TC-780 VHF/UHF Parts List 1
Contents
1. 41 780 Schematic Diagram u unsi s uu uu wau was upina aN 41 TC 780 VHF UHF Schematic 41 Specifications nn ete eem de si to e 42 HVT TC 780 Service Manual Manual Scope This manual is intended for use by experienced technicians familiar with similar types of communication equipment It contains all service information required for the equipment and is current as of the publication date Safety and General Information The following general safety precautions as would normally apply should be observed during all phases of operation service and repair of this equipment This equipment should be serviced by qualified technicians only Use only HYT supplied or approved antenna Turn off your radio prior to entering any area with a potentially explosive atmosphere To avoid electromagnetic interference and or compatibility conflicts turn off your radio in any facility where posted notices instruct you to do so When instructed to do so turn off your radio when on board an aircraft Any use of a radio must be in accordance with airline regulations or crew instructions To avoid possible interference with blasting operations turn off your radio when you are near electrical blasting caps in a blasting area or in areas posted Turn off two way radio Obey all signs and instructions For vehicles with an2. A SBC TSC 0609 SW S B VOL OUT 17601 2541745 AVR MOTOR SERVO A SW Q602 F MOTOR CON Figure 5 Power Switch Circuit Keypad and Display Circuit The display circuit is comprised of MCU U605 LCD module keyboard LED and other components The backlight enable pin LED EN is controlled by MCU When the pin LED EN is H the backlight shall be turned on 11 HVT Keyboar H SW Figure 6 Display Circuit TC 780 Service Manual 12 780 Service Manual No Port Name Pin Name Function Remarks Automatic power control Rx bandpass control Adjust APC and Rx bandpass 1 P94 DA1 APC TV O through DA 0 5V DTMF 2 Tone 5 Tone Beep output ALARM output DA generates waveform 2 P93 DA0 TONEO O Cannot output from speaker LCM data display module control 3 P92 LCM_SDI O data pin LCM clock display module control P91 LCM_SCK O clock pin P90 TONE_IN 2 5 input decode 6 BYTE BYTE BYTE Ground through resistor Pull down in operating mode and 7 CNVSS CNVSS CNVSS pull up when programming 9 Control transmit transient H disable transmit PA L enable 8 P87 XCIN DC_SW O transmit PA P86 XCOUT shift O Frequency shift 10 RESET RESET Reset when low level input PROG8 Crystal oscillator output pin 11 XOUT XOUT O Connect to crystal oscillator 12 VSS GND GND PROG7 Crystal oscilla
3. 4 TX5 RX RX1 RX2 RX3 RX4 RX5 gt Three point Adjustment MHz TX TX1 TX3 TX5 RX RX1 RX3 RX5 gt One point Adjustment MHz TX TX3 20 780 Service Manual RX RX3 7 Frequency Table of Five point Adjustment Frequency Band Point 1 MHz Point 2 MHz Point 3 MHz Point 4 MHz Point 5 MHz MHz 136 174 V TX1 136 TX2 145 5 TX3 155 TX4 164 5 TX5 174 RX1 136 15 RX2 145 65 RX3 155 15 RX4 164 65 RX5 173 85 400 470 U1 TX1 400 TX2 417 TX3 435 TX4 452 TX5 470 RX1 400 15 RX2 417 15 RX3 435 15 RX4 452 15 RX5 469 85 450 520 U2 TX1 450 TX2 467 5 TX3 485 TX4 502 5 TX5 520 RX1 450 15 RX2 467 65 RX3 485 15 RX4 502 65 RX5 519 85 8 After all reset is completed channel data corresponding to each frequency band in user mode is shown in the following table Channel Rx Frequency Tx Frequency Signalling Power Channel MHz MHz Spacing 1 RX1 TX1 None High 25KHZ 2 RX3 TX3 None High 25KHZ 3 RX5 TX5 None High 25KHZ 4 RX1 RX1 None Low 20KHZ 5 RX3 RX3 None Low 20KHZ 6 RX5 RX5 None Low 20KHZ 7 RX1 RX1 None Low 12 5KHZ 8 RX3 RX3 None Low 12 5KHZ 9 RX5 RX5 None Low 12 5KHZ 10 RX3 RX3 67HZ Low 25KHZ 11 RX3 RX3 254 1HZ Low 25KHZ 12 RX3 RX3 023 Low 25KHZ 13 RX3 RX3 754 Low 25KHZ 14 RX3 RX3 2 TONE Low 25KHZ 15 RX3 RX3 5 TONE Low 25KHZ 16 RX3 RX3 None Low 25KHZ 3
4. No part of this manual may be copied reproduced translated stored in a retrieval system distributed or transmitted in any form or by any means electronic or mechanical for any purpose without the express written permission of HYT 43
5. EEP_CLK AT25 AT24 EEPROM clock pin P57 RDY EEP ID 1 1M 0 512K EEPROM P56 ALE NC P55 HOLD NC For programming only Ground through 47K resistor P54 HLDA 2346 DIR Control the I O of data transmission H output control word L read data 41 P53 BLCK AF SCK O AK2346 SCLK 42 P52 RD NC O AK2346 TDATA MSK data output 43 P51 BHE AF_TDATA O pin For programming only Connect to VCC through 47K 44 P50 WR NC resistor PROG 5 14 780 Service Manual AK2346 DATA I O SDAT 45 P47 CS3 AF_DIO Output control word or read data Control power supply H supply power L soft power 46 P46 CS2 SBC O down Battery save control 47 P45 CS1 SAVE O H valid L battery save R5C Control power of receiver 48 P44 CS0 R5C O L off H valid T5C Control power of transmitter 49 P43 A19 T5C O L off H valid Control backlight 50 P42 A18 LED_EN O L off H valid 51 P41 A17 C5 Key 5 52 P40 A16 C6 I O Key 6 53 P37 A15 C1 1 54 6 14 C2 2 55 P35 A13 C3 I O Key 3 56 P34 A12 C4 4 Power on off detect 57 P33 A11 PWS soft power down L 58 P32 A10 DTMF_ACK O DTMF decode data read clock Accessory connection detect 59 P31 A9 OPT_SEL L yes 60 Vcc VCC VCC Wide band control H wide band path o
6. Waterproof ring expansion port RoHS 28 7102504000300 Machine screw M2 5 4 0mm RoHS 29 6201507000000 Cover expansion port RoHS 30 6100318000000 Waterproof ring RoHS 31 6300050000000 Aluminum chassis ADC12 RoHS 32 7500219000000 Motor RoHS 33 6201543000000 Sheet motor RoHS 34 1300007100020 TC 780 PCB 35 4100710100100 FFC 14Pin RoHS 36 1300007100030 Keyboard 37 7300028000000 Metal dome function key ROHS 38 6000198000020 Earpiece jack RoHS 39 7400128010100 Waterproof PC pad RoHS 40 41007101002 0 FPCB 20Pin RoHS 41 6000680000000 Battery latch RoHS 42 7000036000000 Spring RoHS 43 6000612000000 Front cover PC EXL9330 PMMA CP 61 RoHS 44 6100317000000 Numeric keypad RoHS oy BR Se gt ajaa N N a Sa S Sf Sf Se Sy Sm S N N Oe 38 780 Service Manual 39 HVT TC 780 Service Manual HVT TC 780 Service Manual C 780 VHF PCB View C 780 UHF PCB View C 780 VHF UHF PCB View C 780 Block Diagram C 780 VHF Schematic Diaqram C 780 UHF Schematic Diagram C 780 VHF UHF Schematic Diagram 41 HVT TC 780 Service Manual Specifications Freque
7. 36 HVT TC 780 Service Manual e N 6 TC 780 Parts List 2 No Material No Description Qty 1 6000135000000 PTT key cover RoHS 1 37 HVT TC 780 Service Manual 6100068000000 PTT key silica rubber ROHS 6100319000000 Emergency key silica rubber ROHS 7500210000000 Adhesive tape light guide 3M 9448 ROHS 6000609000000 Light guide RoHS 7400208000000 Felt speaker PES PBO US500PBO 40 0 RoHS 5001210000170 Speaker 200 1W 3W 90dB 40 H5 0mm RoHS 6201545000000 Fixing sheet speaker ROHS 9 7102003500200 Machine screw M2 0 3 5mm RoHS 10 7500230000000 Upper sponge LCD RoHS 11 5110000000410 LCD module RoHS 12 7102504000400 DB head screw screw 2 5 4 nut 2 0 3 ROHS 13 7102004021030 Self tapping screw ST1 9 4 0mm RoHS 14 4210015000000 FPC 4Pin 0 8T 30mm RoHS 15 5402001000010 Vibrating motor ROHS 16 4305030000050 E rotary switch RoHS 17 4302020000040 Volume switch RoHS 18 4100710200100 Side PTT keyboard RoHS 19 7500114000000 Cooler pad RoHS 20 4400000000000 SMA connector male 500 RoHS 21 6100316000000 O Ring RoHS 22 6000608000000 Rear cover PC EXL9330 RoHS 23 6100069000000 Waterproof ring volume control knob RoHS 24 7206004200000 Nut M6 0 4 2mm RoHS 25 6100322000000 Waterproof ring battery connector RoHS 26 5202003100150 Battery connector RoHS 27 6100290000000
8. Operations and Objectives Transmitter m Test Method Objective Item Condition Instrument 21 780 Service Manual Power in tuning Enter the adjustment Radio PTT up Adjust power to mode Power In mode and select an item Communication SK1 down 300 200mW tune The radio transmits Test Set or Adjust point 5 of wide TX TEST the Channel band Selector knob 1 255 Tx Low Power Enter the adjustment PTT up Adjust power to Tx L Power mode and select an item SK1 down 1W 0 2W Adjust point 5 of wide or band the Channel Selector knob 1 255 CDCSS Enter the adjustment 1 255 Make the demodulate Balance mode and select an item waveform on the radio DCS PII Adjust point 3 of wide communication test set band point 1 of medium to square waveform band and point 3 of narrow band CDCSS Enter the adjustment PTT up Adjust frequency Deviation mode and select an item SK1 down deviation to 750Hz DCS Dev Adjust point 3 of wide or 600Hz 400 2 for wide band point 1 of medium the Channel medium and narrow band and point 3 of Selector bands respectively narrow band Radio knob Communication 1 255 CTCSS Enter the adjustment Test Set PTT up Adjust frequency 67 0Hz mode and select an item TX TEST SK1 down deviation to 750Hz Low Frequency Adjust point 3 of wide HPF 20Hz or 600Hz 400 2 for wide Deviation band point 1 of med
9. and then release the keys to enter manual adjust mode 2 Adjustment Items 19 HVT TC 780 Service Manual The purpose of manual adjustment is to adjust Tx frequency deviation transmit power Rx sensitivity squelch and etc 1 SK2 Key Set the operating frequency Center frequency F3 is for one point adjustment F1 F3 and F5 are for three point adjustment and F1 through F5 are for five point adjustment Frequency switches from low to high in cycle 2 o Key Set channel bandwidth Value switches in the cycle of 25K gt 20K gt 12 5K The red LED glows once when 25K is selected 3 PTT SK1 or the Channel Selector knob Press the PTT to adjust up and press SK1 to adjust down You may also rotate the Channel Selector knob clockwise to adjust up or counter clockwise to adjust down Press the PTT to select a value for items BATT LOW SQL and VOX 4 Select an Adjustment Item After entering the adjustment mode the radio enters the first adjustment item Press A Y to select an adjustment item and save the adjustment value of the previous item When adjusting Tx items LED glows red when adjusting Rx items LED glows green 5 Save an Adjustment Value After adjustment is completed you need to press A Y to save the adjustment value and go to another adjustment item 6 Adjustment of Tuning Frequency Points Tuning frequencies are set through the programming software gt Five point Adjustment MHz TX TX1 TX2 TX3
10. item Adjust point 5 of Test Cable or adjusted to wide band Audio Test the Channel 119dBm Cable Selector knob SINAD212Db RX TEST 1 255 12dB Sensitivity RSSI Enter the adjustment HPF 300Hz Save Adjust the RF RSSI 12dB mode and select an LPF 3KHz level of the radio item Adjust point 1 of Audio Setting communication wide band and point 1 Frequency test set until the of narrow band 1kHz audio SINAD Frequency gets to12dB Deviation Press PTT to 3kHz save the current RSSI value AK2346 Rx Volume Enter the adjustment PTT up When the Adjust mode and select an Radio SK1 down volume is Rx Max Volume item Adjust point 1 of C or adjusted to the Communication wide band the Channel maximum level Test Cable Selector knob AC Level is 0 8 adjusted to oe 1 s 2W RX TEST 20 m b Sinql ms Sin HPF 300Hz n d dd inpu LPF 3KHz ALI Level of Load i 3 0V 0 2V while dual paths input 20ohms k e AC Level of 6V 0 2V 25 780 Service Manual SQL Value of Normal Enter the adjustment Radio Save Adjust the level Squelch Open mode and select an Communication to 120dBm and SqINorOpen item Adjust point 5 of Test Cable press PTT to wide band point 1 of Audio Test save medium band point 5 Cable of narrow band RX TEST HPF 300Hz LPF 3KHz SQL Value of Normal Enter the adjustment Save Adjust the level Squelch Close mode and select an to 122dB
11. the adjustment Test Set Save Adjust the frequency to bVox Gain mode and select an item TX TEST 1KHz and amplitude to Max Adjust point 1 of wide HPF 20Hz 6mv for modulation band LPF 15KHz signal and then press the PTT to save Tx High Power Enter the adjustment Radio PTT up Adjust power to 5W Tx H Power mode and select an item 4 SK1 down 4 7W 0 2W Adjust point 5 of wide Note band the Channel 5W TX TEST Selector UHF 4 7W knob 1 255 Tx Medium Enter the adjustment PTT up Adjust power to Power Tx mode and select an item Radio SK1 down 2 0 2W M Power Adjust point 5 of wide band Communication the Channel Test Set TX TEST Selector knob 1 255 Tx Low Battery Enter the adjustment Power Supply Save Adjust mode and select an item the Adjust point 1 of wide voltage band transmitting at high to 5 8V power and then press the PTT key to save Receiver 2 Test Method Objective Item Condition Instrument 24 780 Service Manual Bandpass Waveform Enter the adjustment mode and select the Rx Sensitivity item Adjust point 5 of wide band Scanner Bandpass Test Fixture PTT up SK1 down or the Channel Selector knob 1 255 Adjust the bandpas waveform to UHF VHF Rx Sensitivity Enter the adjustment Radio PTT up mode and select an Communication SK1 down When level
12. 84 P02 D2 PTT l H release L press B indicates the second AK2346 using the same clock with the first AK2346 for 85 P01 D1 AK2346B_DIR AK2346B register 5 Tone model B indicates the second AK2346 using the same clock with the first AK2346 for 86 0 AK2346B_DATA O AK2346B data 5 Tone model Reserved for patrol module 87 P107 AN7 NC Not used Determine option board according to different levels 88 P106 AN6 1 Used for future development 16 780 Service Manual 89 P105 AN5 VOX MIC signal input 90 P104 AN4 BATT BATT Battery level detect Battery identification 91 P103 AN3 BATTSEL Identify battery chemistry 92 P102 AN2 RSSI RSSI detect pin 93 P101 AN1 SQL Squelch level input A D conversion power grounded 94 AVSS GND input P100 ANO CTCSS signal input VREF A D conversion reference voltage AVCC A D conversion power input NC Reserved for patrol module Not used LCM_RST LCM 1 LCM_CD LCM_data command identification H data L command 17 HVT TC 780 Service Manual TC 780 VHF Parts List 1 Main Board Unit TC 780 UHF Parts List 1 Main Board Unit TC 780 VHF UHF Parts List 1 Keyboard Unit Adjustment Description Required Test Instruments 1 Radio communication test set 1 set 2 Scanner 1 set 3 3A 10V power supply 1 set 4 Digital voltmeter 1 s
13. Contents S a ama p 1 Radio OV6rViGeW coeno Ee pana ER EXE XR CER 2 Software 5 Circuit DescriptiOni iore aen d bb Suha c ete 6 CPU BINS eet eredi eere quce ce v eme decedere 13 TC 780 VHF Parts List 1 Main Board 18 780 Parts List 1 Main Board 18 TC 780 VHF UHF Parts List 1 Keyboard nennen 18 Adjustment Description teo Melee PD A de decre ee ead 18 Troubleshooting Flow Chart sse ren nnns 27 Disassembly and Assembly for 212 2 nennen eren 32 Exploded VIeW cte eot a a Meum UU AE 36 TGO2780 Parts List 23 5 eet e ec et ate reste tg v doeet 37 t tele ttum M redes tee 39 TOs 80 VHF PGB VIGW 3 5 SA S pedit ee e is dee de eio eene 41 TO Z80 UHF PGCB VIGW iioi ett etre e ee te fer e mi oerte lemen E edebat bes inns 41 TC 780 VHFE UHE PCB VIEW ciis ua eerte ue cr tun aaa Sak egeo udo uu 41 TC 780 Block Diagram e err rp e E Re ER pa Rn EET ne BR ee sna ER e loue ad 41 TC 780 VHF Schematic
14. HVT TC 780 Service Manual Programmable function key Channel Selector Knob Rotate the knob to select a desired channel Radio On Off Volume Control Knob Rotate the knob clockwise to turn the radio on and rotate the knob fully counter clockwise until a click is heard to turn the radio off Turn the knob clockwise to increase the volume or counter clockwise to decrease the volume LED Indicator The following table indicates LED mode and corresponding radio status Status LED Transmit Red Receive Green Low battery alert Flash red After transmitting a call within auto reset time Orange After receiving a call within auto reset time Flash orange slowly Missed call alert Flash orange rapidly Scan Flash green Accessory Jack The jack is used to connect audio accessories or other accessories such as programming cable HVT TC 780 Service Manual Software Specifications Specifications 256 Conventional Channels e 32 Channel Groups e 2 Tone DTMF HDC1200 HDC2400 Encode amp Decode e ATIS Encode Priority Channel Scan When the radio operates in talkaround mode the channel scan feature provides users with an easy way to monitor and join other channels a Revert Channel Press of the PTT during radio scanning shall cause the radio to transmit on the programmed revert channel b Nuisance Channel Delete To ensure accurate scanning press the Nuisance Channel Delete
15. adjust frequency deviation power level sensitivity squelch level and etc Note You must select Manual Adjust Mode 5 PC Adjust Mode from Optional Features Allows you to adjust the radio manually or automatically via PC in the programming software before you can enter manual Circuit Description Circuit Composition The overall circuit is composed of PLL VCO circuit transmit circuit receive circuit baseband processing 6 HVT TC 780 Service Manual circuit power supply circuit and MCU control circuit Frequency Configuration The receiver section utilizes double conversion The first IF is 44 85MHz and the second IF is 455 KHz The first local oscillator signal is supplied by PLL and VCO circuit The second local oscillator signal is generated from TCXO 44 395MHz The PLL and VCO circuit also generates the frequencies required by the transmit section 1 Receive Circuit Configuration of the receive circuit is shown in Figure 1 SPEAKER ar nm 7609 51 601 AF adjust Figure 1 Receive Circuit 2 RFAMP BPF The signal from antenna is amplified at RF amplifier Q410 after passing through a transmit receive switch circuit and a band pass filter The amplified signal is filtered by a band pass filter to eliminate unwanted signals before it goes to the first mixer 3 First Mixer The signal output by RF AMP BPF is mixed with the first local oscillator signal outpu
16. air bag do not place a radio in the area over an air bag or in the air bag deployment area Do not use any portable radio that has a damaged antenna If a damaged antenna comes into contact with your skin a minor burn can result Do not expose the radio to direct sunlight over a long time nor place it close to heating source If you wear a radio on your body when transmitting ensure that the radio and its antenna are at least 2 5cm away from your body 780 Service Manual LI mm 5 Microphone Speaker LCD Display Function Keypad LED Indicator 0 Jack 09 Battery Latch 46 Belt Clip PTT Push to Talk Key Press and hold down the PTT key to transmit release it to receive SK1 Side Key 1 HVT TC 780 Service Manual Programmable function key SK2 Side Key 2 Programmable function key LCD Display Used to display radio status information Function Keypad e Exit key Use the Exit key to return to the previous menu e Up key Down key e Menu Select key Used to enter the menu mode When you are in the menu mode this key is also used to make menu selections Exit Up Menu Select cf Call Back Down Redial Numeric Keypad Used to enter information for programming the radio s lists 212 uem Seer AoH 5 wo LITT TK Top Key
17. e2 Dev The radio transmits or 3 2 0 2KHz disable MSK MIC the Channel 2 5 0 2KHz DTMF CTCSS CDCSS Selector 1 8 0 2KHz for wide Adjust point 3 of wide knob medium and narrow band point 1 of medium Radio 1 255 bands respectively band and point 3 of Communication narrowband Test Set DTMF Deviation Enter the adjustment TX TEST PTT up Adjust frequency DTMF Dev mode and select an item HPF 20Hz SK1 down deviation to The radio transmits LPF 15KHz or 3 2 0 2KHz disable MSK MIC the Channel 2 5 0 2KHz 2 Tone CTCSS CDCSS Selector 1 8 0 2KHz for wide Adjust point 3 of wide knob medium and narrow band point 1 of medium 1 255 bands respectively band and point 3 of narrowband MSK Deviation Enter the adjustment PTT up Adjust frequency MSK Dev mode and select an item SK1 down deviation to The radio transmits or 2 5 0 2KHz disable DTMF MIC the Channel 2 0 0 2KHz 2 Tone CTCSS CDCSS Selector 1 6 0 2KHz for wide Adjust point 3 of wide knob 1 63 medium and narrow band point 1 of medium band and point 3 of narrowband bands respectively 23 780 Service Manual VOX GAIN1 Enter the adjustment Save Adjust the frequency to bVox Gain Min mode and select an item 1KHz and amplitude to Adjust point 1 of wide 10mv for modulation band Radio signal and then press Communication the PTT to save VOX GAIN10 Enter
18. et 5 3Aammeter 1 set Preparation 1 All Reset 1 Enter the Mode Turn on the radio while holding down and 5 1 and then release the keys to enter all reset mode 2 Select Frequency Band Press amp to select the corresponding frequency band and then press o 3 Select Reset Type 18 HVT TC 780 Service Manual Reset function Reset radioINFO Reset all data Press amp to select a reset type Press e to return to the previous menu or to confirm and enter the lower level menu When confirming initiation data the LCD displays as follows according to the three reset types Confirm Confirm Confirm Reset function Reset radioINFO Reset all data Press e to return to the previous menu or to confirm and enter data initiation process The radio displays Wirting data Please Wait 4 After reset is completed the radio displays Successful 2 VCO Measurement Adjustment Specifications Item Condition Test Termin Part Method Remarks Instrument al 1 Setting 1 Power supply 2 Tx VCO 1 CH Tx high Digital CV TC114 3 6V 0 1V 2 CH Tx low Voltmeter Check gt 0 5V Voltage VCO 3 Rx VCO 1 CH Rx high Adjusting 4 0V 0 1V Lock 2 CH Rx low Fixture Check gt 0 5V Voltage TC104 Adjustment Procedures 1 Procedures before Adjustment Turn on the radio while holding down SK2 and
19. g frequency data to PLL IC PLL IC is turned on to activate Tx VCO The outputted signal is amplified by Q703 Q124 and then divided by PLL IC step 2 5 KHz or 5 KHz 6 25 KHz The divided signal is compared with the reference signal from 16 8MHz crystal oscillator X101 frequency stability 2 5ppm in the phase comparator The frequency control voltage output from the phase comparator controls Tx VCO after passing through LPF In the meantime modulation signal Tx is passed to Tx VCO for frequency modulation The working principle in receive mode is similar to that in transmit mode HVT TC 780 Service Manual TX RX Figure 3 PLL Circuit Control Circuit The control circuit is comprised of MCU control circuit and power supply controller 1 MCU U605 MCU operates at 9 8304 MHz The CPU controls data transmission among receive circuit transmit circuit control circuit display circuit and peripheral circuit Eom aros a MCU PIT 4 DTMF CDCSS CTCSS B 7501 9 8304MHz Figure 4 Control Circuit 10 HVT TC 780 Service Manual 2 Power Supply Power supply of the radio is derived from the battery that supplies battery B after passing through fuse and then passes through power switch MCU controls power management IC U602 U603 and U604 to generate voltage including C5V 5CNS RSV T5V U604 AVR 1760 SAVE 5 5 5 AVR F601 0602 2541745 RSV Msv PD I AVR
20. ium LPF 3kHz the Channel medium and narrow CTCSS L Dev band and point 3 of Selector bands respectively narrow band knob 1 255 CTCSS Enter the adjustment PTT up Adjust frequency 136 5Hz mode and select an item SK1 down deviation to 750HzHz Medium Adjust point 3 of wide 600HzHz 400 2 for Frequency band point 1 of medium the Channel wide medium and Deviation band and point 3 of Selector narrow bands CTCSS M Dev narrow band knob respectively 1 255 22 780 Service Manual CTCSS Enter the adjustment PTT up Adjust frequency 254 1Hz mode and select an item SK1 down deviation to 750Hz High Frequency Adjust point 3 of wide or 600Hz 400 2 for wide Deviation band point 1 of medium the Channel medium and narrow CTCSS H Dev band and point 3 of Selector bands respectively narrow band knob 1 255 Tx Max Audio Enter the adjustment Radio PTT up Adjust frequency Deviation mode and select an item Communication SK1 down deviation to 4 0 2KHz Tx Max Dev Adjust point 3 of wide Test Set or 3 2 0 2KHz band point 1 of medium Audio Test the Channel 2 0 0 2KHz for wide band and point 3 of Cable Selector medium and narrow narrow band TX TEST knob 1 63 bands respectively HPF 20Hz LPF 15KHz Audio Signal 1 2 120mV 2 Tone Enter the adjustment PTT up Adjust frequency Deviation mode and select an item SK1 down deviation to Ton
21. key to temporarily remove the nuisance channel from the current scan list Busy Channel Lockout A channel already in use is not available to other users Programmable Function Buttons Six of the radio s buttons can be programmed as shortcut buttons for your most often used features Time out Timer The feature allows for more efficient use of channels by limiting the amount of time of each transmission The range is from 15 seconds to 600 seconds Emergency Press the Emergency key to emit emergency alarm or send ENI Emergency Number Identity background tone to a pre defined person or the dispatch center whichever is defined by the Emergency option Press the button again to cancel the emergency procedure e VOX Dual Home Channels Optional Functions a Man Down HVT TC 780 Service Manual b External Scrambler c Patrol Record d GPS Function Description 1 User Mode This mode is for normal operation by end users 2 All Reset Mode Allows you to initialize tuning items channel frequency and conventional functions See the Adjustment Description section for details 3 Clone Mode Factory Wired Clone Mode b Dealer Wired Clone Mode c Factory Wireless Clone Mode d Dealer Wireless Clone Mode Press SK1 and to enter clone mode press SK2 toggle between wired and wireless clone modes press TK to toggle between factory and dealer modes 4 Manual Adjust Mode Allows you to
22. level MCU works normally VCO 28 HVT TC 780 Service Manual VCO Check Power supply is Arial Replace Q306 Oscillator CV voltage in Rx is normal NO Replace Q102 Check if Q105 outputs Check Q105 normally Check if NO feedback is Check Q107 normal Check if 16 8MHz Oscillates NO Check power supply circuit Check CPU data circuit Transmit Circuit 29 HVT TC 780 Service Manual No output power Yes Power supply NO Check power works well supply circuit Yes The current is NO Control voltage is Check Q607 normal normal Check transistor 1 offset voltage amp a low pass network g Repair the I VCO transmission Drive stage is Troubleshooting network normal flow chart gt NO Check the The power is suited network normal Yes C Finished E Yes f the power is normal Finished NG E Replace Q404 Yes If the power is normal Dee NO Replace Q408 Receive Circuit 30 Yes Baseband NO IC outputs normally Yes Check volume switch and AF MUTE Control voltage PA MUTE is
23. m and SglNorSquelch item Adjust point 5 of press PTT to wide band point 1 of save medium band point 5 of narrow band SQL Value of Tight Enter the adjustment Save Adjust the level Squelch Open mode and select an to 117dBm and SqlTigOpen item Adjust point 5 of press PTT to wide band point 1 of save medium band point 5 of narrow band SQL Value of Tight Enter the adjustment Save Adjust the level Squelch Close mode and select an to 119dBm and SqlTigSquelch item Adjust point 5 of press PTT to wide band point 1 of save medium band point 5 of narrow band Rx Low Battery Enter the adjustment Save Adjust the mode and select an item Adjust point 1 of wide band voltage of power supply to 7 2N and press PTT to save Note Frequency deviation of receiver 3 KHz for wide band 2 5 KHz for medium band and 1 5 KHz for narrow band 26 HVT TC 780 Service Manual Troubleshooting Flow Chart MCU 27 HVT TC 780 Service Manual MCU Check Normal power on The RF circuit can t Check the alert tone control circuit No Speaker works well Replace the speaker 9 8304 MHz works normally ead and write available Reset No Check reading amp writing circuit Q610 works Normally Replace Q610 5 high
24. ncy Range General VHF 136 174MHz UHF 350 390MHz 400 470MHz 450 520MHz Channel Capacity 256 Channel Spacing 25 20 12 5KHz Operating Voltage 7 4 Battery 1700 Li lon Battery Life 5 5 90 duty cycle About 14 hours Operating Temperature 25 C 60 C Dimensions HxWxD 124x54x35mm with battery without antenna Weight with antenna amp battery 340g Receiver Sensitivity 0 25uV W 0 28uV N Selectivity 70 W 60dB N Intermodulation 65dB Spurious Response Rejection 70dB Rated Audio Power Output 1W Rated Audio Distortion lt 5 Frequency Stability 2 5 ppm Transmitter RF Power Output 5W 1W Spurious and Harmonics PPI 30dBm gt 1GHz Modulation Limiting 5 KHz W 2 5 KHz N FM Noise 45 40dB Modulation Distortion lt 3 Frequency Stability 2 5 ppm All specifications are tested according to TIA EIA 603 and subject to change without notice due to continuous development 42 HVT TC 780 Service Manual HYT endeavors to achieve the accuracy and completeness of this manual but no warranty of accuracy or reliability is given All the specifications and design are subject to change without prior notice due to continuous technology development Changes which may occur after publication are highlighted by Revision History contained in Service Manual
25. nd the APC circuit TX RX SW D403 D408 4 D406 D407 final 0401 0402 Figure 2 Transmit Circuit HVT TC 780 Service Manual 1 MIC Circuit and Modulation Circuit The audio signal from microphone is amplified by U204 after passing through the MIC control switch 0616 The resulting signal is then amplified pre emphasized and etc by 0203 Simultaneously DTMF 2 Tone 5 Tone signallings generated by the MCU are amplified by U203 and then mixed with MIC audio signal and finally fed to VCO for modulation 2 Driver and Final Stage Power Amplifier Circuit RF signal from local oscillator circuit is amplified by Q401 and Q402 The amplified signal is fed to the driver stage Q404 and then the final stage power amplifier Q409 for amplification The resulting signal then passes through LPF to filter harmonics before reaching the antenna for transmit 3 APC The automatic power control APC circuit stabilizes the transmit power by detecting the drain current of final stage amplifier Frequency Synthesizer PLL VCO circuit generates frequency for receiving the first local oscillator signal and transmitting signals PLL VCO circuit consists of Tx frequency oscillator Q103 Rx frequency oscillator Q101 buffer amplifier Q105 RF amplifier Q107 PLL IC U101 second harmonic circuit Q108 and Q109 and Tx Rx VCO control switch Q111 Q112 Q110 and Q102 In transmit mode IC120 transmits the operatin
26. normal NO Replace U609 Baseband IC inputs normally NO U403 outputs normally NO he second local oscillator is normal Yes Z402 voltage is normal Yes heck I input and PIN16 output Check Q410 path Yes Yes Yes NO NO NO NO TC 780 Service Manual Replace Q615 Replace AK2346 Check U201 Replace X401 Replace Z402 Check U403 Check VCO 31 HVT TC 780 Service Manual Disassembly and Assembly for Repair Disassemble the Radio Case 1 Remove the Radio On Off Volume Control knob and Channel Selector knob 2 2 Lift the chassis by its bottom and pull it out of the radio case 3 Figure 1 Disassemble the Speaker 1 After you separate the chassis from the case turn it for a certain degree then disassemble the FPC from the connector on the PCB Then remove the screw 4 on the speaker fixing ring and remove the speaker fixing sheet 2 Remove the speaker 6 and microphone 7 Note Take care not to damage the FPC connecting the speaker and the chassis 32 780 Service Manual Figure 2 Disassemble the Transmit and Receive Units 1 Screw out the waterproof ring the nut 9 and screws 110 locking the keypad PCB shown in figure 3 Figure 3 33 HVT TC 780 Service Manual 2 Rota
27. pen L wide 61 P30 A8 W_CON O band path closed 62 Vss GND GND Control audio power amplifier H 63 P27 A7 MUTE O on L off Narrow band control H narrow band path open L narrow band 64 P26 A6 N_CON O path closed Red light control 65 P25 A5 LEDR O H on L off Green light control 66 P24 A4 LEDG O H on L off 67 P23 A3 4 EN4 Channel Selector knob 4 Original EN2 68 P22 A2 EN3 EN3 Channel Selector knob 3 Original EN4 69 P21 A1 EN2 2 Channel Selector knob 2 Original EN3 70 P20 A0 EN1 EN1 Channel Selector knob 1 Original 1 15 780 Service Manual Control PLL pump current to improve phase lock speed 71 P17 INT5 PUMP_SW O H high current L low current Rise edge is generated when the 72 P16 INT4 DTMF_EST decode chip detects DTMF data 73 P15 INT3 MANDOWN down detect Audio path switch 74 P14 AF_MUTE O H on L off Motor control 75 P13 MOTO_CON H valid L stop PLL unlock detect 76 P12 PLL_UL H locked L unlocked PLL chip select output 77 11 PLL STB O H select L off MIC switch 78 P10 MIC_MUTE O H off L on 79 P07 D7 PTT_EXT External input 80 P06 D6 PLL_CLK O PLL clock output 81 P05 D5 PLL_DATA O PLL data output control 82 P04 D4 T R O H Rx L Tx Control transient H APC circuit works L APC 83 P03 D3 APC_SW O circuit is disabled PTT detect
28. t by PLL frequency synthesizer at the first mixer Q415 to create a 44 85 MHz first IF signal The first IF signal is then fed through a crystal filter XF401 to further remove spurious signals 4 IF Amplifier The first IF signal is amplified by Q412 and then enters U403 TA31136FN The signal is mixed with the 7 HVT TC 780 Service Manual second local oscillator signal 44 395MHz again to create a 455 KHz second IF signal which passes through a ceramic filter wide band 2404 narrowband 2403 to eliminate unwanted signals The resulting signal is detected by U403 to output audio signal from Pin 9 5 Audio Amplifier The Rx audio signal output by U403 is amplified by U201 and then passes through the audio processor U203 the received signalling is separated from the signal for decoding The amplified signal then is fed to AF MUTE volume switch SW601 volume control and Q615 PA MUTE control The resulting signal is finally fed to the audio amplifier U609 to output audio signal from speaker 6 Squelch Noise signal is derived from the Rx audio signal output by Pin 9 of U403 and is processed by U403 to produce an SQL level The SQL level is then compared in CPU U605 to generate a level which controls AF MUTE and PA MUTE It controls Q204 and Q615 to enable or disable the audio path Transmit Circuit The transmit circuit is composed of MIC circuit frequency synthesizer driver and final stage power amplifier circuit a
29. te the keypad PCB module Q3 for 180 degrees and then remove FPCQ2 from the connector on the PCB 13 merem Figure 4 3 Remove the five DB head screws 42 on the PCB screws 49 locking the the screw 40 locking the side PTT keyboard 4 Use an electric soldering iron to remove the two leads connecting motor from the PCB and then to unsolder the soldering tin at the antenna connector 5 Lift the PCB 4 and remove it from the chassis 34 HVT TC 780 Service Manual 14 ws D 15 EL 8 5 15 1809 8 DO 8 19 14 8 Figure 5 Precautions for Assembly Assemble the Radio Case and Chassis 1 Make sure the waterproof cushion surrounding the chassis is well fitted into the slot 1 of the chassis 2 Correctly position and assemble the speaker on the radio case Note Make sure that the speaker is fully assembled i the radio case 3 Fix the speaker sheet to the speaker and secure it with screw 3 4 Insert the top of the chassis into the radio case 4 Note Never have the speak magnetic core being pressed 5 Press the bottom of the the FPC chassis downwards to fit the chassis into the radio case Note If the chassis is assembled into the radio cag while the waterproof ring is in position use your fingers place it at the right position 35 HVT TC 780 Service Manual Figure 6 Exploded View
30. tor input pin 13 XIN XIN Connect to crystal oscillator 14 VCC VCC VCC PROG1 Connect to VCC through 47K 15 P85 NMI NMI NC resistor 16 P84 INT2 AF_TCLK AK2346MSK serial clock TCLK Programmable port used for future Used for future 17 P83 INT1 AUX1 O development development 18 P82 INTO AF_RDF AK2346MSK Rx detect RDF FD 19 P81 DTMF_SD DTMF decode data input Programmable port used for future Used for future 20 P80 AUX5 development development 21 P77 NC 22 P76 TA3O CTC_OUT O PWM output CTCSS CDCSS to 13 780 Service Manual VCO for modulation 23 P75 GPS_In GPS input PWM output CTCSS CDCSS to 24 P74 TA2O CTC_PLL O PLL for modulation Programmable port used for future Used for future 25 P73 AUX2 development development 26 P72 TA1O NC 27 P71 RxD2 TB5IN P70 TxD2 Accessory Port patrol record Accessory Port patrol record P67 TxD1 P66 RxD1 TXD1 Serial data output communicate with computer Serial data input communicate with computer PROG10 PROG4 P65 For programming only Ground through 47K resistor PROG3 P64 For programming only monitor output PROG2 P63 TxD0 Connect with option board Used for future development P62 RxD0 Connect with option board Used for future development P61 EEP SI AT25 EEPROM data input 24 EEPROM DATA input output P60
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