Yamaha BD-940, Service Manual, Page: 48 / 60

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8
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B C D E F G H I J K L M N
BD-940
48
POWER
★
All voltages are measured with a 10MΩ/V DC electronic voltmeter.
★
Components having special characteristics are marked
⚠
and must be replaced
with parts having specifications equal to those originally installed.
★
Schematic diagram is subject to change without notice.
IC3
IC2
CB3
IC1
IC4
36.2
0
12.2
0
-12.2 0
36.2
12.2
12.2
12.2
0
0
0
0
-12.5
0
AC
14.8
AC
7.6
AC
4.4
Primary side ground
2.4
0
7.4
0
(0.9)
(14.9)
-12.5
14.3
14.3
14.3
12.2
(0)
(3.3)
7.4
8.4
(14.9)
(1.1)
(14.9)
(9.3)
(4.0)
(0)
(0)
(0)
(0)
(319.5)
(0.3)
(319.5)
(111.6)
(111.4)
(0.3)
(0.2)
(14.9)
(0)
(1.1)
(1.1)
(0)
(1.1)
(5.0)
(0.2)
(0)
(2.4)
(0.4)
(1.2)
(1.1)
(319.2)
(319.2)
(448.2)
(448.2)
(319.5)
0
IC1 : L6566BTR
Multi mode controller for SMPS
MODE SELECTION
and
TURN-ON LOGIC
R
PWM
Q
S
DISABLE
VOLTAGE
REGULATOR
and
ADAPTIVE UVLO
TIME
OUT
UVLO_SHF
UVLO
Internal supply
Vcc
Reference
voltages
Vcc VIn
OCP2
4.5V
Q
6.4V
OVPL
1.5 V
BURST-MODE 5.7V
OVP
UVLO
AC_FAIL
ZERO CURRENT
DETECTOR
50 mV
100 mV
0.450V
0.485V
TIME
OUT OVPL
14V
IC_LATCH
OFF2
400 uA
OFF2
OVP
-
-
-
+
+
OCP
- + - +
+
+
-
-
+
-
+
-
+
OVERVOLTAGE
PROTECTION
LATCH
SOFT-START
and
FAULT MNGT
LOW CLAMP
and DISABLE
LEB
OSCILATOR
1
10 14 9 15
7
4
5
6
13
12
11
16
HV
VREF SS AOMP VFF
CS
GD
8
3
GIS
GND
Vcc
FMOD
OSC
MODE/SC
ZCD
AC_OK
3 V
15 uA
DRIVER
15 uA
7.7V
1 mA
Hiccup-mode
OCP logic
LINE VOLTAGE
FEEDFORWARD
IC4 : NJM431U
Adjustable precision shunt regulator
ANODE REFERENCE CATHODE
1 2 3
AC IN
POWER
TRANSFORMER
to MAIN (1)_CB203
Page 45 A3