C4+ (PGN-403) Service Manual
C4+ (PGN-403) Service Manual
C4+ (PGN-403) Service Manual
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CONTENT
1 OUTLINE..................................................................................................................................................3
2.1 RF PART.............................................................................................................................................6
2.1.1 Block Diagram of the RF Section..............................................................................................6
2.1.2 Signal Flow OF the RF Transmitting Part...................................................................................7
2.1.2.1 Receiving and Transmit Path.............................................................................................7
2.1.2.2 Maintenance Procedures of the Transmitting Part...........................................................8
2.1.3 Signal Flow of the Receiving Part.............................................................................................9
2.1.3.1 Receiving Part Components..............................................................................................9
2.1.3.2 Maintenance Procedures of the Receiving Part..............................................................9
2.2 BASEBAND PART................................................................................................................................11
2.2.1 Block Diagram of the Baseband Part......................................................................................11
2.2.2 Power Management Part.......................................................................................................12
2.2.2.1 The Whole Power Supply System....................................................................................13
2.2.3 Audio Part...............................................................................................................................14
2.2.3.1 Audio CODEC Circuit.......................................................................................................14
2.2.3.2 MIC, RECEIVER LOOP.......................................................................................................14
2.2.3.3 HEADSET LOOP................................................................................................................15
2.2.4 BASEBAND FAUIT ISSUES........................................................................................................16
2.2.4.1 Analysis of the Keyboard Fault........................................................................................17
2.2.4.2 Analysis of the Display Module Circle.............................................................................18
2.2.4.3 FM Module......................................................................................................................19
2.2.4.4 Camera Module...............................................................................................................20
2.2.4.5 IO Interface......................................................................................................................21
2.2.4.6 SIM Card Circuit..............................................................................................................21
2.2.4.7 T-FLASH Card Circuit.......................................................................................................22
2.2.4.8 BT Circuit........................................................................................................................22
2.2.4.9 WIFI Circuit.....................................................................................................................23
2.2.4.10 GPS Circuit....................................................................................................................24
2.2.4.11 M-sensor Circuit...........................................................................................................24
2.2.4.12 G-sensor Circuit............................................................................................................25
2.2.4.13 IR-sensor Circuit...........................................................................................................25
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1 Outline
Band1 23dbm
Band8 23dbm
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DCS -108 dbm
EGSM 28.8dbm
DCS 28.0dbm
TRP
PCS 28.0dbm
Band 1 20.0dbm
Band 8 20.0dbm
EGSM -105dbm
GSM850 -105dbm
DCS -106dbm
TIS
PCS -106dbm
Band 1 -107dbm
Band 8 -107dbm
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CAMERA
SKY77590
FM 、 BT 、 WiFi 、 GPS
MT6166
CPU
MT6582V/X
LCD : 960*540
CTP
HP
KEYPAD REC
MIC
T-FLASH
MEMORY
PMIC
SPK
MT6323GA
BATTRY
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1.2 Motherboard Components Distribution
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2 Signal Flow And Fault Analysis
2.1 RF Part
2.1.1 Block Diagram of the RF Section
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GGG
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RF Diagram
MT6166 MT6582V/X
Receiving
Transmit
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2.1.2.2 Maintenance Procedures of the Transmitting Part
( NO launch ) Connect the PC and the phone with maintenance line, then making the phone into the RF state with META soft
N
Check Transceiver to see if IO signals exist. Check CPU
`
Y Y
CheckVBAT,PA_EN,BANDSW_DCS,VAPC 是否 OK?
N
N
Replace PA
Check RF coaxial
switch or matching
network.
Y
Check CPU
Replace Transceiver
ANT
CPU
MT6582V/X
PA &
Ant Switch
SKY77590 Transceiver
MT6166
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2.1.3 Signal Flow of the Receiving Part
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No receiving
Start the META software to connect the PC and the phone , making the phone into the receiving state.
Signal generator is also adjusted to the correspond CH. And signal lines connected to the phone.
的同轴开关上。
N
Transceiver has received signal?
? N
Y
N
Check to see if there has
signal in the matching circuit
Y between PA and ANT Y
Check
Whether
CPU the voltage of the transceiver is normal? Whether 26MHZ is normal?
正常?
Check to see if there has
signal in the matching
circuit between PA and
transceiver
N
Check the
corresponding power
supply and 26MHZ
Y
resulting circuit
Replace transceiver
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2.2 Baseband Part
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CAMERA
SY77590
FM 、 BT 、 WiFi 、 GPS
MT6166
CPU
MT6582V/X
LCD : 960*540
CTP
HP
KEYPAD REC
MIC
T-FLASH
MEMORY
PMIC
MT6323GA SPK
BATTRY
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2.2.2 Power Management Part
The power management Part use the special PMU IC : MT6323. Support 5-ways of DC-DC
and 21-ways of LDO output, with AB/D, 0.7W Audio amplifier, LCD backlight driving and
Lithium battery charging circuit Inside it. Which support 5 LEDs in parallel and 10 LEDs in
series.
DC-DC:
LDO
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2.2.3 Audio Part
MIC Audio channel is shown below: This product uses the single analog MIC in order to reduce
noise when you use voice calling. The power supply voltage is 1.8V-2.1V. When MIC is in good
condition but loop MIC has no echo, then you need to check the basic bias voltage signal of the
MICBIAS, the language signals of the RECEIVER and MIC also need to be checked.
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Receiver:
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2.2.3.3 HEADSET LOOP
Headset loop includes two signals: Headset speaker and MIC, the jack is SMT in the main-board.
If the Headset speaker has no sound、the MIC is invalid. All this need to check the SMT of the
J402
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Download Fail
NO
Check the power manager and open the LDO to see if the voltage supply is normal VCORE 、
and whether
Check VDDis、
there power
VADD 、 VTCXO
supply circuit、 VRTC 、
open.
The keypad is in a FPC, connect with mainboard by J1501.This board includes 3 side-buttons. All
the keyboard circuits use the scanning method to detect except the power button, volume up
and down. The scanning signal will be triggered when a button is pressed,, then the
corresponding row and column will be detected, the function of the key can be identified
according to the software definition.
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a. The cell phone can power on ,but all the keys are invalid.
In general, this situation is caused by some key short-circuit, the equivalent of a long
pressing this button.
At this point ,you should analyze the following first:
⑴ Check peripheral TVS of the button to see if they are short-circuit.
⑵ Then ,check the connector to see whether it is short-circuit when it is welded.
b. Failure of a single button
This situation needs to check whether the beneath of the DOME key is dirty. If the
problem is still existed, you have to check whether the circuit is open.
c. Failure of a few buttons
This situation is usually caused by a short-circuit row or column. Checking the interface
circuit to see if it has open weld phenomena and detect the disconnected
phenomena of the resistance.
Display module use the 4.7" LCD, which including 2 pairs MIPI differential bus mode. All of
commend and data go through the MIPI differential bus mode except the reset signal.
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For the screen problem you should first use the alternative method to search out whether the
problem is in the motherboard or the LCD. Focus on examining the LCM connector and EMI filter
welding.. The backlight signal is completed by the LED driver chip SGM3736. Generally, measure
the input voltage VBAT and the enable control signal.
2.2.4.3 FM Module
The WIFI Circle is based on chip MT6627, comes with FM module and transmitter function, also
with both analog and digital audio channels choose from. The RF part supply short antenna
design and long antenna design.
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FM use the headphone ground as the antenna , therefore the headset ground and the
motherboard ground have2500@100M magnetic beads to isolate FM(80M~108M)signals.
The module uses 8 million pixel AF camera as the main camera, 2.0 million pixel camera as the
sub camera. Through the connector and the baseband chip (the main camera series EMI devices)
directly connected.
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The Camera Power Supply Circuit
The VCAM_IO_PMU supply 1.8V to Camera IO interface voltage, VCAMA_AVDD supply 2.8V
analog voltage.
2.2.4.5 IO Interface
Switch of dual SIM cards is integrated into baseband, which supports dual SIM Card function,
SIM1 support GSM/WCDMA Card, SIM2 support only GSM Card.. As show below:
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2.2.4.7 T-FLASH Card Circuit
The T-FLASH Card Circle support data exchange between Phone and PC. The Circuit have four
serial data transmission lines ( MCODA0,MCODA1,MCODA2,MCODA3 ) and state
detection(MCOCMD),CLOCK(MCOCK),as the show below:
2.2.4.8 BT Circuit
The Bluetooth function is one part of the MT6627 .The BT Circuit include baseband, RF unit,
UART2 unit, PCM interface system configuration, and also.
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2.2.4.9 WIFI Circuit
The WIFI Circuit integrated in MTK6627, The WIFI Circuit includes baseband, RF unit, power,
SDIO interface system configuration. It supports 2.4G, following 802.11b/n/g agreement,
supports safety format is WFA, WPA/WPA2, WPS2.0, WAPI.
The WIFI’S RF interface is connected with external antenna. The ANT is transmitting or receiving
signals to communicate with WIFI equipment.
The GPS Circuit integrated in MTK6627, It includes baseband, RF unit, power, UART interface
system configuration. Its sensitivity supports 165dBm, supports AGPS.
The GPS’S RF interface is connected with external antenna. The ANT is receiving GPS satellite
signal to achieve positioning. GPS and BT share the same ANT. We switch GPS signal by the
switch U904, then through a narrowband filter U903 into GPS chip.
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2.2.4.11 M-sensor Circuit
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2.2.4.13 IR-sensor Circuit
IR-SENSOR is light &distance sensor. It induces current phone the environment in which of the
brightness and Perceived distance of the human face in the phone calling and the phone. IR-
SENSOR uses I2C to connect CPU interface, in order to transmit directives and data, also we
need an INT give CPU a trigger signal.
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3. Disassembly and assembly service Tools
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