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AM/FM STEREO TUNER

TX-497 SERVICE MANUAL


IMPORTANT NOTICE
This manual has been provided for the use of authorized YAMAHA Retailers and their service personnel.
It has been assumed that basic service procedures inherent to the industry, and more specifically YAMAHA Products, are already
known and understood by the users, and have therefore not been restated.
WARNING: Failure to follow appropriate service and safety procedures when servicing this product may result in personal
injury, destruction of expensive components, and failure of the product to perform as specified. For these reasons,
we advise all YAMAHA product owners that any service required should be performed by an authorized YAMAHA
Retailer or the appointed service representative.
IMPORTANT: The presentation or sale of this manual to any individual or firm does not constitute authorization, certification or
recognition of any applicable technical capabilities, or establish a principle-agent relationship of any form.
The data provided is believed to be accurate and applicable to the unit(s) indicated on the cover. The research, engineering, and service
departments of YAMAHA are continually striving to improve YAMAHA products. Modifications are, therefore, inevitable and
specifications are subject to change without notice or obligation to retrofit. Should any discrepancy appear to exist, please contact the
distributor's Service Division.
WARNING: Static discharges can destroy expensive components. Discharge any static electricity your body may have
accumulated by grounding yourself to the ground buss in the unit (heavy gauge black wires connect to this buss).
IMPORTANT: Turn the unit OFF during disassembly and part replacement. Recheck all work before you apply power to the unit.




s CONTENTS
TO SERVICE PERSONNEL . . . . . . . . . . . . . . . . . . . . 2 BLOCK DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
SPECIFICATIONS / . . . . . . . . . . . . . . . . . . . .3 PRINTED CIRCUIT BOARD . . . . . . . . . . . . . . . . . . . 20
FRONT PANELS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 SCHEMATIC DIAGRAM . . . . . . . . . . . . . . . . . . . 21­22
REAR PANELS . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4­5 PARTS LIST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23­31
INTERNAL VIEW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
DISASSEMBLY PROCEDURES / . . . . . . . .6
ADJUSTMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . 7­11
12­15
IC DATA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
DISPLAY DATA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
TX-497




2005 . All rights reserved.
100970 This manual is copyrighted by YAMAHA and may not be copied or
redistributed either in print or electronically without permission.
05.09
TX-497




AC LEAKAGE
TO SERVICE PERSONNEL WALL EQUIPMENT TESTER OR
Critical Components Information. OUTLET UNDER TEST EQUIVALENT
Components having special characteristics are marked
and must be replaced with parts having specifications
equal to those originally installed.

INSULATING
TABLE


WARNING: CHEMICAL CONTENT NOTICE!
The solder used in the production of this product contains LEAD. In addition, other electrical/electronic and /or plastic
(where applicable) components may also contain traces of chemicals found by the California Health and Welfare Agency
(and possibly other entities) to cause cancer and/or birth defects or other reproductive harm.

DO NOT PLACE SOLDER, ELECTRICAL/ELECTRONIC OR PLASTIC COMPONENTS IN YOUR MOUTH FOR ANY REA-
SON WHATSOEVER!

Avoid prolonged, unprotected contact between solder and your skin! When soldering, do not inhale solder fumes or expose
eyes to solder/flux vapor!

If you come in contact with solder or components located inside the enclosure of this product, wash your hands before
handling food.

About leadfree solder /
The P.C.B.s installed in this unit are soldered using the
following solder.
Side A / Side B /
TUNER P.C.B. -- Lead Free Solder /
OPERATION P.C.B. -- Lead Free Solder /

Side A SMT REFLOW Process



Solder Dip

Side B MI FLOW Process

Among some types of lead free solder currently available,
it is recommended to use one of the following types for the
repair work.
Sn + Ag + Cu (tin + silver + copper)
Sn + Cu (tin + copper)
Sn + Zn + Bi (tin + zinc + bismuth)


1. As the melting point temperature of the lead free solder
is about 30°C to 40°C (50°F to 70°F) higher than that of
the lead solder, be sure to use a soldering iron suitable
to each solder.
2. If lead solder must be used, be sure to remove lead free
solder from each terminal section of the parts to be
replaced and from the area around it completely before
soldering, or make sure that the lead-free solder and
lead solder melt together fully.
TX-497




2
TX-497




SPECIFICATIONS

FM SECTION Spurious Response Ratio
Tuning Range B, G, E models ..................................................... 50 dB
U, C models ..................................... 87.5 to 107.9 MHz Harmanic Distortion
R, T, A, B, G, E, L models ............ 87.50 to 108.00 MHz B, G, E models ..................................................... 0.3 %
J model .............................................. 76.0 to 90.0 MHz AUDIO SECTION
50dB Quieting Sensitivity (IHF) Output Level / Impedance
U, C, R, T,A, L, J models
Mono ................................................. 1.55 µV(15.1 dBf) (Fixed)
Stereo (1 kHz 100% MOD) 21 µV(37.7 dBf) U, C, R, T, A, L, J models
FM 100 % MOD 1 kHz ................... 900 mV/2.2 k-ohms
Usable Sensitivity (DIN) MW/AM/LW 30 % MOD 1 kHz ........150 mV/2.2 k-ohms
B, G, E models B, G, E models
Mono (S/N 26 dB) ............................................... 0.9 µV FM 100 % MOD 1 kHz ................... 500 mV/2.2 k-ohms
Stereo (S/N 46 dB) .............................................. 24 µV MW/LW 30 % MOD 1 kHz .............. 200 mV/2.2 k-ohms
Image Response Ratio GENERAL
U, C, R, T, J models ............................................. 40 dB
A, B, G, E, L models ............................................ 80 dB Power Supply
U, C models ........................................... AC120V, 60Hz
IF Response Ratio .................................. 70 dB R, L models ....... AC110 to 120V, 220 to 240V, 50/60Hz
Spurious Response Ratio T model .................................................. AC220V, 50Hz
U, C, R, T, J models ............................................. 60 dB A model .................................................. AC240V, 50Hz
A, B, G, E, L models ............................................ 70 dB B, G, E models ....................................... AC230V, 50Hz
Alternate Channel Selectivity J model ............................................. AC100V, 50/60Hz
U, C, R, T, J models ............................................. 85 dB Power Consumption ................................. 7 W
A, B, G, E, L models Dimensions (W x H x D) ........... 435 x 86 x 271mm
Selectivity (two signals) 40 kHz Dev. ±300 kHz ... 70 dB
Weight ........................................................... 3.2 kg
Signal to Noise Ratio (DIN-Weighted 40 kHz)
U, C, R, T, J models Finish
Mono .................................................................... 82 dB Gold color ................................................ T, L, J models
Stereo .................................................................. 76 dB Black color ...................... U, C, R, A, B, G, L, E models
A, B, G, E, L models Titanium color ............................... R, B, G, L, E models
Mono .................................................................... 75 dB Accessories
Stereo .................................................................. 70 dB Indoor FM Antenna x 1
Harmonic Distortion (1 kHz) AM Loop Antenna x 1
Mono .................................................................... 0.1 % Antenna Adapter x 1 (U, C models)
Stereo (B, G: 40 kHz Dev.) ................................... 0.2 % 75-ohm/300-ohm antenna adapter x 1 (B model)
Audio Pin Cable
Stereo Separation (1 kHz)
* Specifications subject to change without notice.
B, G: 40 kHz Dev. ................................................ 50 dB
Frequency Response
30 Hz to 13 kHz .............................................. 0±0.5 dB · DIMENSIONS
MW SECTION
13.4 (1/2")
Tuning Range
U, C, R models .................................... 530 to 1710 kHz
T, A, B, G, E, L, J models .................... 531 to 1611 kHz
Usable Sensitivity ............................ 200 µV/m
Selectivity .................................................. 32 dB (10-11/16")
(10-1/8")
256.6

271

Signal to Noise Ratio ...................... 50 dB
Image Response Ratio ................ 40 dB
Spurious Response Ratio ....... 50 dB
Harmanic Distortion ..................................... 0.3
LW SECTION
Tuning Range
(5/8") (2-3/4")

(3-3/8")




B, G, E models ...................................... 153 to 288 kHz
70

86




Usable Sensitivity
B, G, E models .............................................. 400 µV/m 435
Selectivity
16




(17-1/18")
B, G, E models .................................................... 32 dB
Signal to Noise Ratio
B, G, E models ..................................................... 50 dB
Image Response Ratio
B, G, E models ..................................................... 40 dB
TX-497




3
TX-497




FRONT PANELS
U, C, R, T, A, L, J models




B, G, E models




REAR PANELS
U, C models




R, L models
TX-497




4
TX-497




T model




A model




B, G, E models




J model




TX-497




5
TX-497




INTERNAL VIEW

Tuner P. C. B
Front-end pack
Operation P. C. B. (2)
Operation P. C. B. (3)
Operation P. C. B. (1)
Operation P. C. B. (4) (R, L models)




DISASSEMBLY PROCEDURES /
(Remove parts in the order as numbered.)
1. Removal of Top Cover
a. Remove 4 screws ( ) and 2 screws ( ). (Fig. 1.)
b. Slide the Top Cover rearward to remove it. (Fig. 1.)

2. Removal of Front Panel Unit
a. Disconnect the connectors (CB3 and CB4). (Fig. 1.)
b. Remove 3 screws ( ). (Fig. 1.)
. Screws ( ) are identified with arrow marks ( ).
c. Remove 2 screws ( ). (Fig. 1.)
d. Unhook at 2 place ( ). (Fig. 1.)
e. Remove the Front Panel Unit. (Fig. 1.)




t


r



e
t
r
TX-497




6
TX-497




ADJUSTMENTS Pressing the P1 key will cause operation to start from (1).
Pressing any other key will cause the mode to return to the
1. Before Adjustment
NORMAL mode.
(1)With the power turned on, wait for 5 minutes before
starting adjustment so that operation becomes stable.
(2)Adjust the OSC coil and IFT with insulated screwdriver. U, C models
(3)Set the TUNING MODE to AUTO. Preset P1 P2 P3 P4 P5 P6 P7 P8
(4)Decibel abbreviations
dBµ : Decibels above or below 1µV A, C, E 87.5 90.1 95.1 98.1 107.9 88.1 106.1 107.9
Example : B, D 630 1080 1440 530 1710 900 1350 1400
0dBµ = 1 µv, 60dBµ = 1 mV
X dBµ = (X + 11.2) dBf A, L, R models
When substituting 60 for X, Preset P1 P2 P3 P4 P5 P6 P7 P8
60 dBµ = 72.2 dBf
A, C, E 87.50 90.10 95.10 98.10 108.00 88.10 106.10 108.00

2. Measuring instrument abbreviations B, D 630 1080 1440 531 1611 900 1350 1404
FM SG : FM signal generator
B, G, E models
SSG : Stereo signal generator
AM SG : AM signal generator Preset P1 P2 P3 P4 P5 P6 P7 P8
DIST. M : Distortion meter A, E 87.50 90.10 95.10 98.10 108.00 88.10 106.10 108.00
FC : Frequency counter
B, D 630 1080 1440 531 1711 900 1350 1400
ACVM : AC voltage meter
DCVM : DC voltage meter C 153 171 225 270 288 180 207 252
RDS SG : RDS signal generator

1) Discriminator balance adjustment
Check that the voltage obtained across each test point
FM TP1
and ground on the tuner circuit is as follows. ANT
FM FM Tuner




R51
dummy GND DCVM
Test points Rating or Standard SG antenna P. C. B.

+5 V terminal +5.6 ±0.5 V TP2

-VP terminal -23.0 ±1.0 V oscillator


CAUTION : 2) Monaural distortion adjustment
Before setting to the TEST mode, write down the user
FM L
preset memory content in the table as shown below. (This ANT
FM Oscilloscope
is because setting to the TEST mode will cause the FM Tuner R
dummy GND
memory content to be the factory preset memory content, SG antenna P. C. B. OUT
PUT ACVM
i.e. all the user preset memory content will be erased.)

oscillator DIST. M
Preset keys P1 P2 P3 P4 P5 P6 P7 P8
A 3) Stereo distortion adjustment
B FM L
ANT Oscilloscope
C FM R
FM Tuner
dummy GND
D SG antenna P. C. B. OUT YLF-15
PUT (LPF) ACVM
E
SSG DIST. M

Turn on the POWER switch while pressing the A/B/C/D/
4) Sensitivity verification
E and FM/AM(FM/MW/LW) keys simultaneously, and
the unit enters the TEST mode for the display check. FM L
ANT Oscilloscope
After this, repeat (1) to (4). FM R
FM Tuner
dummy GND
SG antenna P. C. B. OUT
(1)All the segments on the display light up. PUT ACVM
(2)The model name, TX-497 is displayed.
TX-497




(3)The place of destination is displayed. DIST. M
(4)The µCOM-version is displayed.
7
TX-497




TEST POINTS





Reception Adjusted
Step Adjustment item Signal (ANT IN) Test point Rating
frequency point

Rough adjustment of FM SG: Preset L8 TP1, TP2 DC 0 V ±100mV
discriminator balance. 98.1 MHz 70 dBµ A-4: 98.1 MHz (right side) (both end at tuning point.
1
Modulation : 100 % of R51)
Monaural : 1 kHz

Rough adjustment of Same as Step 1. Same as Step 1. L8 OUTPUT Minimize distortion.
2
monaural distortion. (left side)

Fine adjustment of Same as Step 1. Same as Step 1. L8 TP1, TP2 DC 0 V ±50mV
3
discriminator balance. (right side)

Fine adjustment of Same as Step 1. Same as Step 1. L8 OUTPUT Minimize distortion.
4
monaural distortion. (left side) (to less than 0.7%)

Verification of Same as Step 1. Same as Step 1. TP1, TP2 DC 0 V ±50mV
5
discriminator balance.

Adjustment of frontend FM SG: Same as Step 1. Frontend TP3, GND Adjust so that the
IFT. 98.1 MHz 30 dBµ IFT DC voltage is
Modulation : 100 % maximum.
Monaural : 1 kHz CAUTION:
6 If IFT core is turned
excessively, the
sensitivity reduces.
(Maximum ±90°)

Adjustment of stereo FM SG: Same as Step 1. VR1, VR2 OUTPUT Minimize distortion.
distortion. 98.1 MHz 70 dBµ Tuning mode is
7
TX-497




Modulation : 100 % AUTO.
Stereo L or R : 1 kHz

8
TX-497




Reception Adjusted
Ste Adjustment item Signal (ANT IN) Test point Rating
frequency point

Verification of monaural FM SG: Same as Step 1. OUTPUT Minimize distortion.
distortion. 98.1 MHz 70 dBµ (to less than 0.7%)
8
Modulation : 100 %
Monaural : 1 kHz

Verification of stereo FM SG: Same as Step 1. OUTPUT Minimize distortion.
distortion. 98.1 MHz 70 dBµ (to less than 1.4%)
9
Modulation : 100 % Tuning mode is
Stereo L or R : 1 kHz AUTO.

Verification of FM SG: A-6: 88.1 MHz S/N should be 30 dB
sensitivity. 88.1/98.1/106.1 MHz A-4: 98.1 MHz at each frequency of
Modulation : 100 % A-7: 106.1 MHz 88.1 MHz, 98.1 MHz
10 Monaural : 1 kHz and 106.1 MHz.
Make sure that the
voltage at the ANT
terminal is 3 dBµ (7
dBµ at A, B, G, E
models) or less.

Adjustment of FM SG: Preset VR4 OUTPUT To more than 35 dB.
11 separation. 98.1 MHz 70 dBµ A-4: 98.1 MHz Tuning mode is
Modulation : 100 % AUTO.
Stereo L or R : 1 kHz

Adjustment of the signal FM SG: Preset VR3 Signal Adjust so that the
meter. 98.1 MHz 45 dBµ A-4: 98.1 MHz meter signal meter is
12
Modulation : 30 % maximum at rating
Monaural : 1 kHz level.

Verification of the signal ANT input minimum. Make sure that the
13 meter to turn off. signal meter is
turned off.

Verification of AUTO FM SG: Preset Tuning Automatic reception
TUNING. 98.1 MHz 23 dBµ A-4: 98.1 MHz buttons should be available
Modulation : 30 % when the tuning UP
Stereo L or R : 1 kHz or DOWN key is
pressed.
14
Stereo indicator is
turned on.
Audio muting should
be applied during
tuning.

Verification of AUTO PS RDS SG: Preset Make sure that the
(program service name) Modulation : 1.6 % A-4: 98.1 MHz display automatically
[B, G, E models only] (1.2 kHz) turns to the PS
15 FM SG: mode and PS
98.1 MHz 40 dBµ indicator turns on
Modulation : 100 % when the signal is
Monaural : 1 kHz tuned again.
TX-497




9
TX-497




AM loop antenna

To be adjusted after FM section adjustment.
Use the specified dummy anetenna for loop antenna.



AM dummy antenna

AM ANT

AM
SG
GND



Reception Adjusted
Step Adjustment item Signal (ANT IN) Test point Rating
frequency point

Adjustment of AM SG: Preset L5 OUTPUT Maximize detected
sensitivity. 630 kHz 50 dBµ, B-1: 630 kHz signal output.
1
1 kHz,
30% modulation

Verification of AM SG: Preset To be less than 54
sensitivity. 630 kHz/1080 kHz/ B-1: 630 kHz dBµ.
2 1440 kHz 50 dBµ, B-2: 1080 kHz
1 kHz, B-3: 1440 kHz
30% modulation

Verification of the signal AM SG: Preset Make sure that the
meter. 1080 kHz 90 dBµ, B-2: 1080 kHz signal meter is
ANT input 90 dBµ turned on.
3
ANT input -10 dBµ or Make sure that the
less signal meter is
turned off.

Verification of auto AM SG: Preset Tuning Automatic reception
tuning. 1080 kHz 60 dBµ, B-2: 1080 kHz button should be available
1 kHz, when the tuning UP
30% modulation or DOWN key is
4
pressed.
Audio muting should
be applied during
tuning.
TX-497




10
TX-497




AM loop antenna
To be adjusted after MW section adjustment.
Use the specified dummy anetenna for loop antenna.




AM dummy antenna

AM ANT

AM
SG
GND




Reception Adjusted
Step Adjustment item Signal (ANT IN) Test point Rating
frequency point

Verification of AM SG: Preset OUTPUT To be less than 66
sensitivity. 171 kHz/225 kHz/270 C-2: 171 kHz dBµ.
1
kHz 90 dBµ, C-3: 225 kHz
1 kHz, C-4: 270 kHz
30% modulation

Verification of the signal AM SG: Preset Make sure that the
meter. 225 kHz 90 dBµ, B-2: 225 kHz signal meter is
ANT input 90 dBµ turned on.
2
ANT input -10 dBµ or Make sure that the
less signal meter is
turned off.

Verification of auto AM SG: Preset Tuning Automatic reception
tuning. 225 kHz 60 dBµ, B-2: 225 kHz button should be available
1 kHz, when the tuning UP
3 30% modulation or DOWN key is
pressed.
Audio muting should
be applied during
tuning.




TX-497




11
TX-497 TX-497




12
TX-497




TX-497




13
TX-497 TX-497




14
TX-497




TX-497




15
TX-497




IC DATA

IC501 : LC866420A
8-bit Microprocessor




No. Port I/O Name Function No. Port I/O Name Function
1 P17/PWM0 O /MMUTE Main mute 41 VDD2 I VDD +5V
2 P30 I ROT1 Rotary encoder input 42 VP I VDDVPP --24V
3 P31 I ROT0 This input available for ROTSW=H 43 S16/PC0 O P1 FL segment
4 P32 I MODEL Model 0 44 S17/PC1 O P2 FL segment
5 P33 I ROTSW Rotary encoder yes(H) or no(L) 45 S18/PC2 O P3 FL segment
6 P70/INT0 I 46 S19/PC3 O P4 FL segment
7 /RES I /RESET Reset 47 S20/PC4 O P5 FL segment
8 /P74/XT1 I 48 S21/PC5 O P6 FL segment
9 P75/XT2 I 49 S22/PC6 O P7 FL segment
10 VSS1 I GND GND 50 S23/PC7 O P8 FL segment
11 CF1 CF 6MHz 51 S24/PD0 O P9 FL segment
12 CF2 CF 6MHz 52 S25/PD1 O P10 FL segment
13 VDD1 I VDD +5V 53 S26/PD2 O P11 FL segment
14 P80/AN0 ADI KEYIN1 AD key input 54 S27/PD3 O P12 FL segment
15 P81/AN1 ADI KEYIN2 AD key input 55 S28/PD4 O P13 FL segment
16 P82/AN3 ADI KEYIN3 AD key input 56 S29/PD5 O P14 FL segment
17 P83/AN3 ADI METER Signal level input 57 S30/PD6 O P15 FL segment
18 P84/AN4 I 58 S31/PD7 O
19 P85/AN5 I 59 S32/PE0 I/O
20 P86/AN6 I 60 S33/PE1 I/O
21 P87/AN7 ADI VER Version input 61 S34/PE2 I/O
22 P71/INT1 I 62 S35/PE3 I/O
23 P72/INT2 I /POWERDOWN Power down detect 63 S36/PE4 I/O
24 P73/INT3 I REM REM input 64 S37/PE5 I/O
25 S0/T0 O 13G FL segment 65 P00 O
26 S1/T1 O 12G FL segment 66 P01 O
27 S2/T2 O 11G FL segment 67 P02 O
28 S3/T3 O 10G FL segment 68 P03 O
29 S4/T4 O 9G FL segment 69 P04 O /TMUTE Tuner mute
30 S5/T5 O 8G FL segment 70 P05 O
31 S6/T6 O 7G FL segment 71 P06 O RSYN Block Synchronous Detect Output
32 S7/T7 O 6G FL segment 72 P07 O RCE Chip Enable
33 S8/T8 O 5G FL segment 73 VSS2 I GND GND
34 S9/T9 O 4G FL segment 74 P10/S00 O RDI Data Input
35 S10/T10 O 3G FL segment 75 P11/SI0 SIN RDO Data Output
36 S11/T11 O 2G FL segment 76 P12/SCK0 SCL RCL Clock Input
37 S12/T12 O 1G FL segment 77 P13/SO1 I PLLDAT-i n Data input from PLL
38 S13/T13 78 P14/SI1 O PLLDAT-ou t Data output for PLL
39 S14/T14 79 P15/SCK1 O PLL-CLK PLL clock
40 S15/T15 80 P16/BUZ O PLLCE PLLCE


KEY INPUT
Key Input 1 2 3 4 5 6 7
Resistance () 0k 1.8k 2.7k 3.9k 6.8k 13k 39k
Extent of AD 00H~15H 16H~3DH 3EH~64H 65H~8AH 8BH~B0H B1H~D3H D4H~F0H
Extent of Voltage (V) 0.00~0.41 0.41~1.19 1.19~1.95 1.95~2.70 2.70~3.44 3.44~4.12 4.12~4.69
TX-497




Pin No.14 KEYIN1 P3 P4 P5 P6 P7 P8
Pin No.15 KEYIN2 MODE EDIT (KMODE) MEMORY PAGE P1 P2
Pin No.16 KEYIN3 FREQ/TEXT PTY SEEK MODE PTY SEEK START EON FM/AM (MW/LW) TUNING DOWN TUNING UP

16
TX-497


DISPLAY DATA (13-BT-152GK)




PIN CONNECTION
PIN NO. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

CONNECTION F1 NP NP P15 P14 P13 P12 P11 P10 P9 P8 P7 P6 P5 P4 P3 P2 P1


PIN NO. 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35

CONNECTION NC 1G 2G 3G 4G 5G 6G 7G 8G 9G 10G 11G 12G 13G NP NP F2

NOTE:
1) F1, F2 ................. Filament
2) NP ....................... No pin
3) NC ....................... No connection
4) DL ....................... Datum line
5) 1G~13G .............. Grid


ANODE CONNECTION

13G 12G 11G 10G 9G 8G 7G 6G 5G 4G 3G 2G 1G
P1 a a a a a a a a a a a
P2 b b b b b b b b b b b
P3 c c c c c c c c c c c
P4 d d d d d d d d d d d
P5 e e e e e e e e e e e
P6 f f f f f f f f f f f
P7 g g g g g g g g g g g
P8 h h h h h h h h h h h
P9 j j j j j j j j j j j
P10 k k k k k k k k k k k
P11 m m m m m m m m m m m
P12 n n n n n n n n n n n
P13 p p p p p p p p p p p
P14 r r r r r r r r r r r
P15 t t t t t t t t t t t


17
A B C D E F G H

TX-497


s BLOCK DIAGRAM
1


L7
FM DET MPX IC
FM FRONT END AM/FM IF IC COIL
IC3 : LA3401 LPF
PK1
IC2 : LA1266 L12
RF AMP L2 Q2, 5 L3 Q3, 4 Q10 L4 Q13 FM IF AMP Q16 L10
MIXER L ch
MUTE
FM 75 FM/AM SW
MUTING DECODER
Q19,20
GND VR1, 2 QUADRATURE
DET Q22,23 R ch
LEVEL DET
AM DE-EMPHASIS L13
OSC
IF PLL
BUFFER BUFFER
XL3
2 CONTROL
IF
BUFFER ST IND. MUTE
L9
CERAMIC
Q15 FILTER
L5 AM
DET
AM COIL PACK PK2
RF AMP MIXER
ANT A GC
COIL

OSC OSC S . M E TE R LED
COIL DRIVER


3 PLL IC1 : LC72130
-COM RDS B, G, E models
10
IC401
LC72720
1 REFERENCE PHASE DETECTOR 19
DIVIDER CHARGE PUMP
24 20 , ~
CMOS
18
15 1/2 SWALLOW COUNTER UNLOCK
CONTROL &1 ~ &2
1/16, 1/17 4bits DETECTOR 17 TUNING
&4 ~ &6
21 Q502 LSI
14 12bits PROGRAMMABLE RESET
DIVIDER 22
IC501
3
LC866420A
4 C2B DATA SHIFT REGISTER LATCH UNIVERSAL 12 Q501 V501
I/F COUNTER P O WE R
5 ON 8 bit CPU
4 6