Yamaha GX-900 Service Manual page 78

A B
GX-900
SCHEMATIC DIAGRAM (MAIN)
1
0
0
-12.7
-27.3
-26.8 -51.2
-12.1
2
REGULATOR
P86 L-2
12.5 23.3 12.4
P85 H-6 12.9
13.0
12.9
13.0
3
0
0
P87 K-6
POWER AMP
P87 K-4
4
MUTING
0
5
-6.0
0
0
-6.0
0
6
7
8
89
C D E
REGULATOR
-12.7
-23.8
23.3
51.0
23.3
50.9
10.3
0
-0.1
0
0
-0.1
0
0
0
0
0
-0.1
50.8
0 0
-0.1 0
-10.8
-23.8
F G
51.0
-51.2
POWER
PROTECTION
SUPPLY
4.8
12.4 -23.8
23.3
0
11.7
4.8
0
12.4
0 0
0.6
0
12.3 0
-0.9
-22.9
-23.1
-23.8
H I
IC201 : STK496-420Y
2 Channel AF Power Amp
17
18
TR3
19
20
SUB
POWER SUPPLY
9.2
9.2
0
0.7
0 0
P87 K-5
* All voltage are measured with a 10MΩ/V DC electric volt meter.
* Components having special characteristics are marked Z and
* Schematic diagram is subject to change without notice.
J K L
R31 1
TR31
3
D6
R4
R14
TR1 TR2 TR14 TR13 COMPARATOR
5
D7
TR21 D35
TR6 TR9
D33
TR11 TR23
C2 C4
R2 C1
C3 R12
D31
4
R19 TR20
R9
TR4 R5 TR16 TR15
R15
2
TR8 TR12 TR24
SUB
R6 R16 D32
7
TR10
TR22 D34
TR7 TR19
TR32 D36 6
TR5 TR17
D1
R7 R17
COMPARATOR
R3
R8 R18
R13
R32
R51
8
12 13 16 10 14 15 11 21 22 9
must be replaced with parts having specifications equal to those
originally installed.