Sherwood RX-772 User manual

RX-772
STEREO RECEIVER
- SPECIFICATION - TROUBLESHOOTING
- BLOCK DIAGRAM - MECHANICAL PARTS LIST
- WIRING DIAGRAM - EXPLODED VIEW
- LEVEL DIAGRAM - ELECTRICAL PARTS LIST
- CIRCUIT DESCRIPTION - SCHEMATIC DIAGRAMS
- TUNER ALIGNMENT
◑ CONTENTS ◑
SERVICE MANUAL

Measuring methods are based on IHF and IEC standard 268-3
Measurements conditions, unless otherwise noted :
Output resistive load = (8) ohms / Both channel driven
Tone(Bass, Treble), Balance, EQ control : Center Position , Other SW's : OFF
Nominal input level : 5mV for MM, 0.5mV for MC, 220mV for general purpose inputs
Power figures should be kept minimum 10min. between 15 and 35 ℃
Terminator : 100ohm for MC, 1kohm for MM and general purpose inputs
Filter : IHF-A filter R/O = Rated Output
Power supply : 230V / 50Hz(RDS), 220V / 60Hz(K)
●
FRONT AMP SECTION ( 2-CH STEREO RECEIVER )
DESCRIPTION INPUT FREQ. REMARK UNIT NOMINAL L/R LIMIT L/R
INPUT SENSITIVITY EXT 1kHz mV 200±30 200±50
@ 1kHz , 47kΩ(RDS) MIC 1kHz mV - -
(K) MIC 1kHz mV 3±0.5 3±1
CHANNEL BALANCE EXT 1kHz R/O TO -40dB dB ±0.5 ±2
RESIDUAL NOISE, IHF-A FILTER 1kHz VOL min. ≤0.2 ≤0.5
AT INPUT SHORTED 1kHz VOL max. mV ≤1.5 ≤2
TOTAL HARMONIC DISTORTION 20Hz % ≤0.02 ≤0.08
1kHz % ≤0.02 ≤0.08
20kHz % ≤0.05 ≤0.1
CONTINUOUS AVERAGE POWER 20Hz W 103 100
at (0.08)% THD 1kHz W 103 100
20kHz W 103 100
S/N RATIO, IHF-A FILTER EXT 1kHz R/O dB ≥95 ≥92
CHANNEL SEPARATION 1kHz dB ≥65 ≥55
AT INPUT SHORTED 10kHz dB ≥45 ≥40
FUNCTION CROSSTALK AUX→CD 1 kHz dB 75 70
AT INPUT SHORTED CD→AUX 1 kHz dB 75 70
FREQUENCY RESPONSE (-3dB)
1kHz Ref
15~90Hz~kHzEXT 10~100
R/O
R/O
8
1W
EXT
9
6
7
R/O TO -3dB
5
EXT 8ohms
3
EXT
4
EXT
SPECIFICATION
No.
1
2

DESCRIPTION INPUT FREQ. REMARK UNIT NOMINAL L/R LIMIT L/R
TONE CONTROL 100Hz dB ±10±1 ±10±3
10kHz dB ±10±1 ±10±3
IDLE CURRENT
NO INPUT LATER 10 MINUTE (RDS) INPUT SHORT mV 4.5±1 4.5±1.5
(K) INPUT SHORT mV 4.5±0.5 4.5±1
REC OUTPUT TAPE,VIDEO (RDS) 200±30 200±50
(K) 200±20 200±30
HEADPHONE OUTPUT
H/P = 64ohms
●PHONO SECTION
DESCRIPTION INPUT FREQ. REMARK UNIT NOMINAL L/R LIMIT L/R
INPUT SENSITIVITY PHONO 1kHz 150mVrms(REC OUT) mV 2.7±0.3 2.7±0.5
S/N RATIO INPUT SHORT
HF-A FILTER
RIAA DEVIATION (VOL MIN) 20Hz ~ dB ≤19.2±0.3 ≤19.2±1
20kHz dB ≤-19.6±0.3 ≤-19.6±1
MAX INPUT VOL MIN THD 0.1% PHONO 1kHz REC OUT ㎷rms ≥120 ≥100
THD IHF-A FILTER PHONO 1kHz 3Vrms(REC OUT) %≤0.002 ≤0.01
1kHzPHONO
REC OUTPHONO
≥75
80dB
150mVrms(REC OUT)
V 3±0.53±0.3
mV
EXT 1kHz R/O
1 kHz
VOL MIN
EXT 1W
12
13
No.
10
11
4
5
No.
3
1
2

Measuring methods in confirmity with IEC standard 315
Measurements condition FM : Radio frequency = 98.0MHz(RDS), 98.1MHz(K)
Audio frequency = 1kHz Reference level = 1mV on ( 75ohms ) Filter = B.P.F at STEREO
Deviation : MONO = ±75kHz, Stereo = ±67.5kHz±7.5kHz
Test Point : TP 1 = 90.0MHz, TP 2 = 98.0MHz, TP 3 = 106.0MHz(RDS)
Test Point : TP 1 = 90.1MHz, TP 2 = 98.1MHz, TP 3 = 106.1MHz(K)
Power supply : 230V / 50Hz(RDS), 220V / 60Hz(K)
●FM SECTION
No. UNIT NOMINAL L/R LIMIT L/R
1 TUNING RANGE LOW ~ HIGH MHz
STEP(RDS) AUTO/Man. kHz
(K) AUTO/Man. kHz
2 USABLE SENSITIVITY TP 1 dBµV ≤5≤12
S/N = 30dB TP 2 dBµV ≤5≤12
TP 3 dBµV ≤5≤12
3 AUTO STOP LEVEL dBµV 20±3 20+14/-10
4 S/N RATIO @1mV MONO dB ≥70 ≥65
IHF-A FILTER STEREO dB ≥65 ≥60
5 TOTAL HARMONIC DISTORTION MONO % ≤0.5 ≤1
STEREO % ≤0.8 ≤2
6 50dB QUIETING SENS. MONO dBµV ≤15 ≤25
STEREO dBµV ≤35 ≤45
7 CHANNEL SEPARATION 100Hz dB ≥35 ≥30
1kHz dB ≥35 ≥30
10kHz dB ≥30 ≥25
8 FREQUENCY RESPONSE AT ±3dB
1kHz=0dB 50㎲(RDS), 75㎲(K)
9 SPURIOUS RESPONSE dB ≥76 ≥60
10 IF REJECTION TP 1 dB ≥80 ≥70
11 IMAGE REJECTION TP 3 dB ≥46 ≥30
12 AM REJECTION RATIO AT AM 30% dB ≥60 ≥55
13 OUPUT LEVEL MONO TAPE REC OUT mV 600±150 600±180
100 / 100
Hz 40~14K 50~12.5K
TUNER SECTION
DESCRIPTION
87.5~108
50 / 50

●AM SECTION
Measuring methods in confirmity with IEC standard 315
Measurements condition AM - MW : Radio frequency = 1000/999kHz, Audio frequency = 400Hz
Reference level = 5mV/m,10mV/m on 50ohms Modulation = 30%
Test Point : MW TP1 = 603kHz, TP2 = 999kHz, TP3 = 1404kHz
No. UNIT NOMINAL L/R LIMIT L/R
1 TUNING COVER RANGE LOW ~ HIGH MW kHz
STEP AUTO/Man. kHz
2 USABLE SENSITIVITY TP 1 dBu/m ≤55 ≤65
S/N = 20dB TP 2 dBu/m ≤55 ≤65
TP 3 dBu/m ≤55 ≤65
3 S/N RATIO
(100dBu/m,30% MOD)
4 TOTAL HARMONIC DISTORTION
(74dBu/m,30% MOD)
5 OVER LOAD DISTORTION
(94dBu/m,80% MOD)
6 FREQUENCY RESPONSE at -6dB
(at 74dBu/m,400Hz)
7 SELECTIVITY 10kHz/9kHz TP 2 dB ≥23 ≥15
8 AGC FIGURE OF MERIT
(at 100dBu/m,400Hz)
9 IMAGE REJECTION TP 3 dB ≥30 ≥25
10 WHISTLE MODULATION 2IF=74dBu/m % ≤10 ≤15
3IF=94dBu/m % ≤10 ≤15
11 AUTO STOP LEVEL 999kHz dBu/m ≤46 ≤65
522kHz dBu/m ≤57 ≤75
1611kHz dBu/m ≤55 ≤70
12 TUNED LEVEL dBu/m ≤48 ≤65
13 OUTPUT LEVEL (74dBu/m,30% MOD) mV 200±50 200±70
≥40≥60
dBTP 2
TP 2 Hz 60~2.2K 100~2K
TP 2 % ≤3≤5
≤3
TP 2 dB ≥45
DESCRIPTION
TP 2 % ≤1.5
≥40
522~1611
9/9

UPD78F0536GK : IC201
1. Pin Description
64 63 62 61 60 59 58 57 56 55 54 53 52 51 50 49
1 48
2 47
3 46
4 45
5 44
6 43
7 42
8 41
9 40
10 39
11 38
12 37
13 36
14 35
15 34
16 33
17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32
VDD
POWER_DOWN
X1
VOL-UP
NC
NC
FLMD0
X2
SPK_B_RLY
SPK_A_RLY
CIRCUIT DESCRIPTION
EVDD
PROTECTION
ST/BY_RLY
REGC
VSS
EVSS
KEY1 TONE_DN
NC
FLT_CE RMC
PLL_DA
24C08_SCLK SET_OPTION STEP_OPTION VOL_DN FLT_RESET TONE_UP NC FUN_UP FUN_DN 24C08_SDA
HP_RLY
RESET
FUN_DATA
P32
FUN_CLK RDS_CLK
RDS_DATA
PLL_CE
PLL_DI
PLL_CLK
GND
AVREF
FLT-CLK
NC
FLT_DATA
TxD
RxD
STBY2
STBY1
RDS/FLT
DIGILINK
VOL_CLK
VOL_DATA
PLL_ST
PLL_TUNED
P31
FUN_ST
PLL_MUTE
MUTE
NC NC NC

2. Block Diagram