HYT TC-610 User manual

TC-610/620 Service Manual
1
Contents
General--------------------------------------------------------------------------------------------2
Radio Overview---------------------------------------------------------------------------------3
Programmable Functions-------------------------------------------------------------------------7
Software Specifications-------------------------------------------------------------------------8
Circuit Description-------------------------------------------------------------------------------12
CPU Pins--------------------------------------------------------------------------------------20
TC-610/620 VHF Parts List 1----------------------------------------------------------------------23
TC-610/620 UHF Parts List 1---------------------------------------------------------------------38
Adjustment Description-------------------------------------------------------------------------59
Troubleshooting Flow Chart--------------------------------------------------------------69
Disassembly and Assembly for Repair------------------------------------------------------72
Exploded View----------------------------------------------------------------------------------75
TC-610/620 VHF/UHF Parts List 2------------------------------------------------------------------77
Packing------------------------------------------------------------------------------------------79
TC-610/620 VHF PCB View------------------------------------------------------------------------80
TC-610/620 UHF PCB View-----------------------------------------------------------------------82
TC-610/620 VHF/UHF Level Diagram-----------------------------------------------------------84
TC-610/620 VHF Block Diagram----------------------------------------------------------------85
TC-610/620 UHF Block Diagram-----------------------------------------------------------------86
TC-610/620 VHF Schematic Diagram-----------------------------------------------------------87
TC-610/620 UHF Schematic Diagram-----------------------------------------------------------90
Specifications--------------------------------------------------------------------------------93

TC-610/620 Service Manual
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General
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.
User Safety 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.
Do not transmit until all RF connectors are verified secure and any open connectors are properly
terminated.
Use only HYT original batteries and chargers.
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 an 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.

TC-610/620 Service Manual
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Radio Overview
TC-610
①PTT(Push-to-Talk)
Key
②SK1(programmable
key)
③SK2(programmable
key) ④Speaker
⑤Microphone ⑥Antenna ⑦LED Indicator ⑧Channel
Selector Knob
⑨Radio On-Off/Volume
Control Knob ⑩Battery Latch ⑪Accessory Jack and Programming Port ⑫Accessory Cover
⑬Belt Clip ⑭Battery ⑮Screw, Belt Clip ⑯Charging Piece

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TC-620
①PTT(Push-to-Talk)
Key
②SK1 (programmable
key)
③SK2(programmable
key) ④Speaker
⑤Microphone ⑥Antenna ⑦LED Indicator ⑧Channel
Selector Knob
⑨Radio On-Off/Volume
Control Knob ⑩Battery Latch ⑪Accessory Jack and Programming Port
⑫Accessory
Cover
⑬Belt Clip ⑭Battery ⑮Screw, Belt Clip ⑯Charging Piece

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(1) PTT (Push-to-Talk) Key
Used to switch between transmit and receive modes. Hold down the PTT key and speak into the
microphone to transmit, and release it to receive.
(2) SK1 Key
Side key 1, programmable. Your dealer can assign one function to the key via the programming
software.
(3) SK2 Key
Side key 2, programmable. Your dealer can assign one function to the key via the programming
software.
(4) Speaker
(5) Microphone
(6) Antenna
(7) LED Indicator
Status
LED Indication and Alert Tone
User Wired
Clone
Source Radio: Power on the
radio while holding down the
SK2 key.
Target Radio: Rotate the
Radio On-Off knob clockwise
to turn the radio on.
The LED flashes orange once.
Source Radio: Power on the
target radio and connect the
cloning cable. Then press
the SK2 key on the source
radio to initiate cloning.
1. The LED flashes red when cloning is in progress.
2. The red LED goes out when cloning is completed.
3. The red LED goes out when cloning fails.
Target Radio 1. The LED flashes green when cloning is in progress.
2. The green LED goes out when cloning is completed.
Power On
1. The power-on alert tone is heard when the radio is
powered on.
2. When the current channel is idle, beeps are heard.
Low Battery Alert The LED flashes red and the low pitched tone is heard
every ten seconds.
Transmitting
1. Red LED.
2. When transmission times out, beeps are heard.
3. TOT Pre-alert: One beep is heard.
Receiving The LED glows green when carrier presents.

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Scanning
1. The LED flashes green every 1 second when
detecting.
2. Scan Start Tone (programmable by your dealer):
One beep is heard.
3. Scan Stop Tone (programmable by your dealer):
One beep is heard.
4. Priority Channel Scan Tone (programmable by your
deader): If the radio stays on a priority channel to
receive, one beep will be heard.
Programming Reading: The LED flashes red.
Writing: The LED flashes green.
Power Adjust From High to Low Power: The low pitched tone is heard
.
From Low to High Power: The high pitched tone is heard
VOX Enable VOX: The high pitched tone is heard.
Disable VOX:The low pitched tone is heard.
(8) Channel Selector Knob
Rotate the knob to select a desired channel among channels 1 to 16.
(9) 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.
(10) Battery Latch
(11) Accessory Jack & Programming Port
(12) Accessory Cover
(13) Belt Clip
(14) Battery
(15) Screw, Belt Clip
(16) Charging Piece

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Programmable Functions
The SK1/SK2 key can be assigned with one of the following auxiliary functions by your dealer.
None
Monitor
Monitor Momentary
Scan
Squelch Off
Squelch Off Momentary
Power Adjust
Battery Power Indication
VOX
The following functions are programmed by default at factory:
Key Operation TC-610 TC-620
SK1 Short Press None None
Long Press Battery Power Indication Battery Power Indication
SK2 Short Press None None
Long Press Squelch Off Momentary Squelch Off Momentary
Note:
Short Press: A key is held down for less than 1.5s.
Long Press: A key is held down for 1.5s at least.

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Software Specifications
Function Description
1. Available Channels: 1 to 16 channels
2. Channel Spacing: 25KHz/12.5KHz
3. Channel Step: scan channels in steps of 5/6.25/10/12.5KHz
4. Tx/Rx Indication (red/green LED)
5. CTCSS/CDCSS Encode & Decode (CTCSS: 38 groups; CDCSS: 83 groups; the CTCSS squelch
tail reverse method is selectable at 180/120 degrees.)
6. Low Battery Alert
7. Auto Battery Save
8. Unlock Detect and Alarm
9. Selectable Squelch Level (0-9)
10. Monitor
11. Time-Out Timer (TOT)
12. Squelch Tail Elimination
13. PC Programming (including PC manual adjustment and PC auto adjustment)
14. High/Low Power Select (2.0/5.0W)
15. Wide/Narrow Band Compatibility
16. Busy Channel Lockout
17. Wired Clone
18. Battery Power Indication
19. Manual Adjustment
20. VOX and Selectable Sensitivity Level (1-5)
Radio Modes
User Mode
User Mode is for conventional communication operations. Turn on the power, and the radio enters User
Mode directly.
PC Programming Mode
In User Mode, the PC programming software triggers PC Programming Mode by communication via a
special communication protocol. In this mode, functions can be set and parameters can be adjusted via
the PC programming software (including user version and factory version).
Wired Clone Mode
Description
Wired Clone Mode is a separate mode. To enter other modes, the radio must be turned off and back on.
Wired Clone Mode is classified into User Wired Clone Mode and Factory Wired Clone Mode.

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1. User Wired Clone Mode
Connect the two radios with the cloning cable. Power on the source radio while holding down the SK2
key on it. The radio enters Wired Clone Mode in two seconds. Rotate the Radio On-Off knob clockwise
to power on the target radio, and the radio enters User Mode. This mode clones the parameter data in
EEPROM of the source radio into that of the target radio. The transferred data only includes channel
data and shared parameters, excluding adjustment data, information of model version, serial number,
etc.
2. Factory Wired Clone Mode
Short out the SELF pin of the source radio’s MCU and connect the two radios with the cloning cable.
Power on the source radio while holding down the SK2 key on it. The radio enters Wired Clone Mode in
two seconds. Rotate the Radio On-Off knob clockwise to power on the target radio, and the radio enters
User Mode. The transferred data includes all data in EEPROM except the serial number, and the switch
icon of Manual Adjustment Inhibit.
Process
Wired Clone
1. The LED flashes orange once when the source radio enters Wired Clone Mode. Press the SK2 key
again to copy data into the target radio.
2. During cloning, the LED of the source radio flashes red, while the LED of the target radio flashes
green. When cloning is completed, the red LED of the source radio and green LED of the target
radio go out, preparing for the next cloning.
3. During cloning, if an abnormal situation occurs, cloning will be terminated. The red LED of the
source radio goes out, preparing for the next cloning.
4. When cloning is completed, the source radio returns to the preparing status. Press the SK2 key to
clone again.
Manual Adjustment Mode
Power on the radio while holding down the PTT key and SK2 key. The radio enters Manual Adjustment
Mode.
Note: The operation is controlled by the switch of Manual Adjustment Inhibit in the programming
software. When the adjustment function is disabled, the radio can not enter this mode. This can prevent
radio users’accidental entry and parameter changes, which will affect the performances of the radio.
During production, disable the adjustment switch, to prevent radio users from accidentally entering and
changing adjustment values after the values are adjusted. The adjustment values can only be reset in
the factory set mode and are adjusted again according to the requirements. They can not be changed in
any other mode.
Adjustment Description
1. Enter Manual Adjustment Mode
Hold down the PTT key and SK2 key simultaneously for 2s at least to power on the radio. The orange
LED (red LED + green LED) lights, indicating the entry into the adjustment mode. Release the keys to

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enter item N (N is dependent on the position of the Channel Selector knob) of Tx Adjustment Items in the
adjustment mode. The radio stays at Tx Adjustment Items by default and the LED glows red.
Note: The adjustment item CH15 is invalid, while CH16 is used to toggle between Tx Adjustment Items
and Rx Adjustment Items. If the Channel Selector knob locates at CH15 or CH16, the LED glows neither
red nor green.
2. Switch between Tx Adjustment Items and Rx Adjustment Items
Rotate the Channel Selector knob to CH16. Hold down the PTT key for 1.5s at least to toggle between
Tx Adjustment Items and Rx Adjustment Items. If the LED lights red upon key press, the radio switches
to Tx Adjustment Items. If the LED lights green upon key press, the radio switches to Rx Adjustment
Items.
The LED glows red for Tx Adjustment Items.
The LED glows green for Rx Adjustment Items.
3. Switch among Tx/Rx Adjustment Items
Switch via the Channel Selector knob.
Tx: CH1-CH14 indicate Tx preset power, Tx low power, Tx medium power, Tx high power, CDCSS
deviation, CTCSS deviation (low), CTCSS deviation (medium), CTCSS deviation (high), VOX 1, VOX 2,
VOX 3, VOX 4, VOX 5 and Tx low voltage threshold respectively.
Note: The Tx medium power of TC-610/620 is not required to be adjusted. Please skip this item.
The LED glows red for adjustment items CH1-CH14.
CH15 is invalid and the red LED goes out.
Rx: CH1-CH8 indicate SQL ON 1, SQL ON 5, SQL ON 9, SQL OFF 1, SQL OFF 5, SQL OFF 9, Rx low
voltage threshold and Rx bandpass filter respectively.
The LED glows green for adjustment items CH1-CH8.
CH9-CH15 are invalid and the green LED goes out.
4. Wide/Narrow Band Switch in an Adjustment Item
In an adjustment item, hold down the PTT key for 1.5s at least. The LED flashes orange, indicating the
long key press is valid. Release the key and the radio switches between wide band and narrow band
cyclically. After the wide/narrow band switch, the adjustment point is regarded as the first frequency of
the current band by default.
5. Frequency Switch in a Band of an Adjustment Item
In a band of an adjustment item, hold down the PTT key for less than 1.5s. The LED flashes orange,
indicating the short key press is valid. The radio switches frequencies one after another.
6. Plus-Minus of the Adjustment Value in a Band of an Adjustment Item
In a band of an adjustment item, short press SK1, and the adjustment value increases in steps of 1. Hold
down SK1, and the adjustment value increases continuously in steps of 1. When the adjustment value
gets to the maximum value allowed by the adjustment item, the adjustment value will remain at the
maximum value.
In a band of an adjustment item, short press SK2, and the adjustment value decreases in steps of 1.
Hold down SK1, and the adjustment value decreases continuously in steps of 1. When the adjustment

TC-610/620 Service Manual
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value gets to the minimum value allowed by the adjustment item, the adjustment value will remain at the
minimum value.
7. Process on Several Special Items
Tx: CH9-CH14 indicate VOX 1, VOX 2, VOX 3, VOX 4, VOX 5 and Tx low voltage threshold respectively,
which are related with the AD sampling. After the above adjustment items are entered, press SK1 or SK2
to start the AD sampling (including calculation process) once. Rotate the Channel Selector knob to save
the current AD sampling value. If SK1 or SK2 is not pressed, the AD sampling will not be started and the
previous adjustment values can not be updated.
Rx: CH1-CH8 indicate SQL ON 1, SQL ON 5, SQL ON 9, SQL OFF 1, SQL OFF 5, SQL OFF 9 and Rx
low voltage threshold respectively, which are related with the AD sampling. After the above adjustment
items are entered, press SK1 or SK2 to start the AD sampling (including calculation process) once.
Rotate the Channel Selector knob to save the current AD sampling value. If SK1 or SK2 is not pressed,
the AD sampling will not be started and the previous adjustment values can not be updated.
8. Key Description
Short Press: A key is held down for less than 1.5s.
Long Press: A key is held down for 1.5s at least.

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Circuit Description
Realization Methods for Basic Functional Modules
PLL Frequency Synthesizer
The PLL circuit mainly generates the local oscillator signal for reception and the RF carrier signal for
transmission. It consists of the VCO oscillator circuit and baseband processor and enables frequency
tracking and channel change under the control of MCU signal.
1. PLL
MB95F108AK
WPFV-GE1
U605
1/2
17bitDIV
32/33
OSC
1/2
21bitDIV
U202
CP
RX-VCO
L102
D103
L101
APC/TUNE
T/R-SW
CLK
DATA
EN
Q101
2SK508NV
D102
BUFFER
Q6
1
23
D104
D101
D100
Q100
2SK508NV
12.8MHZ
TX-VCO
LPF
Q5 1
23
Figure 2
The step frequency of the PLL circuit is 5.0KHz, 6.25KHz, 10.0KHz or 12.5KHz. Therefore, the
reference oscillator signal (38.4MHz) is divided into 5.0KHz, 6.25KHz, 10.0KHz or 12.5KHz reference
frequency by a fixed counter at U202 in PLL. The output signal from VCO passes through buffer Q102
followed by amplifier Q103 and enters U202 in PLL for frequency division by a variable divider. The
signal derived from the frequency division is compared with the reference frequency at the phase
comparator PD in PLL. Then the output signal from the phase comparator is filtered by a low-pass filter
and passed to varactors D100, D101, D102 and D103 of VCO, to control the output frequency.
2. VCO
The VCO section is realized by the oscillator circuit of three-point capacitance.
The oscillator frequency of VCO is generated by Q100 in transmit mode and by Q101 in receive mode.
U202 generates a control voltage via the phase comparator to control varactors (D100 and D101 in
transmit mode; D102 and D103 in receive mode), so that the oscillator frequency of VCO is made
consistent with the preset frequency in MCU within a broader frequency range.
Transistor Q652 toggles between transmit and receive modes under the control of T/R. In transmit mode,
T/R is set to low level, causing Q653 to be on and Q100 to operate. In receive mode, T/R is set to high

TC-610/620 Service Manual
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level, causing Q653 to be off and Q101 to operate. The output from Q100 and Q101 is amplified by
Q102 and sent to the buffer amplifier for process.
If PLL is unlocked, the LD pin of U202 outputs low level. When this situation is detected by the
microprocessor, transmit/receive operations are inhibited and a warning tone is heard.
RF Power Amplifier Circuit (Tx Section)
Diagram for RF Power Amplifier Circuit
R/TSW
L453
1u
RX
RQA0002
2
13
3 Amplifier
Q401
2SC4988
1
23
APC
LPF
2SK3475
2
13
Q400
2SC5108
1
23
Q104
2SC5108
1
23
MATCH
ANTENNA
Q402
0
RF PA
Q403
Figure 3
To obtain the required RF power, the output RF signal from VCO is amplified by driver amplifiers Q400
and Q401 after passing through buffer Q104. The amplified RF signal enters driver Q402, which
performs power pre-amplification on the input signal, to derive a certain power to drive the final-stage
power amplifier. Then the final-stage power amplifier Q403 performs power amplification again on the
input RF signal to derive the required power. Finally, the amplified RF signal passes through Tx-Rx
switching diode D401 followed by the LC low-pass filter circuit (LPF). The signal is transmitted through
the antenna after ultraharmonic is removed by the LPF.
Rx Amplifier and Mixer Circuit (Rx Section)
1. Rx Amplifier (LNA) and RF Bandpass Network (BPF)
To obtain better frequency band selectivity, the Rx bandpass utilizes multi-level electrically tunable circuit.
The diagram is shown below:
C505
LNA
TUNE BPF
TUNE FROM MCU
C504
C523
L508 L506
Q500
D503
L507
D506
1
23
L501
C526
C519
C524
L502
C521
C506
TUNE FROM MCU
D504
D505
D507
TUNE BPF
Figure 4
The Rx signal input from the antenna is filtered to remove the out-of-band signal at the electrically
tunable bandpass network (D503, D504, L501, L502, C503, C505 and 507) and then amplified by
low-noise amplifier (LNA) Q500 to obtain a certain level required for receiving. The signal passes
through the three-level bandpass network (mainly consisting of D505, D506, D507 and periphery
components) to effectively restrain the out-of-band interference and to derive pure Rx RF signal, which

TC-610/620 Service Manual
14
will be fed to the mixer stage.
MCU provides the electrically tunable control signal, the required level of which can be obtained through
table looking up or formula computing, to accurately control varactors to operate within proper voltage
range. The control signal forms a bandpass filter with the periphery inductors and capacitors and tracks
Rx frequency according to the change of MCU control voltage, to meet the requirements of preset Rx
sensitivity and out-of-band rejection.
2. Mixer Circuit (MIXER) and IF Bandpass Network (BPF)
Diagram for Mixer Circuit
L53022nH
C533
C534 C532
C531
XF1
Q501
38.85MHZ
1stIF BPF
RF MIXER
AN29160
C528
Figure 5
The mixer circuit mainly processes the local oscillator signal and Rx RF signal output by VCO. The first
IF from the mixer circuit is used by the demodulator to discriminate frequency. Here the active mixer is
utilized.
The mixer transistor (Q501) utilizes dual gate MOS FET (3SK318) and has better noise characteristics
and square law characteristics. The isolation between the local oscillator signal and the Rx signal is high.
To ensure proper sensitivity, the mixer transistor should have a certain gain, which can be tuned
delicately via offset.
The output signal from the mixer circuit passes through inductor L509 to remove residual spurious and
then enters the first IF filter, which utilizes the first-class crystal filter to ensure sufficient bandwidth and
excellent selectivity. The signal finally enters baseband processor AN29160 for demodulation.
APC/TUNE Automatic Power Control Circuit
Diagram for the Circuit:
R430
R421 Q431
DTA114YE
R437
C441
R422
R441
R433
R434
from MCU
V_BAT
TX_VCC
R432
R440
C435C437
R438
C436
R442
C438
-+
+-
U430
NJM2904
1
3
4
2
5
7
8
6
R436
Q430
DTC114EE
2
31
R431
R420
R439
R500
C440C439
to RF PA(APC)
C434
R435
to BPF(TUNE)
Figure 6

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15
According to the selected channel, MCU outputs the corresponding PWM waveform, which is reshaped
by the RC filter network (R441, R442, C440 and C441) to derive the level for the APC/TUNE control
signal. One part is used as the control voltage of the Rx electrically tunable circuit after passing through
R500. In transmit mode, the level is voltage-divided by R439 and R440 to obtain the APC reference
voltage.
The transmit current passes through R420, R421 and R422 to derive the error detect voltage. The
voltage is amplified by operational amplifier U430 and then compared with the APC reference voltage to
output the APC control voltage and to form control power of closed-loop negative feedback when the
transmit current changes.
Audio and Signalling Process Circuit
Baseband processor AN29160 has high integration level and powerful functions. Many of the process
functions (as VCO level detect & output, SQ signal level detect & output, Tx-Rx audio process switch,
audio amplifier, etc) can be realized inside and can be used in both receive and transmit modes.
1. Diagram for Tx Audio & Signalling Process
D104
Q100
2SK508NV
TX-VCO
cpu
Pre
Emphasis
SF
AMP(TX)
sp Amp
Tone
AFMOD
Mic amp
U200
AN29160AA
PROCESSER
信令输入
AF
HPF
5th-HPF
mic
MIC
AF
mute
volume
mic mute
LIM
(TX)
0
Figure 7
Tx Audio Process: The audio signal input from the MIC is converted to electrical signal through the
audioelectric conversion of MIC and the amplitude limit is amplified at U200 after the signal is
pre-emphasized. The processed signal goes to the low-pass filter circuit to remove frequencies above
3KHz and then goes to VCO for direct frequency modulation after passing through potentiometer VR200.
Tx Sinalling Process: MCU outputs, via the QTO port, signalling encoder waveform, which is divided into
two parts for modulation after passing through the RC network. One part is used to modulate PLL
reference frequency oscillator directly, while the other part is used to modulate VCO. VR260 balances
the modulation and adjusts the signal amplitude ratio of one part to the other, which optimizes the
singalling waveform modulated on the carrier.

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16
2. Diagram for Rx Audio & Signalling Process
RX
sp Amp
2ndIF BPF
SF
AMP(TX)
VOX
Tone
tone-LPF
DET
BGR
EN
RSSI
Mic amp
VCO
DATA
0
5th-LPF
IFAMP2
AF
HPF
PE
信令输出
5th-HPF
IFAmp1
SW
To MCU
IC
CF300
450KHz+/4.5K
OUT IN
VREF
TX
De
Emphasis
LATCH
AF
mute
SPVCC
volume
To MCU
CDC/CTC
MCU
mix2
mic mute
POWERREG
VCC
LIM
(TX)
SQ
AUDIO OUT
16ΩIW
U201
AF
AMP
U200
AN29160AA
PROCESSER
Figure 8
U200 outputs the initial audio signal (including noise, signalling, audio, etc) after performing
frequency-discrimination and demodulation on the received signal. Therefore, the audio process is
divided into three parts:
Rx Audio Process: One part of the audio signal output by U200 is fed to the RC low-pass filter and
de-emphasis circuit and then amplified at U200. The audio signal is recovered after frequencies below
300Hz are removed at U200. The recovered audio signal is adjusted by the potentiometer and then goes
to audio power amplifier U201, which amplifies power for the input audio signal to drive the speaker
directly. To obtain higher power, the BTL bridge dual-end output is utilized.
Rx Signalling Process: One part of the audio signal output by U200 is fed to the 300Hz low-pass filter
circuit (U640). After audio signals above 300Hz are removed, CTCSS/CDCSS goes to the QTIN pin of
CPU, which decodes the input signals.
Nuisance Signal Process: One part of the audio signal output by U200 goes to U200 again. After the
signal is filtered, amplified and rectified inside U200, a DC voltage signal (SQ) corresponding to the
noise component is derived. The DC signal is fed to the BUSY pin of MCU via the ND pin of U200. Then
MCU processes the input signal.

TC-610/620 Service Manual
17
MCU Control Section
The diagram for the MCU control section is shown below. MCU works on the 7.3728MHz clock
frequency.
Channel SW
MB95F108AK
WPFV-GE1
U605
PTT
MON
BAT
AT24C64
U609
APC/TUNE
PLL
1.vox
2.BUSY_DET
8.UART
7.W/N
6.DC/CTC
5.SAVE
4.T/R
3.BEEP/CALL
X601
9.BAT_DET
U610
Reset
IC
10.PLL_LD
7.3728M 晶体
Figure 9
The MCU control section is composed of MCU, EEPROM, RESET IC, keys, Channel Selector knob, etc.
Main functions realized by this circuit are:
1. Control Signal:
Control of battery save mode
Control of high/low power select
Control of wide/narrow band select
Control of Tx-Rx switch
Control of APC/TUNE output voltage
Control of Tx power supply and power supply of audio power amplifier
Control of squelch ON detect
2. Signal Detect
Detect of external PTT, MONI and VOX enable
Detect of PLL unlock (UL)
Detect of VOX ON level
Detect of battery power alert
Detect of external earpiece enable and check

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3. Data Transmission and Process
EEPROM data initiation
Programming data transmission
Encode process of Channel Selector knob
Signalling encode and decode
Data transmission of baseband processor (PLL)
Power Supply Process
Diagram for the Circuit
SW
Q611
power management
Vin
VSS
Vout
- - -
7.2V
U606
L604
601s
SAVE
FMMT717FMMT717
Q612
5V
UPA572T
Q610
TXC
V-TX POWER-SAVE
Figure 10
After the radio is powered on, the battery voltage is provided to the RF power amplifier and audio power
amplifier, to meet the requirements of sufficient power amplification after filtered by L604 and C682.
Another path is input with the 5V regulator (U606) and outputs VCC_5V voltage for use by MCU and the
baseband processor after regulated. Because the radio works in half duplex mode, it is required to
control the Tx and Rx power supply alternately. To meet the requirement of the battery save mode, MCU
should output a pulse signal with fixed duty factor (control signal of SAVE). When the SAVE signal of
MCU is of high level, Q610 is on and provides a 5V voltage (V_SAVE) for the operating circuit. PLL and
the receive circuit operate. When the SAVE signal is a pulse signal, the radio enters the battery save
mode. When transmitting, TXC, control signal of CPU, is of high level. Q611 is on and provides a 5V
voltage (TX_VCC) for the transmit circuit. The transmit circuit operates.
Power supplies of the Tx section and Rx section both have symmetrical regulation measures. When the
load change changes the output voltage/current, the regulator closed-loop feedback circuit operates,
regulating the output voltage at 5V.

TC-610/620 Service Manual
19
VOX Realization
The diagram is shown below:
Q202
2SA1832
1
2 3
Q201
2SK1824
2
31
J4
MICJACK
2431
VCC_5V
R251
1M
MIC_EN
EXPTT
C260
220P
RXD
mic
X1
-
2
+
1
R201
2.2K
C201
470P
C200
4.7u/10V
R203
4.7K
VCC_5V
R200
470
C213
1U
C212
0.1U
R205
47K
C202
0.1U
L200 1UH
R202 100
TP200
R208
100K
R207
56K
R206 1K
R204 470
C274
0.01U
Figure 11
After the function key VOX is held down, the radio enters the VOX mode. The VOX function can only be
enabled when MCU detects that MIC enable signal (MIC_EN) and external VOX enable signal (EXT-PTT)
switch from low level to high level almost at the same time (within hundreds of milliseconds). Otherwise,
it is detected as the earpiece without VOX and the VOX function is off.
1) When the earpiece with VOX is inserted into the accessoryjack, Q201 is off. MIC_EN switches from
low level to high level and Q202 completes the circuit with R204 and the external earpiece
simultaneously. Q202 is on and EXT-PTT switches from low level to high level, which is detected by
MCU as the insert of an earpiece with VOX. The VOX function is enabled. When the VOX detect
level (5 levels available) meets the preset requirements, the radio transmits and the audio signal
goes to baseband processor AN29160 through the process path.
2) If an earpiece without VOX (earpiece with PTT) is inserted, Q201 is off. MIC_EN switches from low
level to high level, but Q202 can not complete the circuit and keeps the cut-off status. EXT-PTT is of
low level. MCU detects as the earpiece without VOX and the radio returns to normal mode. Press
the PTT key on the earpiece to transmit.