Digital Control Circuit; Modulation Output Path; Recoding A Message; Constant Received Audio Recording Function - Kenwood TS-590S Service Manual

TS-590S

2) Modulation output path

The AF signal processed in DSP (IC301) is output as
analog in DAC (IC75, IC78) and then amplifi ed by the active
fi lter (IC73, IC76).
The signal that passed through the active fi lter (IC73) is
sent to ACC2 output signal (ANO).
The signal that passed through the active fi lter (IC76) is
sent to USB output signal (UAI).

3) Recoding a message

Signals input from the microphone are processed in ADC
(IC66), passed through DSP, and then enter DAC (IC75).
The signals output from DAC (IC75) pin 11 are sent to
the Optional unit (VGS-1) and recorded.

■ Constant received audio recording function

1) Recording
A part of received audio signal is processed in ADC (IC66),
goes through DSP (IC301), and then enters DAC (IC75). The
signals output from DAC (IC75) pin 11 are sent to the Op-
tional unit (VGS-1) and recorded. The recording level is auto-
matically compensated to become constant and you cannot
randomly change the level.
2) Playback
The output signal (VAO) from the Optional unit (VGS-1) is
input into ADC (IC83), goes through DSP (IC301), and output
as AF from DAC (IC72). Playback volume is controlled by
DSP.
IC66
ADC (MIC, RIF/DET)
IC72
DAC (AF, TIF/MOD)
IC75
DAC (ANO, VGS-AI)
IC78
DAC (USB-AO, AGCV)
IC83
ADC (VGS-AO, ANI/USB-AI)
18
CIRCUIT DESCRIPTION
IC304
OR
IC305
IC301
NAND
DSP
IC317
OR
X301
X'tal
(24.576MHz)
Fig. 15 Digital control circuit
■ Other functions
1) Playing a message (monitor)
The output signal (VAO) from the Optional unit (VGS-1) is
input into ADC (IC83), goes through DSP (IC301), and output
as AF from DAC (IC72). Playback audio is controlled by DSP.
2) Playing a pre-recorded voice message
The above-mentioned signal path is also used for playing
a pre-recorded voice message.

Digital Control Circuit

■ Outline
The digital control circuit consists of the Control unit's
(X53-446 A/3) main MCU (IC306), EEPROM (IC309), reset IC
(IC307), and DSP (IC301). (Refer to Fig. 15)
■ Main MCU and its periphery
The main MCU (IC306) operates at the power supply
voltage of 3.3V, and the clock frequency of 22.1184MHz
which is 11.0592MHz doubled in the main MCU. Around
the main MCU, EEPROM for backup, power supply voltage
monitoring circuit which includes a reset circuit, 3-state out-
put buffer (IC311) for DSP control are connected. When the
power supply is OFF, the mode is switched to stop mode in
order to reduce the standby current.
■ Around the DSP
The DSP (IC301) operates at the power supply voltage of
3.3V and 1.25V and clock frequency of 221.184MHz which
is 24.576MHz multiplied by 9 in the DSP. Around DSP, fl ash
memory (IC302) for storing programs, and DAC (IC66, IC83)
and DAC (IC72, IC75, IC78) for controlling signals are con-
nected.
IC302
Flash
memory
(512k
16bit)
IC306
Main MCU
IC311
Buffer
X302
X'tal
(11.0592MHz)
IC307
Reset circuit
Reduced voltage detection
Over voltage detection
Panel MCU
IC309
EEPROM
PC (RS-232C)
(USB)
External AT