Sony ICF-M88B Service Manual ▷ View online
ICF-M88B
5
3-4. MAIN BOARD
3-3. CHASSIS ASSY
1
Remove five solders.
4
screw
5
chassis assy
3
button assy
1
Remove two solders.
2
two hooks
3
screw
4
MAIN board
1
Remove the solder.
1
Remove two solders.
2
hook
ICF-M88B
6
POSITION OF LEAD WIRES
three ditches
two ditches
boss
boss
lead wire (battery terminal (+))
cabinet (lower) block
lead wire (red)
lead wire (gray)
lead wire (red)
lead wire (gray)
DX/LOCAL board
lead wire (black)
7
ICF-M88B
TP117
(KR3)
TP115
(KS1)
TP116
(KS0)
IC101
– KEY BOARD (Conductor Side) –
SECTION 4
TEST MODE
EEPROM INITIALIZE MODE
Procedure:
1. Turn on the power to place the set in the standby state.
2. Press the [BAND/SET], [LIGHT] and [MODE/FREEZE] keys
2. Press the [BAND/SET], [LIGHT] and [MODE/FREEZE] keys
simultaneously for 5 seconds, or short the TP116 (KS0) and
TP117 (KR3) on the key board.
TP117 (KR3) on the key board.
3. When the EEPROM initialize mode is activated, the BEEP
1
is outputted and “dEL” is displayed on the LCD for one
second.
4. After one second elapsed, the BEEP 2 is outputted, and the
EEPROM initialize mode is deactivated and the set returns to
the standby state.
the standby state.
LCD AND KEY TEST MODE
Procedure:
1. Turn on the power to place the set in the standby state.
2. Short the TP115 (KS1) and TP117 (KR3) on the key board.
3. When the LCD and key test mode is activated, the BEEP 1 is
2. Short the TP115 (KS1) and TP117 (KR3) on the key board.
3. When the LCD and key test mode is activated, the BEEP 1 is
outputted and the LCD becomes all lit state.
4. Each time a key is pressed, the segment assigned to each key
turns off (see below). Also, if the [LIGHT] key is pressed, the
LCD back light turns on. (It turns off at the release of LCD
and ket test mode)
LCD back light turns on. (It turns off at the release of LCD
and ket test mode)
5. When all keys were pressed, the BEEP 2 is outputted, and
the LCD and key test mode is deactivated and the set returns
to the standby state.
to the standby state.
Note 1:
The pulse input is ignored during each test mode.
Note 2:
In the event that the VDET1 terminal (pin rl of IC101) on the key
board detects “L” during each test mode, the test mode is deactivated
and the set returns to the standby state.
board detects “L” during each test mode, the test mode is deactivated
and the set returns to the standby state.
Note 3:
The amplifier power turns on by the main clock operation to prepare
for the BEEP output during each test mode.
for the BEEP output during each test mode.
Key
Segment
Display
POWER
S0, S2, S4
below LCD display-1
TUNE MODE
S6, S8, S10
below LCD display-2
BAND/SET
S12, S14, S16
below LCD display-3
+
S18, S20, S22
below LCD display-4
–
S3, S5, S7
below LCD display-5
RESET
S9, S11, S13
below LCD display-6
MODE/FREEZE
S15, S17, S19
below LCD display-7
ENTER/SELECT
S21, S23, S25
below LCD display-8
LIGHT
S1, S24
below LCD display-9
MPH
AM
PM
FM
FREEZE
PRESET
MHz
MHz
MPH
kHz
km/h inch
AM
km/h
mile
CLOCK ODO DIST RT AVG MAX
mm
LCD display
MPH
kHz
km/h inch
LCD display-1
mile
RT AVG MAX
LCD display-2
AM
PM
CLOCK ODO
LCD display-3
DIST
LCD display-4
MPH
FM
AM
km/h
mm
LCD display-5
FREEZE
LCD display-6
PRESET
MHz
MHz
LCD display-7
LCD display-8
LCD display-9
Connecting Location:
8
ICF-M88B
AM IF ADJUSTMENT
Adjust for a maximum reading on level meter
T1
450 kHz
AM VCO VOLTAGE ADJUSTMENT
Adjustment Part
Frequency Display
Reading on Digital Voltmeter
L1
530 kHz
1.2
± 0.1 V
Confirmation
1,710 kHz
7.2
± 0.5 V
AM TRACKING ADJUSTMENT
Adjust for a maximum reading on level meter
ANT1
590 kHz
CT1
1,490 kHz
FM VCO VOLTAGE ADJUSTMENT
Adjustment Part
Frequency Display
Reading on Digital Voltmeter
Confirmation
108.0 MHz
8.9
± 1.0 V
Confirmation
87.5 MHz
2.3
± 0.5 V
FM TRACKING ADJUSTMENT
Adjust for a maximum reading on level meter
L2
87.5 MHz
CT2
108.0 MHz
Adjustment Location: MAIN board (See page 9)
0 dB=1
µ
V
[AM]
Setting:
Function: RADIO
BAND: AM
Function: RADIO
BAND: AM
[FM]
Setting:
Function: RADIO
BAND: FM
Function: RADIO
BAND: FM
• Repeat the procedures in each adjustment several times, and
the tracking adjustments should be finally done by the trimmer
capacitors.
capacitors.
• Remove FM antenna in FM adjustment.
AM RF signal
generator
30% amplitude
modulation by
400 Hz signal
Output level:
as low as possible
modulation by
400 Hz signal
Output level:
as low as possible
Put the lead-wire
antenna close to
the set.
antenna close to
the set.
+
–
–
level meter
set
8
Ω
MAIN board
TP15 (AF GND)
TP15 (AF GND)
MAIN board
TP12 (SP OUT)
TP12 (SP OUT)
FM RF signal
generator
22.5 kHz frequency
deviation by 400 Hz
signal
Output level:
as low as possible
deviation by 400 Hz
signal
Output level:
as low as possible
+
–
–
level meter
MAIN board
TP15 (AF GND)
TP15 (AF GND)
MAIN board
TP12 (SP OUT)
TP12 (SP OUT)
set
8
Ω
0.01
µ
F
MAIN board
TP10 (RF GND)
TP10 (RF GND)
MAIN board
TP13 (FM IN)
TP13 (FM IN)
digital voltmeter
TP9 (VT)
TP8 (GND)
100 k
Ω
MAIN board
SECTION 5
ELECTRICAL ADJUSTMENTS
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