SONY SWUS501
Manual de Servicio

SS-US501/SW-US501/UZ-US501

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. SAFETY CHECK-OUT After correcting the original service problem, perform the following safety check 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 TEST 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 lowvoltage 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 2 V AC range are suitable. (See Fig. A)
To Exposed Metal Parts on Set

UNLEADED SOLDER Boards requiring use of unleaded solder are printed with the leadfree mark (LF) indicating the solder contains no lead. (Caution: Some printed circuit boards may not come printed with the lead free mark due to their particular size) : LEAD FREE MARK Unleaded solder has the following characteristics. � Unleaded solder melts at a temperature about 40 �C higher than ordinary solder. Ordinary soldering irons can be used but the iron tip has to be applied to the solder joint for a slightly longer time. Soldering irons using a temperature regulator should be set to about 350 �C. Caution: The printed pattern (copper foil) may peel away if the heated tip is applied for too long, so be careful! � Strong viscosity Unleaded solder is more viscou-s (sticky, less prone to flow) than ordinary solder so use caution not to let solder bridges occur such as on IC pins, etc. � Usable with ordinary solder It is best to use only unleaded solder but unleaded solder may also be added to ordinary solder.

0.15 µF

1.5 k�

AC voltmeter (0.75 V)

Earth Ground
Fig. A. Using an AC voltmeter to check AC leakage.

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.

2