Icom IC-756PROII Service Manual page 20

(8) MAIN-A unit; IC3653
Pin Port
number name
Outputs strobe signals for the output
13 BSTB expander ICs (RF-A unit; IC901,
IC902, IC905).
Outputs
ANTS ([ANT1] or [ANT2]) select signal.
14
High: When the [ANT2] is selected.
Outputs strobe signals for the output
15 FSTB
expander (CTRL board; IC11).
Outputs strobe signals for the D/A con-
16 ASTB
verter (IC3751).
Outputs strobe signals for the output
17 MSTB
expander ICs (IC3752, IC3753).
Outputs control signal for the AF mute
switch (IC331).
18 AFMS
High: When the [AF] control is set to
Outputs squelch mute control signal,
19 SQLS applied to the squelch gate (IC301).
High: Squelched
(9) MAIN-A unit; IC3654
Pin Port
number name
Outputs squelch control signal for the
SQSS [MIC] and [ACC1] connectores.
12
High: Squlch opend. (RX LED ON)
Outputs control signal for the internal
13 SPS speaker ON/OFF select relay (RL351).
High: Internal speaker is ON.
Outputs strobe signals for the optional
14 SSTB
UT-102 SPEECH SYNTHESIZER.
Outputs chip select signal for the audio
15 VCS
recoder (IC3001).
Outputs external antenna tuner (AH-3)
start signal.
16 ESTA
Low : When the [TUNE] switch is
DSFR, Outputs control signal for the DSP IC
17, 18
DSFW (DSP-A board; IC2001).
Description
the antenna connector
maximum counter clockwidth.
Description
pushed.
(10) MAIN-A unit; IC3752
Pin Port
number name
4 NBS
6 MSL1
7 MSL2
12 VOSL
14 MISL
(11) MAIN-A unit; IC3753
Pin Port
number name
4 AMS
5 PHFS
6 P50S
7 MODS
11 DSRS
14 FMNS
3 - 14
Description
Outputs control signal for the noise
blanker switch (Q3751, Q3752).
High: When the [NB] switch is ON,
except in FM mode.
Outputs audio select signal for the TX
monitor function.
High: During monitoring in SSB or
RTTY mode.
Outputs audio select signal for the TX
monitor function.
High: During monitoring in AM or FM
mode.
Outputs analog switch (IC3005) con-
trol signal for the audio recoder's
(IC3001) output.
High: When the audio recoder's out-
put to the AF circuit.
Outputs analog switch (IC3002) con-
trol signal for input of the microphone
amplifier (IC461).
High: Except the microphone input is
selected.
Description
Outputs AM mode select signal for the
AGC and APC circuit.
High: When AM is selected.
Outputs HF band RF power control
signal.
High: When 0.03–29.999999 MHz
band is selected.
Outputs 50 MHz band RF power con-
trol signal.
High: When 30–60 MHz band is
selected.
Outputs 2nd IF filter (FI131 or FI133)
select signal.
High: When transmitting in AM or FM
mode. (FI131 is ON)
Outputs reset signal for the DSP circuit
and etc.
Outputs FM deviation control signal.
High: When FM-N is selected.