Page 1
1 Safety Precautions 3
1.1. General Guidelines
3
1.2. Caution for
AC Cord (For GS only)
4
1.3. Before Use
5
1.4. Before Repair and Adjustment
5
1.5. Protection Circuitry
5
2 Prevention of Electro Static Discharge (ESD) to
Electrostatically Sensitive (ES) Devices
6
3 Warning
7
3.1. Service caution based on legal restrictions
7
4 Accessories
8
5 Operating Instructions Procedures
9
5.1. Main Operation Buttons
9
6 Assembling and Disassembling
10
6.1. Caution
10
6.2. Disassembly Procedures
10
6.3. Disassembly Flowchart
10
6.4. Main Parts Location Diagram
11
6.5. Before Disassembly
11
6.6. Disassembly of Front Cabinet
12
6.7. Disassembly of Speaker
12
6.8. Disassembly of Deck Mechanism
13
6.9. Disassembly of Main P.C.B.
13 6.10. Disassembly of Power P.C.B./ Battery P.C.B.
14
6.11. Disassembly Gear Knob
14
6.12. Disassembly for Pointer Guide
14
6.13. Disassembly and assembly for Cassette Compartment
15
6.14. Rectification for tape jam problem
15
7 Service Position
16
7.1. Checking Procedures
16
7.2. Checking and Repairing of Main, Battery, Mic and Power
P.C.B.
16
8 Adjustment Procedures
17
8.1. Tuner Section
17
8.2. Deck Section
19
8.3. Alignment Point
20
9 Wiring Diagram
21
10 Notes of Schematic Diagram
23
11 Schematic Diagrams
25
12 Printed Circuit Board Diagrams
27
13 Illustration of ICs, Transistors and Diodes
29
14 Exploded Views
30
14.1. Deck Mechanism Parts Location
31
14.2. Cabinet Parts Location
33
14.3. Packaging Materials and Accessories
35
15 Replacement Parts List
36
CONTENTS
Page Page
2
RX-M50M3GU / RX-M50M3GC / RX-M50M3GS / RX-M50M3GS1
Page 2
1 Safety Precautions
1.1. General Guidelines
1. Whenservicing observe the original lead dress. If a short circuit is found, replace all parts which have been overheated or
damaged by the short circuit.
2. After servicing, ensure that all the protective devices such as insulation barriers, insulation papers shields are properly installe d.
3. After servicing, check for leakage current to prevent from being expose d to shock hazards.
1.1.1. Leakage Current Cold Check
1. Unplug the AC cord and connect a jumper between the two prongs on the plug.
2. Using anohmmeter measure the resistance value, between the jumpered AC plug and each exposed metalliccabine t part on
the equipment such as screwheads, connectors, control shafts, etc.When the exposedmetallic part has a return path to the
chassis the reading should be between 1M-„¦and 5.2M-„¦.
When theexpose d metal does not have a return path to the chassis, the reading must be
.
1.1.2. Leakage Current Hot Check (See Fig. 1)
Fig. 1
1. Plug the AC cord directly into the AC outlet. Do not use an isolatio n transformer for this check.
2. Conne ct a 1.5k-„¦, 10 watts resistor, in parallel with a 0.15µF capacitors, between each expose d metallic part on the set and a
good earth ground such as a water pipe, as shown in Fig. 1.
3. Use an AC voltmeter, with 1000 ohms/volt or more sensitivity, to measure the potential across the resistor.
4. Check each expose d metallic part, and measure the voltage at each point.
5. Reverse the AC plug in the AC outlet and repeat each of the above measurements.
6. The potential at any point should not exceed 0.75 volts RMS. A leakage current tester (Simpson Model 229 or equivalent) may
be used to make the hot checks, leakage current must notexceed 1/2 milliamp. Should the measurement outside of the limits
specified, there is a possibility of a shock hazard, and equipment should be examine and reached before it is returned to the
customer.
3
RX-M50M3GU / RX-M50M3GC / RX-M50M3GS / RX-M50M3GS1
