Kenwood TS-990S Service Manual

Also see for SP-990: Instruction manual

Contents

TS-990S53COMPONENTS DESCRIPTIONRef. No. Use/Function Operation/Condition/CompatibilityIC5 Shift registerQ5: PSEL “H” when preselectoris selected (1.7975~29.8MHz)Q6: PSAMP “H” when preselec-tor amp is ON (1.7975~29.8MHz/30~60MHz (only PREOFF))Q7: LHF “H” when BPF of30k~522kHz or 522k~1.705MHzor 35-40MHz is selectedQ8: NRLY “H” when any oneof MBPF5, 7, 9, 11, 12, 13, 14 isselectedIC7 Mixer 1st receiving mixer (RF8.248MHz)IC8 Exclusive ORgate Local signal drive circuitIC9 Main RX FM IC RX FM demodulatorIC10 OP amplifi er 2nd IF ampIC11 Multiplexer Receiver output, FM (AF) andSSB/AM/CW (IF) changeoverIC12 OP amplifi erA/2: RX FM noise squelch volt-age amplifi erB/2: RX FM AF signal amplifi erIC13 OP amplifi er A/2: No usedB/2: MAGC voltage amplifi erQ1 Switching6dB ATT changeover relay (K1)control (OFF when main 6dB ATTis selected)Q2 Switching12dB ATT changeover relay (K2)control (OFF when main 12dBATT is selected)Q3 SwitchingLHF changeover relay (K3) con-trol (ON when MBPF1 or MBPF2is selected (LHF is “H”))Q4,5 SwitchingPower supply switch of RX14(ON when main receiver is active(MRXC is “H”))Q6 SwitchingLHF changeover relay (K4) con-trol (ON when MBPF1 or MBPF2is selected (LHF is “H”))Q7 SwitchingON when BPF of522kHz~1.705MHz is selected(ON when MBPF2 is “H”)Q8 Switching ON when BPF of 30~522kHz isselected (ON when MBPF1 is “H”)Q9 SwitchingPreselector amplifi er changeoverrelay (K5) control (ON whenPSAMP is “H”)Q10,11 Amplifi er Preselector amplifi erQ12 Switching PREAMP1 changeover relay (K6)control (ON when MPRE1 is “H”)Q13 Switching PREAMP2 changeover relay (K7)control (ON when MPRE2 is “H”)Q14,15 SwitchingPower supply switch of RX14 forPREAMP1 and postamp (ONwhen MPRE1 or MPRE2 is “H”)Q16 Buffer amplifi er Noise blanker input bufferRef. No. Use/Function Operation/Condition/CompatibilityQ18 Amplifi er Noise blanker post amplifi erQ19 SwitchingPower supply switch of RX8(ON when main receiver is active(MRXC is “H”))Q20 Amplifi er Pre-amplifi er 2Q21 Amplifi er Noise blanker amplifi er 2Q22,23 SwitchingPower supply switch of RX14 forPREAMP2 (ON when MPRE2 is“H”)Q24 Amplifi er Noise blanker amplifi er 2Q25,26 Amplifi er Pre-amplifi er 1Q27 SwitchingPower supply switch of RX8(ON when main receiver is active(MRXC is “H”))Q28 Amplifi er Noise blanker amplifi er 3Q29 Switching PREAMP2 changeover relay (K8)control (ON when MPRE2 is “H”)Q30 Amplifi er Noise blanker amplifi er 3Q31 Switching PREAMP1 changeover relay (K9)control (ON when MPRE1 is “H”)Q32 Amplifi er Noise blanker AGC control ampli-fi erQ33 Amplifi er Noise blanker amplifi er 4Q34 SwitchingATT switch (ON when MBPF14 is“H”, except MPRE1 or MPRE2 is“H”)Q35 Switching Audio mute signal is generatedQ36,37 Buffer amplifi er Noise blanker bufferQ38 Switching Audio mute signal is generatedQ39,40 SwitchingPower supply switch of RX5 (ONwhen main receiver is active(MRXC is “H”))Q42,43 SwitchingPower supply switch of FM5 (ONwhen FM mode is active (MRXFMis “H”))Q44 Switching 6dB IF ATT switch (ON whenMHFRGC is “H”)Q45 Switching 10dB IF ATT switch (ON whenM50RGC is “H”)Q46 Amplifi er Post amplifi erQ47,48 SwitchingPower supply switch of NFM8 (ONwhen except FM mode is active(MRXFM is “L”))Q49 Amplifi er IF amplifi erQ50 SwitchingPower supply switch of NFM8 (ONwhen except FM mode is active(MRXFM is “L”))Q51 SwitchingPost amp changeover relay (K10)control (ON when MPRE1 orMPRE2 is “H”)Q52 Amplifi er IF amplifi erQ53,54 Switching Blanking switch (OFF whenMBLNK is “H”)