Icom IC-M401EURO Service Manual page 34

11-3 HM-132
MC1
MIC
PTT
S2
UP
S3
DN
S4
16/9
C1 R1
470 P 12 k
S1
W2
W1
R2
6.8 k
R3
15 k
UP_ON
DN_ON
16/9_ON 3.8V
R4
33 k
PTT
MICG
MIC
PTTG
2.0V
3.0V
CHASSIS UNIT W1
PTT
1
MICG
2
MIC
to MAIN unit J4
3
GND
4
KEYM
1
GND
2 to LOGIC board J3