Onkyo TX-7230 User manual

SERVICE
MANUAL
QUARTZ
SYNTHESIZED
|
TUNER
AMPLIFIER
MODEL
TX~7230
Silver and b:
SAFETY-RELATED COMPONENT WARNING!!
COMPONENTS IDENTIFIED BY MARK Z\ ON
THE SCHEMATIC DIAGRAM AND IN THE PARTS
LIST ARE CRITICAL FOR RiSK OF FIRE AND
ELECTRIC SHOCK. REPLACE THESE COMPO-
NENTS WITH ONKYO PARTS WHOSE PARTS
NUMBERS APPEAR AS SHOWN IN THIS MANUAL.
MAKE LEAKAGE-CURRENT OR RESISTANCE
MEASUREMENTS TO DETERMINE THAT EX-
POSED PARTS ARE ACCEPTABLY INSULATED
FROM THE SUPPLY CIRCUIT BEFORE RETURN.
ING THE APPLIANCE TO THE CUSTOMER.
i
mocels
TABLE OF CONTENTS
Spectiications . 00 ce ee oe 2
Service procédures... 2s ee poe ee 3
Biock diagrani
Amplifier section. «2. ee eee 4
Power supply section. 2... 0. ee 4
Dynaznic bass ciretitusc0.. oo oe oe 4
Pune? section) oe ee 5
Exploded view. 2.22 ee ee 6
Paris list. 0 ee ee, Gy ees 7
Circuit description. oe ee oe 8
Adjustment procedures... 65. oe 13
Pcb view/list
Tuner section 2 0. ee ee ee, 15
Digital section. 6. ee bye ee 17
Aimplifier section... oe 21
Control section... ee ee 25
Senematic diagram
Jumer section 3. 2k eee oe 19
AMD, section 4. lee ee ee, 2.
Block diaprani of 1Co 0 ee, head
Packing View. 2. 0 See ee ee. 2

TX~7230
SPECIFICATIONS
AMPLIFIER SECTION
Power Output:
Musical Power Output:
Continuous Power Output:
Total Harmonic Distortion:
IM Distortion:
Damping Factor:
Frequency Response:
RIAA Deviation:
Sensitivity and Impedance:
Phono Overload:
Signal-to-Noise Ratio:
Tone Controls:
Loudness (—30dB):
Subsonic:
TUNER SECTION
FM:
Tuning Range:
Usable Sensitivity:
50dB Quieting Sensitivity:
Capture Ratio:
Image Rejection Ratio:
IF Rejection Ratio:
Signal-to-Noisc Ratio:
Selectivity:
AM Suppression Ratio:
Harmonic Distortion:
Frequency Response:
Stereo Separation:
Tuning Level(Hi/Lo):
Muting Level:
Stereo Threshold:
AM:
Tuning Range:
Usable Sensitivity:
Image Rejection Ratio:
IF Rejection Ratio:
Signal-to-Noise Ratio:
Harmonic Distortion:
GENERAL
Semiconductors:
Dimensions (WX HXD):
Weight:
40 watts per channel, min RMS, at 8 ohms,
both channels driven, from 20Hz to 20kHz,
with no more than 0.04% THD.
2 x 85 watts at 4 ohms, 1kHz (DIN)
2 X 55 watts at 8 ohms, 1kHz (DIN)
2 x 55 watts at 4 ohms, 1kHz (DIN)
2 x 40 atwatts ato at 8 ohms, 1kHz (DIN)
0.08% at rated power
0.08% at 1 watt output
0.08% at rated power
0.08% at 1 watt output
35 at 8 ohms
20 — 30,000 Hz + 1 dB
20 — 20,000 Hz + 0.8dB
Phono: 2.5mV/50 kohms
CD/Tape Play: 150mV/50 kohms
Tape Rec: 150mV/3.5 kohms (phono)
180mV RMS at 1 kHz, 0.04% THD
Phono: 85dB (at 10mV input, A weighted)
76dB ({HF A-202)
CD/Tape: 95dB (A weighted)
80dB (IHF A-202)
Bass: + 10dB at 100Hz
Treble: + 10dB at 10kHz
+7 dB at 70 Hz, +5 dB at 10kHz
~—6 dB at 15 Hz
87.5 — 108.0 MHz (SOkHz steps)
Mono: 12.8dBf, 1.2uV, 75 ohms
1.0uzV (S/N 26dB, 40kHz Devi.)
75 ohms DIN
Stereo: 18.0dBf, 2.2uV, 75 ohms
23uV (S/N 46dB, 40kHz Devi.)
75 ohms DIN
Mono: 18.0dBf, 2.2uV 75 ohms
Stereo: 37.2dBf, 20uV, 75 ohms
1.5dB
85dB
90dB
Mono: 71dB
Stereo: 66dB
50dB DIN (+300kHz, 40kHz dev.)
50dB
Mono: 0.15%
Stereo: 0.3%
30 — 15,000Hz + 1.5dB
40dB at 1kHz
30dB at 100 — 10,000Hz
17.2dBf, 2uV
17.2dBf, 2uV
§22 — 1611kHz (9kHz steps)
30uV
40dB
40dB
40dB
0.8%
FETs: 7 TR: 37 ICs: 10
Diodes: 54 LEDs: 28
435 x 112 X 343 mm
17-1/8” x 4-7/16” X 13-1/2”
7.8 kg 17.2 Ibs.
Specifications
and
features
are
subject
to
change
without
notice.

SERVICE PROCEDURES
1. Replacing the fuses
For continued protection against fire hazard, replace
only with same type and same rating fuse.
Circuit no. Partsno. Description
F501, F601 252076 3.15A-SE-EAK, Primary
F902 252074 2A-SE-EAK, Primary
F903, F904 252078 5A-SE-EAK, Secondary
F905 252070 1A-SE-EAK, Secondary
‘2. Replacing the lamp
This unit uses the lamp listed below.
Circuit no. Partsno. Desciption
PL901 210064A PL 6.3V, 250mA, Dial
plate illumination
3. Removement of display pc board
@. Remove the five screws holding the top cover and
chassis (side bracket:4 back panel: 1), and remove
the top cover.
Remove the five screws holding the front panel
and front bracket, and remove the front panel.
Remove the two screws holding the switch pc
board and front bracket, and remove the switch pc
board of U4.
Remove the four screws holding the holder and
front bracket.
Remove the display pc board ass’y from the four
nails of holder, and remove the holder.
Remove the two knobs (A805).
Remove the two screws holing the NAAF—2306 pc
Board ass’y and center bracket, and remove the
NAAF—2306.
© e
SO: 2.
@
dynamic bass expander and front bracket, and
remove the display pce board.
4. Memory Preservation
This unit does not require memory preservation bat-
teries. A built-in memory power back-up system preser-
ves contents of the memory during power failures and
even when the unit is unplugged. The unit must be plug-
ged in and the power switch turned on and off once in
order to charge the back-up system. Note that since this
is not a permanent memory, the power switch must be
turned on and off a few times each month to keep the
back-up system operable. The period of time during
witch memory contents are preserved after power has
last been turned off varies depending on climate and the
location and placement of the unit. On the average,
memory contents are protected over a period of 3 to 4
weeks (a minimum of 2 weeks) after the last time
power has been turned off. This period is shorter when
the unit is exposed to very high humidity or used in an
area with an extremely humid climate.
Remove the two screws holding the switch of
F501 F601
Speaker
protection
fuse
F902 F904 F903
: <G/W>
Pri. = TES il il
<G>
F901 <pjw>
F905
<G> Second.
- a7 A16
“n805)i \
A805)ago6) Jt —
(ur 27
G28)

TX-7230
BLOCK DIAGRAM
—AMPLIFIER SECTION—
TUNER
o
BASS
TREBLE
VOLUME
Sel}
pal
S2
BALANCE RS)
LOUDNESS
Q301
EQUALIZER
AMP
~ 2301 $303
SELECTOR
PHONOO)
SOURCE
INDICATOR »
To.Rch
co.
POWER SPEAKER:
mReC
QO——+~—____}_
pre
t_-
AMP
PROTECTION
TAPE-1
aaa
PB
HE ADPHONE
p-REC
TAPE-2
tpa O—
Q9210922
SPEAKER A
QS23
DY NAMIC
BASS
€ XPANDER
owt LEVEL °
*
SPEAKER B
—POWER SUPPLY SECTION—
To FLUORESCENT
INDICATOR
TUBE
—DYNAMIC BASS EXPANDER—
OUTPUT
D521,
D522
RECTIFIER
FILTER
other channel i. other channel
In
earlier
super
base
systems,
only
the
frequencies
about
70Hz
were
boosted
by
about
4dB
to
expand
the
playback
frequ-
ency
response
to
enable
playback
of
the
super
low
region.
However,
when
there
was
no
input
signal,
the
above
frequency
response
resulted
in
deterioration
in
the
S/N
ration
in
the
70Hz
region.
This
problem
has
been
overcome
by
the
dynamic
bass
expander
where
the
70Hz
boosted
level
is
varied
according
to
the
input
signal
level.
That
is,
the
frequency
response
remains
flat
when
no
input
signalis
applied,
but
is
boosted
at
the
70Hz
region
to
the
specified
level
when
the
input
signal
exceeds
a
certain
level.
The
left
and
right
channel
input
signals
from
the
INPUT
terminals
are
mixed
by
Q523
and
pass
through
the
level
volume
and
filter
amplifier.
The
signal
is
rectified
by
D551
and
D552,
and
the
resultant
DC
component
control
signal
is
applied
to
the
gate
of
Q525.
When
the
input
signal
is
at
a
adequate
level,
Q525
is
turned
on
and
the
super
base
circuit
of
power
amplifier
is
controlled
by
the
input
signal.

BLOCK DIAGRAM
—TUNER SECTION—
NARF - 23020!
L302
8 CT + SR | : LET
H | JFeceu23 | gt.
a ASENNA i j .
x101 @101-x102, Q102,—Ssx103 hee L201 : 1p.
TERMINAL RF FM iF FM tf FM IF FM IF EM IF 2 DIROIE a 4
MIXER IFT FILTER AMP FILTER AMP FILTER FILTER
Q20)
STEREO CECQDER
FM IF SYSTEM
(AMP.,MUTING, METER & DET. }
150|
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yw
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ira
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z
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re)
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zr
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AMP
ANTENNA TUNED TUNED
CIRCUIT 2 CIRCUIT CIRCUIT
£103,107
NOISE
DETECTOR
BUFFER
zg (76KHz) I
R203
SEPARATION
L203
202 F
GATE
cirRcult &
IF AMP. OFF
AM LOOP
ANTENNA
Q1s1
AM RADIO SYSTEM
aiss 106
GATE
CIRCUIT
Q205
GATE
ciRcult
X1S)
AM IF
FILTER
GATE
CIRCUIT
TUNED
CIRCUIT
B g=8
Os:
2
on
zz
3
Q208
MUTING
C) C ) Swi TCH
Q706
AUTO-STOP
SWITCH
Q701 @ l-Our
PRESCALER
Q704,0708
LOW PASS
FILTER
ey R-OUT
Q703
STATIC FREQUENCY
ORIVER
Q702
PLL SYNTHESIZER & CONTROLLER
id, daeadecedes i :
42
STEREO @)
AUTO
SwiTCH
SWITCH
ons
merce — @avze FaSPeseR”
zj)=z INOICATOI
a a = 2 Stale SWITCH pert
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2 PS Fe 2 SWITCH — —
Fees 2 FA < EM +8 FM MH
fia = 2 = SWITCH z
AM PETA LAT se
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soe 7 ae tures
NADG-23030
CRCUIT
L
fio
: : {nicaroal
SWITCH
Q709
GATE
CIRCUIT
GATE
CIRCUIT
+ Q710
5OKHz
.
Inpicaror”
)
SWITCH

TX-7230
EXPLODED VIEW

PARTS LIST
REF. NO. PART NO. DESCRIPTION REF. NO. PART NO. DESCRIPTION REF. NO. PART NO. DESCRIPTION
Al 27110243 ‘Front bracket ASOle 28322012A Selector knob ass’y Ul 18454502D NARF-2302D, Tuner circuit pc board
A2 27190198A Holder, lamp ASOIf 28322018A Knob ass’y ass’y
A4 28133132A Back plate A511 838430068 3TTB+6B(BC), Tapping screw U2 18454503D NADG, 2303D, Digital circuit pc board
AS 28130225B Dial plate A601 27170198A Bottom board ass’y
A6 27190358A Holder A602 27175009A Leg U4 18408505 NASW-2305, Operation switch pc board
AT 27260171B Shaft A603 834430068 3TTS+6B(BC), Tapping screw ass’y
A8 27220032A Slider A604 834430128 3TTS+12B(BC), Tapping screw US 18448506A NAAF-2306A, Dynamic bass circuit
A9 27190359A Holder, dial A701 27267402A Guide, decoration pe board ass’y
Al0 28198632 Facet A803 28321928 Knob, power <S) U6 18414507A NAEQ-2307A, Equalizer amplifier pc
Al2 27115180 Side bracket R 28321905B Knob, power (B) board ass’y
Al4 27130388 Bracket, power transformer A804 28321886 Knob, speaker (S) U7 18414508A NASW-2308A, Source selector switch pc
Al6 27130390 Bracket, center 28321894 Knob, speaker (B) board ass’y
Al7 27190011 Holder A805 28322005A Knob, expander U8 18454509D NAAF-2309D, Power amplifier and power
Al9 27160174 Radiator A806 28322006 Knob, slide power supply pc board ass’y
A21 27260172 Shaft A807 28322007A Knob, loudness (S) . U9 18408510 NATC-2310, Tone control circuit pc
A22 28320135 Connector 28322020A Knob, loudness (B) board ass’y
A24 27120684 Back panel A808 28321887A Knob, volume <S) U10 18448511A NASW-23114A, Switch pc board ass’y
A25 27130389B Bracket B 28321895 Knob, volume (B) Uil 18408512 NASW-2312, Speaker switch pc board
A26 A 27300750 — Strainrelief A809 28322008 Knob, balance (S) ass‘y
A28 27273030C Joint L 28322021A Knob, balance (B) U12 18408513. NAHP-2313, Headphone terminal pc
A30 27150202 Shielded plate A810 28322009A Knob, shift <S) board ass’y
A38
834430068
3TTS+6B(BC),
Tapping
screw
28322022A
Knob,
shift
(B)
U13
18408514
NAVR-2314,
Volume
control
pc
board
A40 : 831130088 3TTW+8B, Tapping screw F501 252076 3.15A-SE-EAK, Speaker protecion ass’y
A41 838440089 4TTB+8C(BC), Tapping screw F601 fuse u14 18414516 NAPL-2316, Edge light pc board ass’y
A42 834430168 3TTS+16B(BC), Tapping screw F902 A, 252074 2A-SE-EAK, Primary fuse
A44 834430108 3TTS+10B(BC), Tapping screw F903 A\ 252078 5A-SE-EAK, Secondary fuse
A46 82142003 2P+3F(BC), Pan head screw F904
A47 82143006 3P+6FN(BC), Pan head screw F905 A 252070 1A-SE-EAK, Secondary fuse
ASO 880004 Rivert P904 25060044 Terminal GND
A301 28184271 Top cover (S) P906 253128 AS AS-CEE, Power supply cord
28184272 Top cover <B> Q501 222041 STK4843, Power amplifier IC
A302 834430068 3TTS+6B(BC), Tapping screw Q901 222780122 78M12, Constant voltage IC
A501 18452121 Front panel ass’y (S) T901 232085 NMA-3034, AM loop antenna
A5Ola 27267387 Guide, speaker T901la 27190105 Holder, antenna
A501b 27267386B Guide, power T902 Z\ 230870A NPT-875G, Power transformer
A501c 27267398 Guide, loudness
ASOid 28191293B Clear plate
ASOle 28321992A° Selector knob ass’y
ASOILf 28321998A Knob ass’y
A501 18472121 Front panel ass’y (B)
ASOla 27267390 Guide, speaker
A5S01b 27267389B Guide, power
AS01c 27267399 Guide, loudness
A50ld 28191295C Clear plate
NOTE: THE COMPONENTS IDENTIFIED BY MARK
NOTE: | #. ARE CRITICAL FOR RISK OF FIRE AND
{S): Only silver model ELECTRIC SHOCK. REPLACE ONLY WITH
<B): Only black model PARTS NUMBER SPECIFIED.

TX-7230
CIRCUIT DESCRIPTIONS
1. Synthesizer and controller operation
Pin
No.
{|
Symbol
Terminal
Description
1
GND
Ground
2
XT
X’tal
Connected to the 7.2MHz crystal oscillator for the reference frequency.
FM band specification
input
MW band specification
input
LW band specification
input
Mutual reset type, performs switching of each band, FM/MW/LW.
Manual tuning mode
specification input
MANUAL
—-|-__—
8 AUTO
specification input
Auto search tuning mode
Mutual reset type, performs auto search and manual operation mode
switching during UP/DOWN tuning.
p10 DOWN DOWN tuning key input
Memory store command
input
Preset memory channel
a a a specification input
Connect the push key and perform UP/DOWN tuning.
The preset memory is set to the write mode when the key is pressed.
Controls the write and read out of the internal 16-station preset
memory along with the MC] and MC2 input.
MC-1
Set the
16-station
preset
memory
to
the
8
FM/8
AM
station
mode
or
Memory
control
input
the
FM/MW/LW
3-band
16-station
random
mode.
The
8
FM/8
AM
MC-2
mode
is
used
in
this
unit.
Osc?
AM
oeallaton
eaaninal
CR
connection
terminal
for
the
oscillator
that
determines
the
scan
speed
during
the
AM
search
mode.
—t
al
2
:
:
CR
connection
terminal
for
the
oscillator
that
determines
the
scan
os!
le
oscillator
terminal
speed
during
the
FM
search
mode.
Output
that
represents
the
SOkHz
FM
band
tuning
step
for
European
o/s
EM
SORHE
output
models.
Goes
to
the
high
level
for
the
50
kHz
setting.
7
CK2
CK
Tuned
frequency
Outputs
the
serial
data
and
timing
clock
to
the
tuned
frequency
display
data
output
driver.
28
MUTE
Muting
signal
output
Goes
to
the
high
level
during
muting
output.
Regin specification input
29 E2
30 El
See table 1.
AM IF signal input
ae |
31
STOP
3
During
AM
reception,
this
counts
the
IF
signal
and
stops
auto
search.
ae
;
3
STOP
2
Auto
search
stop
When
the
stop
|
input
(pin
33)
is
at
the
high
level
and
this
terminal
2
signal
input
goes
to
the
high
level,
auto
search
is
stopped.
|
=,
: .
. .
*
d
.
33
STOP
1
Scan
speed
slow
input
When
the
high
level
is
input
at
this
terminal,
the
auto
search
speed
is
cut in half.

Pin No. | Symbol Terminal Description
bs { fe
Charge pump output of the phase detector which constitutes the PLL.
34 DOI High level is output when the divided oscillation frequency is high than
: the reference frequency. In the opposite case, low level is output.
{— —} Error output Floating occurs when the frequencies match. The output is applied to
the variable capacitor diode in the front end through low pass filter
35 DO2 Q704 and Q705. The output from both terminals is the same, but
only DOI is used.
{
36 TEST Test terminal Test mode at the high level.
+}
}..__-_-—
-
7 FM programmable “
37 FM IN counter input Connect to the prescaler output (Pin3 of Q701) |
38 PSC ra a control Output to the control the division ratio of the prescaler.
ie
AM
local
oscillator
:
‘ :
39
AM
IN
signal
input
Terminal
for
input
of
AM
broadcast
signal.
40
INH
Inhibit
input
Operates
normally
at
the
high
level.
Inhibit
status
at
the
low
level.
_. 4 1
.. int idsialigetasat Operates normally at the high level. At the low level, the internal status
a a is initialized.
ea? Mog eee le | ‘Pewee power terminal; : supplies 5V during the normal operation and
42 Yee Power stply 2.5V from the super capacitor (C712) for memory preservation.
be
table |.
E]
E2
ei
Bane
i
Frequency
Intermediate
Reference
(Pin
30)
(Pin
29)
pa
a
range
frequency
step
frequency
-+—--_—_—___--—_}. fp —
FM 87.5 ~ 108.0 MHz +10.7 MHz 100 kHz 25 kHz
0
l
foes
ht
ong
SO
U.S.A
AMI
520
~
1
710
kHz
+450
kHz
10kHz
10
kHz
ak eles | eeeseen
|
l
AM2
522
~
1710
kHz
+450
kHz
9kHz
9kHz
| FM +10.7MHz | SO kHz 25 kHz
fe a ee
]
0
Europe
|
MW
522
~
1611
kHz
+450
kHz
9
kHz
9
kHz
LM 153 ~ 360 kHz +450 kHz 1 kHz
_t
FM 76.0 ~ 90.0 MHz - 10.7 MHz 100 kHz
0 0 Japan i.
AM 522 ~ 1611 kHz +450 kHz 9 kHz
2. Auto Hi-blend switch circuit
The
Q103
FM
IF
system
incorporates
IC’s
with
a
built-in
IF
level
detector
with
a
13
pin
output.
If
an
input
above
38dB
enters
the
antenna,
Q205
is
turned
on,
and
Q721
is
turned
on,
the
Q722
and
Q202
are
turned
off
and the
high
blend
function
is
turned
off.
—9—

TX-7230
3. Auto search tuning circuit
Q103
FM IF
SYSTEM
TO
STEREO
DECODER
D811
Ww WwW
0702
CONTROLLER
Q806
NOISE
DETECTOR
From
AM IC
To :
Signal
indicator
circuit
Maximum frequency
Station B
Station A
Start
Minimum frequenc
= a (fig. 4)
4. FM/AM switch circuit
+B Q702
Q155
Q709 (ON
The FM/AM selector circuit is shown in the diagram. fig.5.
Pins 4 and 5 of Q702 are of the mutual reset type. For FM,
pin 4 is high and pin 5 is low; for AM, pin 4 is low and pin
5 is high. Because pin 5 is high and pin 4 is low during AM
reception, Q709 is off, the AM, kHz segments of the fluores-
cent display are turned on. Also, since Q708 goes to on and
Q714 is turned off, and the FM indicators are turned off.
At the same time, Q155 is turned off and Q154 turned on,
so
+B
is
supplied
to
the
power
source
terminal
of
the
radio
Q154
To AM/kHz segment
To FM/MHz segment
During FM reception, this is operated by the IF level detec-
tion and zero point detection circuits included in the FM IF
system IC of Q103 and by the noise component detection
circuit
of
Q806.
When
a
station
is
tuned,
the
output
of
all
outputs
go
to
the
low
level
so
Q843
goes
from
on
to
off,
causing
pins
32
and
33
of
the
controller
IC
to
go
to
the
high level to complete auto search tuning.
During AM reception, this is operated by the IF level detec-
tion included in the AM radio system IC of Q151. When a
station is turned, Q152 goes from off to on and Q706 goes
to off, causing pins 32 and 33 of the controller IC to go to
the high level to complete auto search tuning.
@ Manual Tuning
When the UP or DOWN key is pressed, the frequency
goes up or down by one step. When either key is held
down, the frequency rapidly increases or decreases
(scans) and stops when the key is released. When either
end of the turning range is reached, key input will no
longer be received and the frequency will stop at the
highest or lowest frequency.
e@ Auto Tuning
When the UP or DOWN key is pressed, scanning begins
in the up or down direction, stopping where there is a
radio station. Since auto scan is operated by a trian-
gular
wave,
scanning
is
begun
in
the
opposite
direction
the instant either end of the tuning range is roached.
Also, if the UP or DOWN key is pressed when the tuned
frequency is not at either end of the range, up or down
scanning will begin.
Pin 16 of Q201
VCO stop terminal
of stereo decoder
Pin 2 of Q103
FM IF Amp,
stop inpu
Muting circuit
——— -
D119
Q108
Pins 8 & 14
AM B+ Terminals
( ): FM reception
from A. G. C detector circuit
(fig. 5}
system pins 8 & 14 of QIS].
Pin
16
of
Q201
goes
to
the
high
level,
the
VCO
oscillator
stops,
and
pin
2
of
Q103
gose
to
the
high
level
so
the
FM
IF
amp
is
also
switched
off.
Also,
during
AM
reception,
Q108
is
turned
on
so
the
muting
circuit
is
off.
During
FM
reception,
all
of
the
switching
transistors
mentioned
above
perform
the
opposite
operations
to
switch
to
the
FM
mode.
Figures
in
parenthese
indicate
transistor
Operation
during
FM
reception.
—10—