Sony mds jb 940 service manual
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Extracted text from sony mds jb 940 service manual (Ocr-read)
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2 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 microamperes). 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) SAFETY CHECK-OUT To Exposed Metal Parts on Set 0.15 µF 1.5 kΩAC Voltmeter (0.75 V) Earth Ground Fig. A. Using an AC voltmeter to check AC leakage. TABLE OF CONTENTS MODEL IDENTIFICATION - BACK PANEL - Model AEP, UK models Canadian model US model Part No. 4-228-507-0s 4-228-507-1s 4-228-507-2s Par t No. SELF-DIAGNOSIS FUNCTION ········································4 1. SERVICE NOTE ·······························································6 2. GENERAL ········································································11 3. DISASSEMBLY ······························································14 4. TEST MODE ···································································17 5. ELECTRICAL ADJUSTMENTS ······························22 6. DIAGRAMS 6-1. Block Diagram MAIN Section································31 6-2. Block Diagram DISPLAY/POWER Section···········32 6-3. Note for Printed Wiring Boards and Schematic Diagrams····················································33 6-4. Circuit Board Location················································33 6-5. Waveforms···································································34 6-6. Printed Wiring Board BD Board·····························35 6-7. Schematic Diagram BD Board (1/2)·······················36 6-8. Schematic Diagram BD Board (2/2)·······················37 6-9. Printed Wiring Board HP Board/KEY Board··········38 6-10. Schematic Diagram HP Board/KEY Board············38 6-11. Schematic Diagram MAIN Board (1/3)··················39 6-12. Schematic Diagram MAIN Board (2/3)··················40 6-13. Schematic Diagram MAIN Board (3/3)··················41 6-14. Printed Wiring Board MAIN Board (Side A)··········42 6-15. Printed Wiring Board MAIN Board (Side B)··········43 6-16. Printed Wiring Board PANEL Section····················44 6-17. Schematic Diagram PANEL Section·······················45 6-18. Schematic Diagram AC Board································46 6-19. Printed Wiring Board AC Board······························47 6-20. IC Block Diagrams······················································48 6-21. IC Pin Function Description········································53 7. EXPLODED VIEWS ······················································60 8. ELECTRICAL PARTS LIST ·······································64
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3 SAFETY-RELATED COMPONENT WARNING!! COMPONENTS IDENTIFIED BY MARK 0 OR DOTTED LINE WITH MARK 0 ON THE SCHEMATIC DIAGRAMS AND IN THE PARTS LIST ARE CRITICAL TO SAFE OPERATION. REPLACE THESE COMPONENTS WITH SONY PARTS WHOSE PART NUMBERS APPEAR AS SHOWN IN THIS MANUAL OR IN SUPPLEMENTS PUBLISHED BY SONY.ATTENTION AU COMPOSANT AYANT RAPPORT À LA SÉCURITÉ! LES COMPOSANTS IDENTIFÉS PAR UNE MARQUE 0 SUR LES DIAGRAMMES SCHÉMATIQUES ET LA LISTE DES PIÈCES SONT CRITIQUES POUR LA SÉCURITÉ DE FONCTIONNEMENT. NE REMPLACER CES COMPOSANTS QUE PAR DES PIÈSES SONY DONT LES NUMÉROS SONT DONNÉS DANS CE MANUEL OU DANS LES SUPPÉMENTS PUBLIÉS PAR SONY. This appliance is classified as a CLASS 1 LASER product. The CLASS 1 LASER PRODUCT MARKING is located on the rear exterior. The following caution label is located inside the unit. Laser component in this product is capable of emitting radiation exceeding the limit for Class 1. CAUTION Use of controls or adjustments or performance of procedures other than those specified herein may result in hazardous radiation exposure. Notes on chip component replacement -Never reuse a disconnected chip component. -Notice that the minus side of a tantalum capacitor may be damaged by heat. Flexible Circuit Board Repairing -Keep the temperature of soldering iron around 270˚C during repairing. -Do not touch the soldering iron on the same conductor of the circuit board (within 3 times). -Be careful not to apply force on the conductor when soldering or unsoldering. ADVARSEL Eksplosjonsfare ved feilaktig skifte av batteri. Benytt samme batteritype eller en tilsvarende type anbefalt av apparatfabrikanten. Brukte batterier kasseres i henhold til fabrikantens instruksjoner. VARNING Explosionsfara vid felaktigt batteribyte. Använd samma batterityp eller en likvärdig typ som rekommenderas av apparattillverkaren. Kassera använt batteri enligt gällande föreskrifter. VAROITUS Paristo voi räjähtää, jos se on virheellisesti asennettu. Vaihda paristo ainoastaan laitevalmistajan suosittelemaan tyyppiin. Hävitä käytetty paristo valmistajan ohjeiden mukaisesti.ADVARSEL! Lithiumbatteri-Eksplosionsfare ved fejlagtig håndtering. Udskiftning må kun ske med batteri af samme fabrikat og type. Levér det brugte batteri tilbage til leverandøren. CAUTION Danger of explosion if battery is incorrectly replaced. Replace only with the same or equivalent type recommended by the manufacturer. Discard used batteries according to the manufacturers instructions. The laser diode in the optical pick-up block may suffer electrostatic break-down because of the potential difference generated by the charged electrostatic load, etc. on clothing and the human body. During repair, pay attention to electrostatic break-down and also use the procedure in the printed matter which is included in the repair parts. The flexible board is easily damaged and should be handled with care. NOTES ON LASER DIODE EMISSION CHECK The laser beam on this model is concentrated so as to be focused on the disc reflective surface by the objective lens in the optical pick- up block. Therefore, when checking the laser diode emission, observe from more than 30 cm away from the objective lens.NOTES ON HANDLING THE OPTICAL PICK-UP BLOCK OR BASE UNIT