Yamaha Mx12.6 Service Manual

							   
 
 
to IN8-CN404
(MX20/6 only)to DCJK1/2
-CN101 or CN108to DCJK2/2-CN302
GAIN
HIGH
MID
LOW
AUX1
AUX2
EFFECT
1-2
3-4
ST
1 2 3 4 5 6 7 8 9/10DIGITAL EFFECT
PAN
POST POST POST POST POST POST POST POST POST POST
BALST GRAPHIC EQUALIZER
11/12 to DCJK2/2-CN301 to DCJK1/2-CN106 (MX12/6 only)
Component side
Component side Component side MAIN2/4 Circuit Board
MAIN1/4 Circuit Board
MAIN3/4 Circuit Board
to DCJK1/2-CN105
Component side MAIN4/4 Circuit Board
CIRCUIT BOARDS
3NA-V6258102
C
C
C
C
(MX20/6)
(MX12/6)INSERT I/O
INSERT I/O
34 2 1
1 9
2 10
3 11
4 12
5 13
6 14
7 15
8 16
(MX20/6)
(MX12/6) 19
2 10
3 11
4 12
5 13
6 14
7 15
8 16
R
PEAK
+5
+3
+1
0
-1
-3
-5
-7
-10
-15
-20
1-2 L POWER
PEAK
MIC
LINE
MX12/6
MX20/6
21
3-4
STGROUP
TAPE IN 
						

							(MX12/6 only)
MAIN2/4 Circuit Board
MAIN2/4 Circuit Board
MAIN3/4 Circuit Board
MAIN4/4 Circuit Board
Pattern sidePattern side Pattern side
Pattern side MX12/6
MX20/6
22 
						

							23 MX12/6
MX20/6
to ACto Power Switch CN105: to MAIN4/4-CN305
to MAIN3/4
-CN306 CN103:
CN104:
CN109:
to MAIN1/4-CN201 to MAIN1/4-CN202
to Power Transformer
CN107:to MAIN1/4-CN207(MX12/6)
to IN8 1/2-CN403(MX20/6)CN108:to MAIN1/4-CN207(MX12/6)
to IN8 1/2-CN403(MX20/6)
L REC OUT TAPEIN 1 2 3 4 R L(MONO) EFFECT AUX2 SEND
AUX1
R
RETURN
ROUP OUT
CIRCUIT BOARDS
 
DCJK1/2 Circuit Board
Component side
Component side 
DCJK2/2 Circuit Board
3NA: V626340  1 
						

							MX12/6
MX20/6
24
A
A
to DCJK1/2
-CN107
GAIN HIGH MI
D
34 567 8 2INSERT I/O
1345678 2INSERT I/O
1
34 5 6 7 8 2 1
MICLINE
 
IN8 1/2 Circuit Board
  (MX20/6 only) 
IN8 2/2 Circuit Board
  (MX20/6 only) 
						

							25 MX12/6
MX20/6
A
A
to MAIN1/4-CN208
HIGH MID AUX1 AUX2LOW EFFECT
PANBAL
Component side3NA: V626330  2 
						

							MX12/6
MX20/6
26
A
A 
IN2/1 Circuit Board 
						

							27 MX12/6
MX20/6
A
A
Pattern side Pattern side
 
IN2/2 Circuit Board 
						

							MX12/6
MX20/6
28
INSPECTIONS
1. Preparation
Set the operation elements of the equipment as described below unless otherwise specified.
1-1. Initial conditions
Power supply voltage within AC100V ± 2%
Environment conditions Temperature: 25 ± 5°C Humidity: 65 ± 5%
1-2. Panel operation elements
Channel input section (CH1 to CH8)
GAIN control: MAX (-60dB)
HI, MID, LO EQ level: Center
AUX1, AUX2, EFFECT level control: MAX
AUX2 POST switch: OFF (PRE)
PAN control: L (turned counterclockwise fully)
1-2, 3-4, ST assign switch: ON when taking measurement only, OFF otherwise
Fader: MAX
Stereo input (MX12/6: 9/10, 11/12 MX20/6: 17/18, 19/20)
GAIN control: MAX (-34dB)
HI, MID, LO EQ level: Center
AUX1, AUX2, EFFECT level control: MAX
AUX2 POST switch: OFF (PRE)
BAL control: L (turned counterclockwise fully)
1-2, 3-4, ST assign switch: ON when taking measurement only, OFF otherwise
Fader: MAX
Master control section
GROUP 1 to 4 Master fader (60mm): MAX
STEREO GROUP 1/2, 3-4 switch: OFF
Master fader (Stereo 100mm): MAX
MONO master level control: MAX
AUX1, 2, EFFECT SEND master level control: MAX
DIGITAL EFFECT PROGRAM select switch: VOCAL ECHO 1
DIGITAL EFFECT PARAMETER control: MIN
DIGITAL EFFECT ON switch: OFF
DIGITAL EFFECT (AUX1, AUX2, ST level control): MAX
AUX RETURN (AUX1, AUX2, ST level control): MAX
TAPE IN (ST level control): MAX
METER & MONITOR source select switch: OFF
(ST/TAPE IN, ST/GROUP, GROUP 1-2/GROUP 3-4)
C-R/PHONES level control: MAX
ST GRAPHIC EQUALIZER level control: Center
(125, 250, 500, 1k, 2k, 4k, 8kHz)
Others
MX12/6, MX20/6: PHANTO switch (with LED) [8ch/sw]: OFF 
						

							29 MX12/6
MX20/6
*1 Measure with the PAN control set at the center position. For others, turn the PAN control counterclockwise fully for the odd
number OUT of L and GROUP and turn it clockwise fully for the even number OUT of R and GROUP. Also, for MONO OUT,
check both when the PAN control is turned clockwise fully and counterclockwise fully.
*2 Only CH1 can be checked.
*1 Measure with the BAL control set at the center position. For others, turn the BAL control counterclockwise fully for the odd
number OUT of L and GROUP and turn it clockwise fully for the even number OUT of R and GROUP.
1-3. Input/output/load
Unless otherwise specified, the input signal and the load resistance of the output terminal are as described below.
Input signal 1kHz, -80dBs, sine wave, signal source impedance Rs=150ohm
Load resistance
C-R/PHONES (L, R): 40ohm (3W or more)
INSERT OUT, REC OUT: 10kohm
LAMP: 30ohm (20W or more)
Other output: 600ohm
2. Inspections
2-1. Gain
Check that the gain is obtained at the output level within the range specified in Tables 1 to 5 below.
When Ò8/16Ó is used for channels, for example, the number before the slash (/) is applicable to MX12/6 and that after the slash
(/) is applicable to MX20/6.
Table 1 Input terminal  CH INPUT (1 to 8/16)Unit [dBs]
Input Input GAIN ST L OUT ST R OUT MONO GROUP1 to 4 AUX1 AUX2 OUT EFFECT
level OUT OUT OUT POST SW POST SW OUT
OFF ON
MIC -80 MAX +1 ± 2  *1 +1 ± 2  *1 -3 ± 2  *2 +4 ± 2 -4 ± 2 -4 ± 2 +6 ± 2 +6 ± 2
GROUP TO ST SW 1-2(3-4) ON--- ---- ---- ---- ---- ----
+14 ± 2 +14 ± 2
-36 MIN +4 ± 2 --- --- --- --- --- --- ---
LINE -54 MAX +4 ± 2 --- --- --- --- --- --- ---
Table 2  Input terminal Unit [dBs]
Input terminal Input level GAIN INSERT OUT 1 to 4/8 REC OUT L REC OUT R
MIC1 to 4/8 -80 MAX -20 ± 2 --- ---
CH INSERT IN 1 0
Unspecified--- +2.2 ± 2 -2.2 ± 2
CH INSERT IN 2 to 4/8 0Unspecified--- +2.2 ± 2 ---
Table 3  Input terminal  STEREO INUnit [dBs]
Input Input Input GAIN ST L ST R MONO GROUP1 to 4 AUX1 AUX2 OUT EFFECT
terminal level OUT OUT OUT OUT OUT POST SW POST SW OUT
OFF ON
PHONE 9/17L -54 MAX
+1 ± 2  *1--- +4 ± 2 --- -7 ± 2 -7 ± 2 +3 ± 2 +3 ± 2
JACK 11/19L
10/18R ---
+1 ± 2  *1--- +4 ± 2 -7 ± 2 -7 ± 2 +3 ± 2 +3 ± 2
12/20R
PIN 9/17L +4 ± 2 --- --- --- --- --- --- ---
JACK 11/19L
10/18R --- +4 ± 2 ---- ---- --- --- --- ---
12/20R
PHONE 9/17L -10 MIN +4 ± 2 --- --- --- --- --- --- ---
JACK 11/19L
10/18R --- +4 ± 2 --- ---- ---- ---- ---- ----
12/20R 
						

							MX12/6
MX20/6
302-2. Frequency response
In the state checked in 2-1 above, check the frequency response measured at 20Hz and 20kHz of each input/output is within
the range of 0+1/-2.5 dB of the 1kHz frequency as reference value (0dB). However, the level at 20Hz when the GAIN volume is
maximum should be within the range of 0+1.0/-4.5 dB of the 1kHz frequency as reference value (0dB).
For Table 1, check at every OUT for CH 1 only, and at ST L OUT only for CH 2 and other channels.
For ÒL/MONOÓ of Table 4, check at ST L OUT and ST R OUT only.
2-3. Channel equalizer characteristics
Check the output obtained at GROUP1 OUT in the case of CH INPUT and ST CH INPUT L and at GROUP2 OUT in the case
of ST CH INPUT R when LO, HI and MID of INPUT are moved respectively. Its level in < frequency should be within the range
specified in the table below based on the output level at the EQ gain control center click position as reference value.
If the check result of the channel equalizer characteristics is not within the specified range, vary the applied frequency within the
range of ± 20% of the specified frequency and check that the above variation width is obtained.
2-4. Graphic equalizer (GEQ) characteristics
Check the output obtained at ST L OUT and ST R OUT when the GEQ fader is moved. Its level in < frequency should be within
the range specified in the table below based on the output level at the center click position as reference value.
If the check result of the graphic equalizer characteristics is not within the specified range, vary the applied frequency within the
range of ± 20% of the specified frequency and check that the above variation width is obtained.
Table 4  Input terminal  RETURN L, R Unit [dBs]
Input terminal Input level STEREO L OUT STEREO R OUT AUX1 OUT AUX2 OUT
L/MONO 0 +16 ± 2 +16 ± 2 +15 ± 2 +15 ± 2
R 0 --- +16 ± 2+9 ± 2+9 ± 2
Table 5  Input terminal  TAPE IN Unit [dBs]
Input terminal Input level ST OUT L ST OUT R PHONES L PHONES R
TAPE IN L -27.8 -1 ± 2 --- +3.5 ± 2 ---
TAPE IN R -27.8 --- -1 ± 2 --- +3.5 ± 2
Unit [dBs]
EQ control EQ GAIN
Applied frequency Variation width
HI MAX 10kHz +12 ± 2
MIN -12 ± 2
MID MAX 2.5kHz +15 ± 2
MIN -15 ± 2
LO MAX 100Hz +12 ± 2
MIN -12 ± 2
Unit [dBs]
Fader name Fader
Applied frequencyVariation width
125Hz MAX 125Hz +12 ± 2
MIN -12 ± 2
250Hz MAX 250Hz +12 ± 2
MIN -12 ± 2
500Hz MAX 500Hz +12 ± 2
MIN -12 ± 2
1kHz MAX 1kHz +12 ± 2
MIN -12 ± 2
2kHz MAX 2kHz +12 ± 2
MIN -12 ± 2
4kHz MAX 4kHz +12 ± 2
MIN -12 ± 2
8kHz MAX 8kHz +12 ± 2
MIN -12 ± 2