Icom IC-M422 Service Manual page 12

4-7 PORT ALLOCATIONS (continued)
Pin
Port name
NO.
Input port for the [DSC] key (LOGIC BOARD; S7).
71 DSC
Low: [DSC] key is pushed.
Input port for the [PA] key (LOGIC BOARD; S6).
72 PA
Low: [PA] key is pushed.
Input por t for the [CH/WX] key (LOGIC
73 CH/WX BOARD; S5).
Low: [CH/WX] key is pushed.
Input port for the [SCAN] key (LOGIC BOARD; S4).
74 SCAN
Low: [SCAN] key is pushed.
Input port for the [16] key (LOGIC BOARD; S3).
75 CH16
Low: [16] key is pushed.
Input port for the [Z] key (LOGIC BOARD; S2).
76 DOWN
Low: [Z] key is pushed.
Input port for the [Y] key (LOGIC BOARD; S1).
77 UP
Low: [Y] key is pushed.
Outputs dimmer control signal to the LCD control
138 DIM
circuit (LOGIC BOARD; Q2, Q3).
139 BEEP Outputs beep signal to the AF amplifi er (IC9, pin 1).
• While transmitting:
Outputs DSC encode signal as "DSENC"
to the LPF (IC8, pin 5) via the buffer amplifi er
(LOGIC BOARD; IC5, pins 1, 3).
141 DS/BPF
• While receiving:
Outputs tuning signal as "BPFV" to the
tunable BPFs (D25–D28) via buffer amplifi er
(LOGIC BOARD; IC5, pins 5, 7).
Description
4 - 5