MICROFILM
SERVICE MANUAL
FM/AM RADIO
AEP Model
UK Model
E Model
Australian Model
ICF-28
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.
SPECIFICATIONS
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 CHANGE 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.
Ver 1.1 1998. 09
2
SECTION 1
GENERAL
This section is extracted from
instruction manual.
3
CABINET (REAR) ASSY
Note: Follow the disassembly procedure in the numerical order given.
SECTION 2
DISASSEMBLY
POINTER SETTING
6 cabinet (rear) assy
8 lug, 3
2 two claws
1 claw
9 telescopic antenna
5 claw
!¡ INLET board
3 lid, battery case
4 four screws
(BTP3
× 14)
4 two screws
(BTP3
× 14)
!º two screws
(P3
× 10)
7 screw
(P2.6
× 8)
5 Mount the pointer
3 two claws
3 claw
2 knob (TUNE)
1 Turn CV1 fully in
the arrow direction.
6 Insert the pointer to the knob (TUNE)
fitting the concave position of the pointer
to the convex position of the knob (TUNE).
4 chassis
4
0 dB = 1µV
[FM]
Setting:
Band switch: FM
[AM]
Setting:
Band switch: AM
· Repeat the procedures in each adjustment several times, and the
frequency coverage and tracking adjustments should be finally
done by the trimmer capacitors.
· Remove FM antenna in FM adjustments.
Adjustment Location:
FM FREQUENCY COVERAGE ADJUSTMENT
Adjust for a maximum reading on level meter.
L3
86.5 MHz (64.0MHz)
CT3
109.5 MHz
FM TRACKING ADJUSTMENT
Adjust for a maximum reading on level meter.
L2
86.5 MHz (64.0MHz)
CT2
109.5 MHz
AM FREQUENCY COVERAGE ADJUSTMENT
Adjust for a maximum reading on level meter.
L4
520 kHz
CT4
1,750 kHz
AM TRACKING ADJUSTMENT
Adjust for a maximum reading on level meter.
L1
600 kHz
CT1
1,400 kHz
AM IF ADJUSTMENT
Adjust for a maximum reading on level meter.
T1
455 kHz
SECTION 3
ELECTRICAL ADJUSTMENTS
(
): East European model
FM RF signal
generator
22.5 kHz frequency
deviation by 400 Hz
signal
Output level: as low as possible
+
level meter
speaker terminal
set
FM antenna terminal
4
0.01
µF
AM RF signal
generator
30% amplitude
modulation by
400 Hz signal
Output level: as low as possible
Put the lead-wire
antenna close to
the set.
+
level meter
speaker terminal
set
4
CT3
L3
FM Frequency
Coverage
Adjustment
CT4
L4
AM Frequency
Coverage
Adjustment
FM Tracking
Adjustment
L2
CT2
FM
Antenna in
AM Tracking
Adjustment
L1
CT1
IC1
Speaker in
T2
T1
AM IF
Adjustment
[MAIN board]
(Component Side)
9
SECTION 5
EXPLODED VIEW
The components identified by
mark
! or dotted line with mark
! are critical for safety.
Replace only with part number
specified.
· Items marked "*" are not stocked since they
are seldom required for routine service. Some
delay should be anticipated when ordering
these items.
· The mechanical parts with no reference num-
ber in the exploded views are not supplied.
· Accessories and packing materials are given
in the last of the electrical parts list.
NOTE:
· -XX and -X mean standardized parts, so they
may have some difference from the original
one.
· Color Indication of Appearance Parts
Example:
KNOB, BALANCE (WHITE) . . . (RED)
Parts Color Cabinet's Color
Ref. No.
Part No.
Description
Remark
Ref. No.
Part No.
Description
Remark
· Abbreviation
AR
: Argentina
AUS : Australian
EE
: East European
1
3-026-251-01 SCALE, DIAL
2
3-026-249-01 CABINET (FRONT)
3
3-908-109-11 POINTER
* 4
3-908-107-02 CHASSIS
* 5
1-670-706-11 INLET BOARD
6
7-685-647-79 SCREW +P 3X10 TYPE2 NON-SLIT
* 7
3-908-115-01 TERMINAL (+), BATTERY
* 8
3-908-116-01 SPRING (), BATTERY COIL
9
7-685-134-19 SCREW +P 2.6X8 TYPE2 NON-SLIT
10
7-623-508-01 LUG, 3
11
3-029-028-01 TERMINAL (+/), BATTERY
* 12
3-908-130-01 HANDLE
13
7-685-549-11 SCREW +BTP 3X14 TYPE2 N-S
14
3-026-250-01 CABINET (REAR)
15
3-026-252-01 LID, BATTERY CASE
* 16
A-3683-007-A MAIN BOARD COMPLETE (AEP, UK, AR, AUS)
* 16
A-3683-008-A MAIN BOARD COMPLETE (EE)
17
3-908-111-01 KNOB (VOL)
18
3-908-110-01 KNOB (TUNE)
19
3-026-254-01 KNOB (POWER)
20
3-026-253-01 KNOB (BAND)
ANT1
1-501-222-81 ANTENNA, TELESCOPIC (FM)
D3
8-719-042-69 LED LN21RPL (TUNE)
J101
1-526-838-11 INLET, AC 2P
SP1
1-544-518-11 SPEAKER
! T2
1-450-324-21 TRANSFORMER, POWER