Kenwood TS-990S Service Manual

Also see for SP-990: Instruction manual

Contents

TS-990S32CIRCUIT DESCRIPTION8-2. DSPs (IC202 and IC300) and the Peripheral Cir-cuitThere are two types of DSPs. The TXMRX-DSP (IC202)is used for transmission processing, main band reception,and RTTY/PSK31 encoding, and operates at an internalcore voltage of 1.2 V, external I/O voltage of 3.3 V, referenceclock frequency of 24.576MHz, and operating clock frequen-cy of 331.776MHz. The SRX-DSP (IC300) is used for sub-band reception and various signal path processing (exceptfor band scope and display processing and RTTY/PSK31decoding), and operates at an internal core voltage of 1.2V, external I/O voltage of 3.3 V, reference clock frequency of24.576MHz, and operating clock frequency of 258.048MHz.The SRX-DSP (IC300) supplies the BICK (SCLK96K)a n d L R C K ( L R C K 9 6 K ) fo r a n M C L K f r e q u e n c y o f24.576MHz and a sampling frequency (fs) of 96kHz to eachADC and DAC. The Flip Flop (IC380) divides the SCLK96Kand LRCK96K to generate the BICK (SCLK48K) and LRCK(LRCK48K) for an fs of 48kHz. The SCLK96K and LRCK96Kare supplied to the TXMRX-DSP (IC202) while the SCLK48Kand LRCK48K are supplied to the TXMRX-DSP and SRX-DSP.The Flash memories (IC203 and IC301) are used to storeeach DSP program, and the Latch ICs (IC200 and IC201)are used as an address decoder for the TXMRX-DSP use.The buffer (IC302) is used for the 8-port expansion input forthe SRX-DSP. The SRS-DSP exchanges transmission andreception data from the optical I/O (A650 and A651).The main MCU serves as a host. Therefore, the DSP-SubMCU (IC101) performs UART and SPI conversion inorder to enable communications between the host and eachDSP. The DAC (IC658) is connected to the DSP-SubMCUto control the electronic volume ICs (IC664 and IC664) incontrol of various functions, such as volume control, mutecontrol DSP reset release control, or boot control.When the DSP-SubMCU is in SPI communication withthe TXMRX-DSP (IC202) and SRX-DSP (IC300), the DSP-SubMCU serves as the master and each DSP serves as aslave.Fig. 36 Flow of audio clockIC300 SRX-DSPSCLK96K/LRCK96KSCLK48K/LRCK48KIC202TXMRX-DSPSCLK96K/LRCK96KSCLK48K/LRCK48KIC399NANDIC380Flipflop(Frequency devider)IC392 ADC(SRIF/ANI,UANI)IC397 DAC(TIF/MAGCV)IC398 ADC(MRIF/MIC)IC386 DAC(MUANO/SUANO)IC388 DAC(SAGCV/SSCPI)IC391 DAC(MANO/SANO)IC385 DAC(BEEP/MSCPI)IC389 ADC(MRECO/SRECO)IC390 DAC(SP1/SP2)IC397 DAC(MRECI/SRECI)IC381BufferIC382BufferIC383BufferSCLK96KLRCK96KSCLK48KLRCK48KSCLK_1SCLK_2LRCK_1LRCK_2MCLK_1MCLK_2MCLK96K MCLK48K8-3. Reception Signal Path (IF Signal/FM Wave De-tection to AF output)The signal (MRIF) in FM or other modes output from theCN137 on the RX unit (X55-313 A/2) is sent to the MRIFconnector (CN665) on the DSP unit (X53-453) and input intothe L channel of the ADC (IC398) through the active filters(IC675 and IC667). The TXMRX-DSP processes the MRIFsignal sampled by the ADC at a sampling frequency (fs) of96kHz.The signal (SRIF) in FM or other modes output from theCN600 on the TX-RX unit (X57-827 A/2) is sent to the SRIFconnector (CN670) on the DSP unit and input into the Lchannel of the ADC (IC392) through the active filters (IC670and IC678). The SRX-DSP processes the SRIF signal sam-pled by the ADC at a sampling frequency (fs) of 96kHz.The signal processed by each DSP is sent from the SRX-DSP to the DAC (IC390) and converted to an AF signal at anfs of 48kHz. The DAC outputs the SP1 signal for the L chan-nel and SP2 signal for the R channel.The signal output from the DAC passes through the ac-tive filter (IC650), and is converted to a certain voltage levelby the electronic volume ICs (IC664 and IC665). This signalmixed with the BEEP signal and MIXSP signal in IC673,and passes through the active filter (IC660 and IC661), andis applied to the AF power amplifiers (IC51 and IC52) andheadphone amplifi ers (IC50 and IC671).The SP1 signal input into the AF power amplifier is sentas a built-in speaker output from CN50 after the signal pass-es through the mute circuit. If an external SP1 is used, thesignal is sent from J50 (the built-in speaker and the externalSP1 cannot be used simultaneously.). The SP2 signal is sentfor an external SP2 from J51.The SP1 signal (for the L channel) and SP2 signal (forthe R channel) signal input into the headphone amplifier aresent from CN667 and connected to the PHONES jack on thefront panel.