diagram the chassis of Model PM-94 consists of the following units. Each unit mounted on a printed circuit board is discribed within the square enclosed by a bold dotted line on the circuit diagram.
1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. Tone (L) ......................mounted on P.W. Board PE01 Tone (R)......................mounted on P.W. Board PE02 Flat Amp/Supply ........mounted on P.W. Board PG00 CD Direct/ Balance etc ...............mounted on P.W. Board PK00 Power Transistor..........mounted on P.W. Board PL00 Comparator/Protec/ Supply..........................mounted on P.W. Board PN00 Soft Start Ass'y ...........mounted on P.W. Board PN50 Main Volume................mounted on P.W. Board PQ00 Speaker Muting Relay ............................mounted on P.W. Board PR00 Phono/Speaker Selector........................mounted on P.W. Board PR50 Tone/Tape 1 . 2 / VCR/Muting ...............mounted on P.W. Board PT00 Function Selector ...... mounted on P.W. Board PV00 Tape Play/ Rce/VCR.................... mounted on P.W. Board PW00 Function LED . . . . . . mounted on P.W. Board PY00 Tape/VCR/Muting Indicator ......................mounted on P.W. Board PZ00 Phono Amp/ Input Selector ........... mounted on P.W. Board P400 Power Amp (L) ...........mounted on P.W. Board P600 Power Amp (R) ........... mounted on P.W. Board P700

2. TEST EQUIPMENT REQUIRED FOR SERVICING
This table lists the test equipment required for servicing the Model PM-94 Stereo Amplifier.
Item

Use Distortion measurements Sinewave and squarewave signal source Voltage measurements (AC) Waveform analysis and trouble shooting and ASO alignment Trouble shooting Voltage measurements (DC) Monitors primary power to amplifier Monitors potential of primary power to amplifier Adjust level of primary power to amplifier Shorts amplifier input to eliminate noise pickup

Distortion Analyzer Audio Oscillator AC VTVM Oscilloscope Circuit Tester DCVTVM AC Wattmeter Line Voltmeter Variable Autotransformer (0 ~ 140V AC, 10A) Shorting Plug

3. VOLTAGE CONVERSION
EUROPEAN MODEL ONLY CAUTION DISCONNECT POWER SUPPLY CORD FROM AC OUTLET BEFORE CONVERTING VOLTAGE.

To convert the unit to a different power source voltage, change the position as illustrated in the drawing below.

Voltage Conversion Chart

Note on safety: Symbol

ñ

Fire or electrical shock hazard. Only original parts

should be used to replace any part marked with symbol

ñ.

Any

other component substitution (other than original type), may increase risk of fire or electrical shock hazard.

4. ADJUSTMENT PROCEDURE
1. 1) Adjustment of output offset voltage Remove the MAIN-IN and PRE-OUT plugs, and connect a digital voltmeter set to the DC range to the speaker terminals with no signal and no load on the unit. Adjust R622 for L-ch and R722 for R-ch until the indication on the digital voltmeter is ±10 mV. Idling adjustment With no signal or load on the unit, short TP-1 and TP-3 on the P.W. Board (PN00). Connect a digital voltmeter set to the DC range between J607 and J707 and adjust J643 and J743 for 36 mV. Remove the short between TP-1 and TP-3, and R642 and R742 so that the voltage between J607 and J707 is 180 mV. 7) 3. 1) Adjustment of quarter "A" Connect a DC voltmeter between the emitter and base of QL07 for L-ch. (The meter range is greater than 100 V, with the polarity of the emitter (+) and base Connect the oscilloscope between TP-1 and TP-2 on the P.W. Board, and monitor the waveforms at TP-2 with TP-1 as the reference. Connect an 8 ohm load to each of the speaker termi nals, and input a 1 kHz to the L channel MAIN-IN. Adjust the input level so that the load on L-ch gives output of 17 V. Rotate RN40 (RN41) on the P.W. Board (PN00) and monitor the waveforms on the oscilloscope. Lower the input signal and confirm that the voltage at the speaker terminal is 16 V -- 16,5 V and the voltage at the emitter of QL07 is 29 V at the point where the pulse disappears. 8) Next, connect the DC voltmeter between the emitter and base of QL08 for R-ch. (The meter range is greater than 100 V, with the polarity of the emitter (-) and base (+).) 9) Input a 1 kHz to the R channel MAIN-IN. Adjust the input level so that the load on R-ch gives output of 17 V. 10) Adjust items 4 to 7 in the same manner as L-ch. The adjustment locations are those shown in parenthesis. 6) Adjust RN40 (RN41) again to make the pulse width 0,1 ms. Confirm that the voltage at the emitter of Q107 is 63 V.

2)

2. 1) 2)

3)

2)

3)

4)

5)

Adjust RN42 (RN43) so that the pulse width is the same.