KENWOOD TK7150
Manual de Servicio

TK-7150
CIRCUIT DESCRIPTION
5-3. DSP Circuit
The DSP circuit filters transmit/receive audio signal and encode/decode signalling (QT, DQT, MSK, DTMF, 2-Tone, LTR ID). This circuit consists of IC710, IC706, IC707, IC708, IC709 and IC713. The receive audio signal is converted from analog to digital by IC713 with a sampling frequency of 19.2kHz. The digitized audio signal is sent to DSP (IC710) to process the signalling signal and audio signal. The processed digital audio signal is fed to CODEC (IC713), converted from digital to analog, and the analog signal is output from pin 16 (AOUTR). The transmit audio signal coming from IC714 (A/2) is amplified by IC712 (B/2), fed to pin 3 (AINL) of CODEC (IC713), and converted from analog to digital at a sampling frequency of 19.2kHz. The digitized transmit audio signal is AGC-processed, pre-emphasized and filtered at 300Hz to 3kHz by DSP (IC710), and the resulting signal is feed back to CODEC (IC713), and converted from digital to analog, and the analog signal is output from pin 15 (AOUTL). IC706, IC707, IC708 and IC709 are interface IC between the CPU operated at 5.0V and the DSP operated at 3.3V. dio : turn on). When IGN falls, the CPU (IC701) output the pulse to IC102 set line to reverse the output Low � High after the programmed time expire (Timed power off function). If 24V is supplied to the radio by mistake, Q102 turns on, Q101 turns off, the power is forced to be turned off. This circuit consists of IC104 (8V), IC105 (5V), IC106 (3.3V), IC108 (3.3V) and IC107 (1.8V).

6. Display Circuit
The display unit consists of CPU (IC904), LCD assembly, LED, and other components. Channels are changed by the rotary switch (S1). The up/ down signals from the rotary switch enter the CPU (IC904), and converted to a serial data signal, and are sent to the CPU (IC701) in the TX-RX unit. The on/off signals of keys other than the power switch, and the PTT and HOOK signals, are converted to serial data and sent to the CPU (IC701) in the TX-RX unit. Data is displayed on the 12 digits and 3 digits dot matrix alphanumeric display.

5-4. Power Supply Circuit
The voltage is always applied from +B. D103 protects IC102 (DFF) against overvoltage. Pulses from power switch are input to the IC102 clock line and the CPU (IC701). These clock pulses reverse the output High (radio : turn off) � Low (radio : turn on), do not reverse the output Low � High. The CPU (IC701) output the pulse to IC102 set line to reverse the output Low � High. IGN is input to the IC102 reset line and the CPU (IC701). When the IC102 reset voltage rise, the output goes Low (ra+B R112 D103 AVR D104 SW D106 SW D102 SW Q102 SW Q103 SW Q101 SW SB

7. RS-232C Circuit
The RS-232C circuit connects the RS-232C serial port of a personal computer directly to this model to perform FPU operation (Read and Write). The FPU operation can also be performed by connecting a programming cable (KPG-46) to the local microphone on the front panel. The 232C driver IC (IC703) changes the TTL-232C level. The firmware can only be rewritten with the local microphone on the front panel.
DM PTT LCD PTT HK SW Q907 SW D912 Q906 TX LED Q903 SW D907 REF AF VR IRS ES2 MIC MIC HK X901 12MHz 5V IC904 CPU RST

D908 D909 D910

Q902 SB SW ME BEAT SHIFT POWER SW E 8LC 8 PSW

AVR IC901

SB RST

D915 RX LED

PF1 PF2 PF3 PF4 PF5 PF6 Q109,110 SW IC102 DFF Q111 SW

D105 SW D109 AVR

Q112,113 SW IC701 CPU Q710 SW

Q108 SW SB Q713 SW

D914 D913 D911

IGN

PSW

1

J901 INT SP Rotary SW

Fig. 6

Power supply circuit
Q904 SW SW Q908

Key back lamp

Fig. 7 Display circuit 15