Sony sa wmsp 68 service manual
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2 1.5 k Ω 0.15 µF AC voltmete r (0.75 V) To Exposed Metal Parts on Set Earth Ground SAFETY CHECK-OUT After correcting the original service problem, perform the follow- ing 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 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 indica- tion is 0.75 V, so analog meters must have an accurate low- voltage scale. The Simpson 250 and Sanwa SH-63Trd are ex- amples of a passive VOM that is suitable. Nearly all battery operated digital multimeters that have a 2 V AC range are suit- able. (See Fig. A) 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. TABLE OF CONTENTS 1. DIAGRAMS 1-1. Note for Printed Wiring Boards and Schematic Diagrams ............................................................ 3 1-2. Circuit Boards Location ...................................................... 3 1-3. Schematic Diagram – Main Section – ................................. 5 1-4. Printed Wiring Boards – Main Section – ............................ 6 2. EXPLODED VIEWS 2-1. Front Section ....................................................................... 7 2-2. Rear Section ........................................................................ 8 3. ELECTRICAL PARTS LIST ........................................... 9 SA-WMSP68 - UNLEADED SOLDER Boards requiring use of unleaded solder are printed with the lead- free 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 viscous (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. (Fig. A)
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3 SA-WMSP68 1-1. NOTE FOR PRINTED WIRING BOARDS AND SCHEMATIC DIAGRAMS 1-2. CIRCUIT BOARDS LOCATION SECTION 1 DIAGRAMS THIS NOTE IS COMMON FOR PRINTED WIRING BOARDS AND SCHEMATIC DIAGRAMS. (In addition to this, the necessary note is printed in each block.) For schematic diagrams. Note: -All capacitors are in µF unless otherwise noted. (p: pF) 50 WV or less are not indicated except for electrolytics and tantalums. -All resistors are in Ω and 1/4 W or less unless otherwise specified. -C: panel designation. For printed wiring boards.Note: -X: parts extracted from the component side. -Y: parts extracted from the conductor side. - : Pattern from the side which enables seeing. -A: B+ Line. -B: B– Line. -Voltages are dc with respect to ground under no-signal (detuned) conditions. no mark : Power on -Voltages are taken with a VOM (Input impedance 10 MΩ). Voltage variations may be noted due to normal produc- tion tolerances. -Signal path. F: AUDIO Note:The components identified by mark 0 or dotted line with mark 0 are critical for safety. Replace only with part number specified. MAIN board CONTROL board POWER TRANS boar d POWER AMP board SWITCH board