Sony MDS-JE470 Service Manual - Page 5

SECTION 1 SERVICE NOTES MDS-JE470 SAFETY CHECK-OUT (US model only) 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 NOTES ON HANDLING THE OPTICAL PICK-UP BLOCK OR BASE UNIT 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 Never look into the laser diode emission from right above when checking it for adjustment. It is feared that you will lose your sight. Laser component in this product is capable of emitting radiation exceeding the limit for Class 1. This appliance is classified as a CLASS 1 LASER product. The CLASS 1 LASER PRODUCT MARKING is located on the rear exterior. This caution label is located inside the unit. 0.15µF 1.5kΩ AC voltmeter (0.75V) Earth Ground Fig. A. Using an AC voltmeter to check AC leakage. 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. 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. 5