Yamaha Mg12.4 Service Manual

21 MG12/4
MG16/4
 14

22 MG12/4
MG16/4
4. Side Cover
(Time required : About 5 minutes each.)
4-1. Remove the bottom cover. (See procedure 2)
4-2.
Side Cover L :
4-2-1. Remove the rack mount angle L. (See procedure 1)
4-2-2.Remove the screw marked [430A], three (3) screws
marked [430B], three (3) screws marked [440A] and
two (2) screws marked [450A]. The side cover L can
then be removed. (Fig. 2)
4-3.
Side Cover R :
4-3-1. Remove the rack mount angle R. (See procedure 1)
4-3-2. Remove the PS circuit board. (See procedure 3)...

23 MG12/4
MG16/4(Fig. 2) [430]: Bind Head Tapping Screw-S 3.0 x 6 MFZN2B3 (WE877800)
[440]: Bind Head Tapping Screw-S 3.0 x 6 MFZN2W3 (WE877900)
[450]: Hex. Socket Set Screw-S 3.0 x 6 MFZN2B3 (WF419300)
[460]: Bonding Tapping Screw-B 3.0 x 10 MFZN2B3 (WE878000)
Side cover RSide cover L
[440B]
[440B]
[440B][440A]
[440A]
[440A] [450A]
[450A] [450B]
[450B] [450C]
[450C]
[430B]
[430B] [430B] [430D]
[430D] [430D]
[460] [460]Fader knobs
Hexagonal nuts
Hexagonal nuts
[430C]
MIX
[430A]
Volume knobs
MAIN
MAIN...

24 MG12/4
MG16/4
[420] [420] [420] [420] [420]
Push HPF buttons
Hooks
Hexagonal nuts
MIX1 support (upper)
MIX1 support (lower)
Push PFL buttons
Meter cover
Push HPF buttons
¢Ø»ï0/
TTŸZ£
Push HPF buttons
MIX2 support
Sleeve ON buttons
Push PFL buttons
[420]: Bind Head Tapping Screw-S 3.0 x 6 MFZN2W3 (WE877900)
(Fig. 3)Meter reflector
MAIN
JACK
2/2
5-8. Remove the hexagonal nut. The JACK 2/2 circuit board
can then be removed from the MIX1 support. (Fig. 3)
5-9.Pull out the eighty-nine (89) volume...

25 MG12/4
MG16/4
6. Power Switch and AC Connector
(Time required : About 6 minutes each.)
6-1. Remove the rack mount angle L and R.
(See procedure 1)
6-2. Remove the bottom cover. (See procedure 2)
6-3. Remove the PS circuit board. (See procedure 3)
6-4. Remove the side cover R. (See procedure 4)
6-5. Remove the power switch by bending its claw.
(Photo 2)
6-6. To remove the AC connector, remove the hexagonal nut
and flat washer. (Photo 2)
(Photo 2)
 ?o

26 MG12/4
MG16/4

 IC BLOCK DIAGRAM
NJM2068M-D(TE2) (X3505A00)
Dual Operational Amplifier
MG12/4 MAIN, MG16/4 MAIN: IC502, 503, 
        IC702, 703, 902-904, ICA02-04, 
        ICB01-03, ICC01-03, ICD01-03,
        ICE01, 03, ICF01, ICG01-05
MG16/4 MAIN: IC102, 103, 302, 303
NJM4556AL (XP844A00) 
Dual Operational Amplifier 
MG12/4 MAIN, MG16/4 MAIN: ICH03
NJM4580ED (XT157A00)
Dual Operational Amplifier
MG12/4 MAIN, MG16/4 MAIN: IC501, 601, 
        IC701, 801, 901, ICA01, ICE02, 
        ICF02, ICG06,...

27 MG12/4
MG16/4
to MAIN-CNF01
to Power switch, AC connector
: not installed

 CIRCUIT BOARDS
MG12/4 MAIN (X6346C0) ................................. 34/36
MG12/4 JACK 1/2 (X6353B0) ............................... 38
MG12/4 JACK 2/2 (X6353B0) ............................... 37
MG16/4 MAIN (X6345C0) ................................. 28/30
MG16/4 JACK 1/2 (X6254B0) .......................... 32/33
MG16/4 JACK 2/2 (X6254B0) ............................... 33
PS (X6343B0)...

28 MG12/4
MG16/4
GAIN
HPF
HIGH
MID
LOW
AUX1
PRE
AUX2
PA N
ST
PFL
1-2
1 2 3 4 5 6 7 8 9/10 11/12
PAN/BAL PAN/BA
PEAK PEAK PEAK PEAK PEAK PEAK PEAK PEAK PEAK PEAK
to JACK 1/2-CN171 to JACK 1/2-CN371 to JACK 1/2-CN571 to JACK 1/2-CN771 to JACK 1/2-CN971 to J
A
A
MG16/4 MAIN Circuit Board
MAIN: 2NA-WE52160 

29 MG12/4
MG16/4
0 11/12 13/14 15/16
BAL PAN/BAL BAL BAL STST
C-R/PHONES AUX2 AUX1
AUX2
TO ST
ST/
GROUP
AUX1
ST GROUP 1-2
PHANTOM
+48V
2TR IN
RETURN SEND
2TR IN
PEAK+5
+3
+1
0
-1
-3
-5
-7
-10
-15
-20 LSTR
12POWER
PEAK
2-CN971 to JACK 1/2-CNA71 to JACK 1/2-CND71 to JACK 1/2-CNE71 to JACK 1/2-CNG71 to PS-CN02
to JACK 2/2-CNH02
A
A
Component side
MAIN: 2NA-WE52160
¢
æ
¼£ 

30 MG12/4
MG16/4

MG16/4 MAIN Circuit Board
B
B
MAIN: 2NA-WE52160