background image
MICROFILM
SERVICE MANUAL
ICF-C793
FM/AM PLL SYNTHESIZED CLOCK RADIO
ICF-C793L
FM/MW/LW PLL SYNTHESIZED CLOCK RADIO
US Model
Canadian Model
Australian Model
ICF-C793
AEP Model
ICF-C793/C793L
UK Model
ICF-C793L
SPECIFICATIONS
ICF-C793/C793L
Photo: ICF-C793L
Ver 1.0 1999. 02


background image
­ 2 ­
TABLE OF CONTENTS
1.
GENERAL ................................................................... 3
2.
DISASSEMBLY ......................................................... 5
3.
ELECTRICAL ADJUSTMENTS ......................... 6
4.
DIAGRAMS
4-1. Block Diagram ................................................................
9
4-2. Printed Wiring Boards .................................................... 11
4-3. Schematic Diagram ......................................................... 13
4-4. IC Pin Function Description ........................................... 16
5.
EXPLODED VIEWS ................................................ 17
6.
ELECTRICAL PARTS LIST ............................... 19
ATTENTION AU COMPOSANT AYANT RAPPORT
À LA SÉCURITÉ!
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.
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.
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 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)
Fig. A.
Using an AC voltmeter to check AC leakage.
1.5 k
0.15
µF
AC
voltmeter
(0.75 V)
To Exposed Metal
Parts on Set
Earth Ground
CF2
CF3
mark
Mark
Center frequency
red
10.70 MHz
blue
10.67 MHz
orange
10.73 MHz
black
10.64 MHz
white
10.76 MHz
HOW TO CHANGED THE CERAMIC FILTERS
This model is used two ceramic filters of CF2 and CF3.
You must used same type of color marked ceramic filters in order
to meet same specifications.
Therefore, the ceramic filter must changed two pieces together
since it's supply two pieces in one package as a spare parts.


background image
­ 3 ­
SECTION 1
GENERAL
This section is extracted from
instruction manual.
LOCATION OF CONTROLS


background image
­ 4 ­


background image
­ 5 ­
CHASSIS ASS'Y
POWER CORD SETTING
Note: Follow the disassembly procedure in the numerical order given.
SECTION 2
DISASSEMBLY
1 screw (P3
× 14)
2 three claws
2 claw
6 button (DST)
5 Break the soldering of
speaker lead.
7 chassis assy
3 rear cabinet
6 knob (brightness)
1 four screws (P3
× 14)
4 connector
(CN301)
rear cabinet
power cord
boss
rear cabinet
power cord
Put the secondary flat cable
between bosses to fix.
Set the power cord as illustrated below,
then install the cabinet.