TA-SA300WR
2
1. SERVICING NOTES ............................................. 3
2. DISASSEMBLY
2-1. Disassembly Flow ........................................................... 6
2-2. Front Panel Block, Bottom Panel (L)/(R) ....................... 6
2-3. Case (WLK4), Fuse (F900) ............................................ 7
2-4. WLK4-TERM Board ...................................................... 7
2-5. WLK4 MAIN Board ....................................................... 8
2-6. POWER Board ................................................................ 8
3. TEST MODE ............................................................ 9
4. DIAGRAMS
4-1. Block Diagram ................................................................ 10
4-2. Schematic Diagram - WLK4 MAIN Board (1/2) - ......... 12
4-3. Schematic Diagram - WLK4 MAIN Board (2/2) - ......... 13
4-4. Printed Wiring Board - WLK4 MAIN Board - ............... 14
4-5. Printed Wiring Boards
- WLK4-PANEL, WLK4-TERM Boards - ..................... 15
4-6. Schematic Diagram
- WLK4-PANEL, WLK4-TERM Boards - ..................... 15
4-7. Printed Wiring Board - POWER Board - ........................ 16
4-8. Schematic Diagram - POWER Board - .......................... 17
5. EXPLODED VIEWS
5-1. Panel Section ................................................................... 21
5-2. Main Section ................................................................... 22
6. ELECTRICAL PARTS LIST .............................. 23
TABLE OF CONTENTS
NOTES ON CHIP COMPONENT REPLACEMENT
• Never reuse a disconnected chip component.
• Notice that the minus side of a tantalum capacitor may be dam-
aged by heat.
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 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 2 V AC range are suitable. (See
Fig. A)
1.5 kΩ0.15 μF
AC
voltmeter
(0.75 V)
To Exposed Metal
Parts on Set
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.
ATTENTION AU COMPOSANT AYANT RAPPORT
À LA SÉCURITÉ!
LES COMPOSANTS IDENTIFIÉS PAR UNE MARQUE 0 SUR
LES DIAGRAMMES SCHÉMATIQUES ET LA LISTE DES
PIÈCES SONT CRITIQUES POUR LA SÉCURITÉ DE FONC-
TIONNEMENT. NE REMPLACER CES COMPOSANTS QUE
PAR DES PIÈCES SONY DONT LES NUMÉROS SONT DON-
NÉS DANS CE MANUEL OU DANS LES SUPPLÉMENTS
PUBLIÉS PAR SONY.
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