Yamaha Mx12.6 Service Manual

MX12/6
MX20/6
11
+30dB
+20dB
+10dB
0dB
–10dB
–20dB
–30dB
–40dB
–50dB
–60dB
STEREO [0dB]2dB]FECT [-6dB]EREO [-6dB]Max. Before Clip
AUX SEND [+4dB]
EFFECT SEND [+4dB]
AUX
EFFECT
Control MasterGROUP
Fader MasterMax. Before Clip
GROUP OUT [+4dB]
REC OUT [-10dBV]
ST
FaderMasterMONO Master 
ControlMax. Before Clip
ST OUT, MONO OUT [+4dB]
C-R/PHONESC-R/PHONES [+4dB@10kohms]
C-R/PHONES
[3mW@40ohms]
STEREO R
EFFECTSTEREO LGROUP4AUX1
AUX2 STEREO R
EFFECT STEREO L
GROUP4AUX1
AUX2
GROUP1 Fader
[0dB]
INV
INV
INV
INV...

MX12/6
MX20/6
12
WIRING
CN208
A ACN404
CN401 CN501
CN502
CN402CN403CN203
CN303
(
MX20/6 only)(
MX12/6 only)
CN
2/22/4
1/2
(
MX12/6)
to MAIN1/4 CN207
IN8-CN403
(
MX20/6)toMto IN
IN8MAIN
IN8
M DCJ
K 

MX12/6
MX20/6
13
A A
CN207
CN201CN202
2/2
1/4
CN204
CN304
CN305 CN105
CN302CN301
1/2
CN107
CN108
CN207to MAIN1/4 CN207(
MX12/6)
to IN8-CN403(
MX20/6)
CN106
to MAIN4/4 CN305
CN109 CN102CN104
CN103
CN101AC
POWER
SWITCH
POWER
TRANSFORMER
3/4
CN306
DCJK
MAIN DCJK
MAIN
4/4 MAIN 

MX12/6
MX20/6
14
CIRCUIT BOARD LAYOUT
2/2(
MX20/6 model only)2/2
2/2 2/4
(
MX20/6 model only)1/2
1/41/2
3/4
4/4 IN8 DCJK
DCJK MAIN
IN8
MAINDCJK
MAIN
MAIN 

MX12/6
MX20/6
15
DISASSEMBLY PROCEDURE
Fig.1 1. Panel Assembly
1-1. With the unit placed so that the rear panel faces
forward, remove the screws marked [30] and lift the
rear panel. The panel assembly can then be
removed. (Fig. 1)
[30]: Bind Head Tapping Screw-B  3.0 X 8 MFZN2BL (EP600190)  MX12/6: 18 screws  MX20/6: 19 screws
View A
[30] [30]Rear side
Rear side
[30] [30]
[30]
[30] [30]Top side
MX12/6
MX20/6Side view
[30] 

MX12/6
MX20/6
16
Fig.2
[P50]:Hexagonal Button-P 3 X 25 MFZNBL (V3289800)
[P60]:Bonding Tapping Screw-B 3.0 X 8 MFZN2BL (VN413300)
[P70]:Bind Head Tapping Screw-B 3.0 X 8 MFZN2BL (EP600190)
2. MAIN 1/4 Circuit Board
2-1.Remove the panel assembly. (See Procedure 1.)
2-2.Remove the twelve (12) screws marked [P50A], the
twenty-three (23) screws marked [P60A], each knob
and hexagonal nut. The MAIN 1/4 circuit board can
then be removed. (Fig. 2)
3. MAIN 4/4 Circuit Board
3-1.Remove the panel assembly. (See...

MX12/6
MX20/6
17
Fig.3
[B70]:Bind Head Tapping Screw-B 3.0 X 8 MFZN2BL (EP600190)
[B90]:Bind Head Tapping Screw-B 3.0 X 8 MFZN2BL (EP600190)
[B100]:Bind Head Tapping Screw-B 3.0 X 8 MFZN2BL (EP600190)
6. DCJK 1/2 Circuit Board
6-1.Remove the panel assembly. (See Procedure 1.)
6-2. Remove the nine (9) screws marked [B90] and pull off
the DCJK 1/2 circuit board from the PCB support. (Fig. 3)
7. Heat Sink
7-1.Remove the panel assembly. (See Procedure 1.)
7-2. Remove the five (5) screws marked [B70]. The...

MX12/6
MX20/6
18
LSI PIN DESCRIPTION
PINNo.NAME I/O FUNCTION PIN
No.NAME I/O FUNCTION
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
5253
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100 ED2
ED3
ED4
ED5
ED6
ED7
VSS
VDD
CLKM0
CLKM1
TMS
TDI
TCK
CLKIN
VSS
VDD
CLKO
EA12/ED8
EA13/ED9
EA14/ED10
EA15/ED11
VSS
VDD
EA16/ED12...

MX12/6
MX20/6
19
PIN
No.NAME I/O FUNCTION PIN
No.NAME I/O FUNCTION
1
2
3
4
5
6
7
8
9
10
11
12
13
1415
16
17
18
19
20
21
22
23
24
25
26
27
28 VINL
Vcc1
AGND1
VREFL
VREFR
VINR
CINPR
CINNR
CINNL
CINPL
VCOM
VOUTR
AGND2
Vcc2VOUTL
LRCIN
BCKIN
DIN
DOUT
XTI
XTO
CLKIO
VDD
DGND
FMT2
FMT1
FMT0
RSTB I
I
OO
I
I
I
O
I
O
I/O
I
I
I
I
PCM3001E (XY282A00)
ADAMAIN: ICM04
ADC Analog Input, Lch
ADC Analog Power Supply
ADC Analog GND
ADC Reference decouple, Lch
ADC Reference Decouple, Rch
ADC Analog Input, Rch
ADC...

MX12/6
MX20/6
20
IC BLOCK DIAGRAM
NJM4580L (XF195A00)
Operational AmplifierTC74HCU04AP (IG142200)
Inverter
M5229P (XG203A00)
7-SEG. GRAPHICBA682A (XS046A00)
LED Level Meter
1A2345678
IN V+IN
OUT
AAA+V IN+IN
OUT
BBB
+B+
1A2345678
IN V+IN
OUT
AAA+V IN+IN
OUT
BBB
+B+
1A2345678
IN V+IN
OUT
AAA+V IN+IN
OUT
BBB
+B+
1A2345678
IN V+IN
OUT
AAA+V IN+IN
OUT
BBB
+B+
(MX12/6 MAIN, MA20/6 MAIN: IC101,IC201,IC301,
 IC401, IC501, IC601, IC701, IC801, ICD02, ICE02, 
 ICF04, ICG04, ICH04, ICI31, ICI61) (MX12/6 MAIN,...