Power Supply Circuits - Icom IC-M87 Service Manual

4-3-2 VCO CIRCUITS (MAIN UNIT)
The VCO circuits contain a separate RX VCO (Q41, D31–
D34) and TX VCO (Q51, D35–D38). The oscillated signal is
amplifi ed at the buffer amplifi ers (Q61, Q62) and is then ap-
plied to the T/R switches (D91, D92).
The receive 1st LO (RX) signal from the T/R switch (D92) is
applied to the 1st mixer (Q191).
The transmit (TX) signal from the T/R switch (D91) is applied
to the buffer amplifi er (Q91).

4-4 POWER SUPPLY CIRCUITS

4-4-1 MAIN UNIT VOLTAGE LINE
Line
HV The voltage from the attached battery pack.
The same voltage as the HV line (battery
voltage) which is controlled by the power
VCC switch (VR unit; R801). The output voltage is
applied to the drive (Q101) and power ampli-
fi ers (Q111), etc.
Receive 5 V controlled by the R5V regulator
circuit (Q322) using the "R5VS" signal from
R5V the CPU (IC661, pin 89). The output voltage
is applied to the RF amplifier (Q165), 1st
mixer (Q191), IF amplifi er (Q211), etc.
Transmit 5 V controlled by the T5V regulator
circuit (Q323) using the "T5VS" signal from
T5V the CPU (IC661, pin 90). The output voltage
is applied to the buffer amplifier (Q91) and
antenna switch (D131), etc.
Common 5 V converted from the M5V line at
the V5V regulator circuit (Q321). The output
V5V
voltage is applied to the VCO circuits (Q41,
Q51), etc.
4-4-2 LOGIC UNIT VOLTAGE LINE
Line
Common 5 V converted from the VCC line
at the CPU5V regulator circuit (IC551). The
CPU5V
output voltage is applied to the CPU (IC661),
RESET IC (IC581), EEPROM (IC591), etc.
Common 5 V converted from the VCC line at
the M5V regulator circuit (Q551–Q553). The
M5V output voltage is applied to V5V, R5V, T5V
regulator circuits (MAIN unit; Q321–Q323),
etc.
Common 5 V converted from the M5V line at
the S5V regulator circuit (Q561). The output
S5V
voltage is applied to the microphone ampli-
fi er (IC471), scrambler switch (IC481), etc.
Description
Description
4-5 PORT ALLOCATIONS
4-5-1 CPU (LOGIC UNIT; IC166)
Pin Port
number name
1 BEEP
2 VSSTB
3 EXSTB
4 DASTB
5 PLSTB
10 SDATA
11 SCLK
12 ESCK
13 ESDA
28 WETIN
29 EXTSV
30 BATTV
31 TDETV
32 NOISV
33 RSSIV
34 LOINV
35 TEMPV
36 CDECV
38 ATIS
CONT1,
75, 76
CONT2
LEDS1,
77, 78
LEDS2
79 STXMS
80 MICMS
4 - 4
Description
Output beep audio signals.
O u t p u t s s t r o b e s i g n a l f o r t h e
scrambler IC (MAIN unit; IC381, pin
10).
Outputs strobe signal for the expander
IC (MAIN unit; IC341, pin 1).
Outputs strobe signal for the D/A
converter (MAIN unit; IC251, pin 6).
Outputs strobe signal for the PLL IC
(MAIN unit; IC1, pin 11).
Outputs serial data for the PLL and
scrambler ICs, etc.
Outputs serial data for the PLL and
scrambler ICs, etc.
Outputs clock signal for the EEPROM
(IC591).
I/O port for the EEPROM data signal
(IC591).
Input port for the transceiver's internal
inundation detection.
Input port for the external terminal
connecting detection.
Input port for the attached battery
voltage detection.
Input port for the transmit RF level
detection.
Input port for the noise level detection.
Input port for the RSSI voltage level
detection.
Input port for the VCO lock voltage
level detection.
Input port for the transceiver's internal
temperature detection.
Input port for CTCSS/DTCS detection.
Outputs ATIS wave form.
Output LCD contrast control signals.
Output LCD and key's backlight
dimmer control signal.
Outputs the scrambler switch (IC481,
pin 3) control signal.
Low : While the scrambler function
OFF.
Outputs the scrambler switch (IC481,
pin 7) control signal.
Low : While the scrambler function
ON.