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Hytera Communications Co., Ltd Global Customer Service Center

TC508 Technical Training. Hytera Communications Co., Ltd Global Customer Service Center. Edited by Adam Sun 01MAR2012. Content. Function & Feature Technical Specification Software & Setting Disassembly & Re-assembly Circuit Description & Analysis Trouble Shooting.

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Hytera Communications Co., Ltd Global Customer Service Center

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  1. TC508 Technical Training Hytera Communications Co., Ltd Global Customer Service Center Edited by Adam Sun 01MAR2012
  2. Content Function & Feature Technical Specification Software & Setting Disassembly & Re-assembly Circuit Description & Analysis Trouble Shooting
  3. 1. Function & Feature Features The TC-508, one of the market-leading products in Hytera's commercial radio series, is an ideal choice for facilities, hospitality, manufacturing, retail, education and construction. As the affordable and reliable two-way radio for business and industry, TC-508 can largely enhance your productivity and management efficiency. The excellent design of HYT’s compact TC-508 portables guarantees superior ergonomics. Moreover, it can ensure a great performance in any operating conditions, thanks to MIL-STD 810 & Hytera's 5-year ALT test. Besides, TC-508 provides up to 14 hours of battery life to ensure long-lasting performance and convenience. Affordable price and distinct performance - TC-508 deserves your trust.
  4. 1. Function & Feature Radio Overview ④Antenna ⑤Channel Selector Knob ⑥Radio On-Off/Volume Control Knob ⑦Speaker ⑧Microphone ①PTT ②SK1 ③SK2
  5. 1. Function & Feature Main Functions High/Low Power Switch Monitor CTCSS/CDCSS and Tail eliminate Channel Scan Battery Save Low Battery Alert / Battery Strength Indicator Voice Operated Transmit (VOX) Busy Channel Lockout (BCL) Time-out-Timer (TOT) PC Programmable Wired Clone Selectable Carrier Squelch Level (2 levels: normal or tight)
  6. Content Function & Feature Technical Specification Software & Setting Disassembly & Re-assembly Circuit Description & Analysis Trouble Shooting
  7. 2. Technical Specification Testing Specifications
  8. 2. Technical Specification CV Testing and Adjust TC101 Notice RX and TX use the same VCO. When adjusting TC101, we need check TX and RX CV voltage at same time. CV Testing Point
  9. 2. Technical Specification Status Indication
  10. 2. Technical Specification Status Indication
  11. Content Function & Feature Technical Specification Software & Setting Disassembly & Re-assembly Circuit Description & Analysis Trouble Shooting
  12. 3. Software & Setting Programming Software Now, please open the programming software.
  13. 3. Software & Setting Software Adjustment Please do not tune these items if not repairing/testing necessary. We can enter Tuning Mode by Programming Software.
  14. Content Function & Feature Technical Specification Software & Setting Disassembly & Re-assembly Circuit Description & Analysis Trouble Shooting
  15. 4. Disassembly & Re-assembly Disassembly steps as following: Turn the radio off Remove antenna, channel selector knob, channel switch knob. (1,2,3) Remove the fixed screws. (4,5) Lift the chassis by its bottom and pull it out of the radio case. 2 3 4 1 5
  16. 4. Disassembly & Re-assembly Remove the fixed screws on the PCB and side PTT board Remove the antenna terminal with soldering Lift the PCB and remove it from the chassis. The Re-assembly method is similar and reverse the steps.
  17. Content Function & Feature Technical Specification Software & Setting Disassembly & Re-assembly Circuit Description & Analysis Trouble Shooting
  18. 5. Circuit Description & Analysis The Circuit including: The general circuit is composed of TX circuit, RX circuit, power supply circuit, control circuit and etc. RF parts: RX, TX FGU: PLL and VCO Control Circuit: power supply and CPU Baseband
  19. 5. Circuit Description & Analysis Block Diagram
  20. 5. Circuit Description & Analysis MCU Control, Signal Processing and Audio Power Amplification
  21. 5. Circuit Description & Analysis MCU Control, Signal Processing and Audio Power Amplification 1) MCU Control Circuit MCU control circuit is composed of MCU, EEPROM, and keys, etc. This section has the following functions: to initialize data of the radio and save data to EEPROM; to detect battery voltage and signals from external keys, LD and VOX, and to make response; to transmit required data to PLL based on the channel encoding status; to switch and control RX/TX based on the input PTT signal; to switch the squelch circuit on/off based on the input signaling decode signal and squelch level signal; to control circuits of high/low power switch, audio power amplifier, VCO power supply, RX power supply and TX power supply; (for programming) to communicate with PC via RXD/TXD based on the RS232 protocol, and transmit/receive data to/from PC. 2) Signal Processing Circuit a. TX Baseband Processing The audio signals input from MIC are divided into two parts. One part enters U601, and is then converted into digital signal by analog-to-digital conversion (ADC). Afterwards, the converted signal will go through a series of processing including low-pass filtering, AGC, companding, high-pass filtering, encrypting and pre-emphasizing, and then it will be output as baseband signal after digital-to-analog conversion (DAC). The baseband signal is processed by the active low-pass filter and then sent to VCO for modulation; for the other part, it will go through VOX circuit (Q611 and D616) and then sent to MCU for VOX processing.
  22. 5. Circuit Description & Analysis MCU Control, Signal Processing and Audio Power Amplification b. RX Baseband Process The demodulated IF signals with CTCSS/CDCSS signaling enter U601 for decoding. After analog-to-digital conversion, the IF signals will be converted into digital signals, which go to low-pass filter for filtering and then are divided into two parts. One part is processed by CTCSS/CDCSS decoder, and the other is processed by high-pass filter and then is subject to de-emphasis, decryption, signal expansion etc, and finally digital-to-analog conversion to output audio signal. 3) Audio Power Amplifier The audio signal output from U601 is amplified by the audio power amplifier (U302) to drive the speaker directly.
  23. 5. Circuit Description & Analysis MCU&Power
  24. 5. Circuit Description & Analysis MCU&Power
  25. 5. Circuit Description & Analysis AF AMP and Speaker/MIC interface
  26. 5. Circuit Description & Analysis Power supply The 7.4V battery voltage is converted to 5V via DC-DC module U604, and further converted via LDO U602 to 3V including two channels: VCC and VDD. VCC powers CPU and VDD powers PLL circuit. The 5V voltage will be converted via LDO U606 to 4.5V including two channels: VT and V-SAVE. V-SAVE powers VCO circuit and VT powers TX circuit. Finally, V-SAVE controlled by Q604 and Q305 outputs VR, which supplies RX circuit.
  27. 5. Circuit Description & Analysis Power supply
  28. 5. Circuit Description & Analysis PLL&VCO PLL Frequency Synthesizer The PLL circuit mainly provides the first local oscillator signal (for RX) and RF carrier signal (for TX). It is composed of VCO and PLL chip, allowing frequency tracking and channel switching under the control of MCU signals.
  29. 5. Circuit Description & Analysis PLL&VCO 1) PLL The step frequency of PLL circuit is 5 KHz or 6.25 KHz. In U101, the 38.4MHz reference oscillator signal is divided into 5 KHz or 6.25 KHz reference frequency via a fixed counter in PLL. The signal from VCO enters the PLL after processed by the buffer amplifier, and then it is applied to the variable frequency divider in PLL for division. After division, the signal is compared with the reference frequency at the phase detector (PD) in PLL. The signal from the PD passes through a low-pass filter and then is applied to the varactors (D101 and D102) of VCO to control the output frequency. Then the RF signal is processed by the buffer amplifiers (Q104 and Q406), and controlled by D404 and D405 to only serve as TX signal or RX first local oscillator signal. 2) VCO The VCO section is realized by the three-point capacitor oscillator circuit. TX VCO and RX VCO share the same oscillator circuit. Q103 controls the switch between TX VCO and RX VCO. Note: If the PLL is unlocked, the LD pin of U101 outputs low level. If the microprocessor detects such situation, TX/RX operation is prohibited, and an alarm sounds.
  30. 5. Circuit Description & Analysis PLL&RX
  31. 5. Circuit Description & Analysis PLL and 38.4MHz Ref. Crystal
  32. 5. Circuit Description & Analysis TX&VCO
  33. 5. Circuit Description & Analysis VCO
  34. 5. Circuit Description & Analysis TX The audio signal from MIC is sent to the MCU chip (U601) directly. The baseband signal processing circuit in U601 converts the amplified audio signal to digital signal via A/D conversion, and then converts the digital signal to analog audio signal via D/A conversion after all processing procedures such as filtering, signal compression, encryption, pre-emphasis, TX gain control and amplitude limiting are completed. Then the analog audio signal from MCU passes through the low-pass filter circuit and directly goes to VCO for frequency modulation. The modulated HF carrier signal passes through the buffer amplifiers (Q104 and Q406), and goes to the amplifier (Q401) through the RF switch (D404). Then the amplified RF signal enters the low-pass filter circuit after it is further amplified by the pre-driver (Q402) and final-stage power amplifier (Q403), and then it will be finally transmitted via antenna after ultra harmonics is removed.
  35. 5. Circuit Description & Analysis TX
  36. 5. Circuit Description & Analysis RF power amplifier The modulated carrier signal from VCO is pre-amplified at Q104 and Q406, and controlled at D404 and D405. Then it is amplified by the front-stage amplifier Q401, the pre-driver Q402 and the final-stage amplifier Q403 orderly. Finally it goes to the LC low-pass filter (LPF) and is transmitted from the antenna after high-order harmonics are removed by LPF. APC circuit is composed of Q404, Q405 and U401. U401 controls the bias voltage at the gates of Q402 and Q403, to control TX current and to further regulate power.
  37. 5. Circuit Description & Analysis TX/RX switch and RF LPF
  38. 5. Circuit Description & Analysis RF AMP and TX final AMP
  39. 5. Circuit Description & Analysis Current detect and APC
  40. 5. Circuit Description & Analysis RX After the RF signals are received from the antenna, the undesired out-of-band signals are filtered out at the bandpass filter. Then the remaining RF signals are amplified by LNA Q501. Afterwards, the amplified signal goes through the bandpass filter again to eliminate undesired out-of-band interference signal. After being filtered and amplified, the RF signals and first LO signals are mixed at Q502, and then the mixed signal is filtered by crystal filter XF501 to get 38.85MHz differential signals as the first IF signal. After being amplified by Q506, the IF signal goes to chip U611, where the signal will be mixed with the second LO signal (38.4MHZ). Next, the signals will be filtered by CF501 to produce 450KHz IF signal. When the IF signals are processed by demodulation circuit (including U611 and CD501) to generate audio signals, which are delivered to IC Q613 for amplification and output in two channels. After simple filtering, one channel of signals is sent to MCU U601 for CTCSS/CDCSS decoding; for the other channel, it goes through two stages of low-pass filter first, and then it goes to high-pass filter U610 (consisting of four operational amplifiers) for audio processing. Finally, the signals will be sent to audio power amplifier U302 for amplification so as to drive the speaker.
  41. 5. Circuit Description & Analysis RX
  42. 5. Circuit Description & Analysis RX LNA and BPF
  43. 5. Circuit Description & Analysis Mixer and IF filtering and amplifier
  44. 5. Circuit Description & Analysis IF processing IC, noise selecting freq. and AF HPF
  45. 5. Circuit Description & Analysis Level Diagram
  46. Content Function & Feature Technical Specification Software & Setting Disassembly & Re-assembly Circuit Description & Analysis Trouble Shooting
  47. 6. Trouble Shooting PCB Top Side Antenna Soldering Point AF AMP TDA2822 APCCircuit MIC CPU Memory 24C16 32.768KHZ Crystal
  48. 6. Trouble Shooting PCB Bottom Side Channel switch Volume Switch PTT board SPK socket Battery connector MIC socket Power management IC Power AMP RQ0002 38.85MHZCrystal Filter VCO PLL IC MB15E03SL 50C24 450 Audio process IC 2902 IF IC:4116
  49. 6. Trouble Shooting PCB Key Testing Point External power supply connection point ANT test point PTTtest point BPFtest point CV test point LDchecking point
  50. 6. Trouble Shooting Can not power on Voice abnormal TX problem RX problem Unlock
  51. 6. Trouble Shooting 1. Can’t Power On Description: After connecting 7.4V DC voltage, the radio has not any response. Analysis: Check power supply circuit and control circuit. Checking Steps: Battery connector is connected well with main radio Power switch The pin 1 of Regulator IC U604 output is 5V or not U602 output is 3V or not CPU power on crystal 32.768KHz CPU pins is false soldering or broken
  52. 6. Trouble Shooting 1. Can’t Power On U604 U606
  53. 6. Trouble Shooting 2. Voice Abnormal (no voice when power on; abnormal voice) Description No voice or abnormal voice when power on the radio Analysis AF output circuit is composed of volume switch S201, AF amplifier U302 and power supply tube Q303, speaker socket and speaker. Checking Steps Speaker, speaker line’s soldering Speaker socket is connected well or not Volume switch AF amplifier IC U302 TDA2822 is working well or not. Q303 (717) is damaged or not.
  54. 6. Trouble Shooting 3. TX Problem (No TX power or low power) RD07 Description After power on, press PTT, LED is red, but no TX power output or it is low. Analysis Check RF AMP and APC circuit. Test TX power supply, Q611/5T, U430/APC, and test TX power by communication analyzer to judge which stage has problem. Checking Steps 6pin of U606 output voltage is 4.5V or not Check TX current, High power is about 1.6A, and 0.8A Low Power. If normal, that means APC circuit has no problem, generally, the power amplifier Q403 (RD07) is burnt. Check the positive pole of C420 in APC circuit has about 3.5V voltage output, or not Check the bias voltage of final power amplifier is normal or not Check driver amplifier and final power amplifier RD07 is damaged or not Test the input pin’s voltage of Q403 is 3-5V while pressing PTT. If not, check the APC circuit. U606 APC C420
  55. 6. Trouble Shooting 4. RX Problem (Low RX or No RX) Description After power on, TX is normal, but, no RX(green led is not on) or RX sensitivity is low. Analysis Check RX filtering circuit or IF processing circuit. Checking Steps VHF/UHF RX sensitivity is 0.25/0.28µV. We use signal injection to check which stage has problem. The important is IF AMP and LNA/Mixing circuit. The first IF is 38.85MHz, the 2nd IF is 450kHz. Check the carrier squelch level, and CTCSS setting. The output voltage of Q604 is 5V or not Mixer Q502 is damaged or not 450kHz filter is loose or damaged or not 38.85MHz filter is normal or not IF processing IC U611 is false soldered or damaged Demodulator is loose or damaged or not
  56. 6. Trouble Shooting 5. Unlock Description After power on, the radio sounds “Dudu…”. And it can’t transmit or receive signal. Analysis: check RX/TX common circuit and PLL circuit. Checking Steps: Power supply of PLL is 3V or not CV voltage is normal or not 86pin of CPU is normal or not (H:Lock, L:Unlock) 38.4MHz crystal is normal or not IC U101 PLL part is false soldering or damaged
  57. THANKS Please call or email Hytera Global Customer Service Center, if you have any question about Hytera Product. Service Direct Line: +86-755-86137081 Email: overseas.service@hytera.com Website: www.hytera.com
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