Sony MDSJE320 Service Manual - Page 3

SAFETY CHECK-OUT After correcting the original service problem, perform the following safety checks before releasing the set to the customer: Check the antenna terminals, metal trim, "metallized" knobs, screws, and all other exposed metal parts for AC leakage. Check leakage as described below. LEAKAGE The AC leakage from any exposed metal part to earth Ground and from all exposed metal parts to any exposed metal part having a return to chassis, must not exceed 0.5 mA (500 microampers). Leakage current can be measured by any one of three methods. 1. A commercial leakage tester, such as the Simpson 229 or RCA WT-540A. Follow the manufacturers' instructions to use these instruments. 2. A battery-operated AC milliammeter. The Data Precision 245 digital multimeter is suitable for this job. 3. Measuring the voltage drop across a resistor by means of a VOM or battery-operated AC voltmeter. The "limit" indication is 0.75 V, so analog meters must have an accurate low-voltage scale. The Simpson 250 and Sanwa SH-63Trd are examples of a passive VOM that is suitable. Nearly all battery operated digital multimeters that have a 2V AC range are suitable. (See Fig. A) To Exposed Metal Parts on Set 0.15 µF 1.5 kΩ AC Voltmeter (0.75 V) Earth Ground Fig. A. Using an AC voltmeter to check AC leakage. MODEL IDENTIFICATION - BACK PANEL - TABLE OF CONTENTS 1. SERVICING NOTE 5 2. GENERAL 8 3. DISASSEMBLY 3-1. Case and Front Panel Assembly 9 3-2. Bracket (T), (L) and (R 9 3-3. BD Board 10 3-4. SUB Chassis 10 3-5. Shutter Assembly 11 3-6. Over Write Head 11 3-7. Slider Complete Assembly 12 4. TEST MODE 13 5. ELECTRICAL ADJUSTMENTS 16 6. DIAGRAMS 6-1. Brock Diagrams • BD Section 21 • Main Section 23 6-2. Circuit Boards Location 25 6-3. Printed Wiring Board - BD Section 27 6-4. Schematic Diagram - BD Section (1/2 29 6-5. Schematic Diagram - BD Section (2/2 31 6-6. Printed Wiring Board - Main Section 33 6-7. Schematic Diagram - Main Section (1/3 35 6-8. Schematic Diagram - Main Section (2/3 37 6-9. Schematic Diagram - Main Section (3/3 39 6-10. Printed Wiring Board - Display Section 41 6-11. Schematic Diagram - Display Section 43 6-12. Printed Wiring Board - Switch Section 45 6-13. Schematic Diagram - Switch Section 47 6-14. IC Brock Diagrams - BD Section 49 6-15. IC Pin Functions 54 7. EXPLODED VIEWS 7-1. Main Section 63 7-2. Front Panel Section 64 7-3. Mechanism Deck Section (1) (MDM-3GC 65 7-4. Mechanism Deck Section (2) (MDM-3GC 66 8. ELECTRICAL PARTS LIST 67 Parts No. Parts No. 4-990-651-1 4-990-651-4 4-990-651-5 Model US model Canadian model AEP model - 3 -