Yamaha YST-SW800, Service Manual, Page: 15 / 26

A B C D E F G H
1
2
3
4
5
6
I J K
7
8
YST-SW800
■
SCHEMATIC DIAGRAM
V
O1
2
–Vm
1
3
+Vm
1
4
V
EE
5
+Vm
2
6
–Vm
2
7
V
O2
8
V
CC
9
V
CC
1
1
– + – +
2
IC1, 2, 4, 6, 7 :
µ
PC4570HA
Dual OP-Amp
IC5 : M51848L
CR Timer
* All voltage are measured with a 10M
Ω
/V DC electric volt meter.
* Components having special characteristics are marked
Z
and
must be replaced with parts having specifications equal to those
originally installed.
* Schematic diagram is subject to change without notice.
2SK304 (E)
NJM4558L
µ
PC1237HA
M51848L
µ
PC4570HA
1
9
1SS133
S2L20U
EL02Z
1SR139-400
MTZJ2.0B
MTZJ12.0B
MTZJ24.0B
Anode
Cathode
B
C
E
2SA970 (GR, BL)
2SA1015 (O, Y)
2SA1689 (E, F)
2SC1815 (Y, GR)
2SC2240 (GR, BL)
2SC4449 (E, F)
2SC2878 (A, B)
D
G
S
PIN CONNECTION DIAGRAM OF TRANSISTORS, DIODES AND ICS.
14
L.P.F.
L.P.F.
L.P.F.
H.P.F.
B.P.F.
LIMITER
PRE DRIVE
POWER DRIVE
PROTECTION
POWER SUPPLY
A.N.I.C
AUTO POWER ON/OFF
CIRCUIT
0
0
0
11.8
8.6
-4.4
11.8
7.9
8.5
0
0
4.1
0
0
0.7
0
0
0
-12.0
0
0
0
-12.0
0
0
0
11.8
0
0
1.8
0
0
0.6
7.8
7.2
0
0
0
-12.0
0
0
0
11.8
0
3.9
7.8
0
3.9
6.9
0
0
7.5
0
1.4 6.5 7.8 5.2 7.7 7.7 7.8
6.5
5.9
0
0
0
11.8
0
0
-0.3
-0.3
-12.0
-0.4
0
0
0
-12.0
0
0
0
0
11.8
0
0
-1.5
0 0
0
0.2 -0.1
-0.3 0.2
-12.0
11.8
0
0 0
0
0 0
-112
-111
-111
-111
-112
-111
-111
-110
-3.4
-111
-111
-111
0.2 0.2
0.7
0.7
110
112
112
111
110 110
111
3.4
-2.6
-3.4
3.4
3.4
2.9
6.0
112
111
5.5
2.9
5.5
2.3
2.3
0.1
2.3
4.7
2.3
111
111
111
110
110
111
111
111
4.7
4.7
111
0
0
111
0.1
0.1
0
-4.3
-4.9
-2.0
-0.1
-2.1
-2.1
-111
-5.2
-2.7
-2.7
-5.8
-111
-3.2
-111
-110
-110
-111
-111
-111
-110
-111
-4.3
-4.3
-4.3
-111
3.1 2.1 0.8
0
2.0
0 0
6.6
6.0
0.8
11.8
6.0
IDLING CURRENT ADJ.
DC 50mV to 250mV
A
B
0.7
-110
0
0
0.1
2.9
111
5.1
5.1
5.1
111
4.7
4.7
110
0.1
110
4.7
4.7
4.7
4.7
111
4.7
4.7
4.7
0
111
-2.7
-4.9
-5.2
-4.9
-110 -110
-4.3
-4.3
-4.3
-4.3
-4.3
0
0.1
-4.3
0 -4.3
-111
112
-0.8
-1.5
-0.8 -1.5
112
-111
0
15.3
0
15.3
11.8
0
-12.0
-15.3
0
0
-15.3
0
CIRCUIT CHANGES BY MARKET.
X : NOT USED
RE
WH
B
CE
2SA1837
2SC4793
1
8
IC11 : NJM4558L
Dual OP-Amp
–
IN
1
2
+IN
1
3
–
V
CC
4
+IN
2
5
–
IN
2
6
OUT
2
7
+V
CC
8
OUT
1
1
–
+
–
+
IC3 :
µ
PC1237HA
Protector IC for Power Amplifier
1
2
5 3 4
7 8
6
Overload
detect
Mid-point
potential
detect
Flip flop
circuit
Vcc on
mute
AC OFF
detect
Latch / automatic
return select
Relay
drive
circuit
GND
Vcc
GND
6
4
1
2 3
TRIGGER
OUT
RESET
REFERENCE
VOL
T
AGE
THRESHOLD
DISCHARGE
VCC
7
8
+
–
FLIP-
FLOP
+
–
5
R R R
2SC1846S
E C
B
2SK237B
2SJ406 NJM78M12FA NJM79M12FA
1: OUTPUT
2: COMMON
3: INPUT
3 2
1
1:COMMON
2:INPUT
3:OUTPUT
3 2
1
G
DS
FMU-12R
FMU-34R FMU-12S
FMU-34S
Point A (Cathode of D27)
V : 50V/div H : 2 msec/div
DC range 1 : 1 probe
0V
Point B (Anode of D24)
V : 50V/div H : 2 msec/div
DC range 1 : 1 probe
0V
1
3
2
1:Cathode
2:Anode
3:Cathode
3
2
1
1
3
2
1:Anode
2:Cathode
3:Anode
3
2
1
SAME PAGE
D-3
SAME P
A
GE
E-7
P15
I-2
P15
I-4
P15
I-5