SA-WM40 — Sony Audio Service Manual (repair manual). Page 2

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2
MODEL  IDENTIFICATION
– Rear View –
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  FONCTIONNEMENT.  NE  REMPLACER  CES  COM-
POSANTS  QUE  PAR  DES  PIÈCES  SONY  DONT  LES
NUMÉROS  SONT  DONNÉS  DANS  CE  MANUEL  OU
DANS  LES  SUPPLÉMENTS  PUBLIÉS  PAR  SONY.
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  PUB-
LISHED  BY  SONY.
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” 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)
Fig. A.
Using an AC voltmeter to check AC leakage.
1.5 k
0.15 
µ
F
AC
voltmeter
(0.75 V)
To Exposed Metal
Parts on Set
Earth Ground
with this indication
: US, Canadian models
without this indication : Except US, Canadian models
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