Section 1 Servicing Notes - Sony ICF-C121 Service Manual

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)
To Exposed Metal
Parts on Set
0.15 µ F
Fig. A. Using an AC voltmeter to check AC leakage.
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-RELATED COMPONENT WARNING!!
COMPONENTS IDENTIFIED BY MARK ! OR DOTTED
LINE WITH MARK ! 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.
SECTION 1
SERVICING NOTES
AC
1.5 k Ω
voltmeter
(0.75 V)
Earth Ground
HOW TO CHANGE THE FM CERAMIC FILTERS
This model is used two ceramic filters of CF1 and CF3.
You must use same type of color marked ceramic filters in order
to meet same specifications.
Therefore, the ceramic filter must change two pieces together since
it's supply two pieces in one package as a spare parts.
mark 1
mark 2
CF1
CORD DRESSING
(POWER, ANTENNA, BATTERY)
1) Connect the power cord, antenna cord, and battery cord as
shown in the figure.
2) Mount the chassis with screws (PTP3 × 10).
Note: Tighten completely the screws (PTP3 × 10).
screw (PTP3 × 10)
ATTENTION AU COMPOSANT AYANT RAPPORT
LES COMPOSANTS IDENTIFIÉS PAR UNE MARQUE !
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.
– 2 –
mark 2
Mark 1 Mark 2
CF3
red —
blue —
orange —
black —
white —
white white
yellow —
battery cord
antenna cord
power cord
chassis
À LA SÉCURITÉ!
Center
frequency
10.70MHz
10.67MHz
10.73MHz
10.64MHz
10.76MHz
10.75 MHz
10.79 MHz