FLY DS185, 190B Service Manual
DS185（X190B） Service Manual
Version number: V1.0
Draft Liu Changling
Auditing Tang Yin
Authorize
Date 2010-2-4
Longcheer Technology (Shanghai) Co., Ltd.
Contents
1 Overview DS185 ......................................................................................................................1
1.1 About DS185 Phone......................................................................................................1
1.2 Distribution of the mainboard components...................................................................2
2 Signal flow and fault analysis.................................................................................................5
2.1 RF..................................................................................................................................5
2.1.1 RF diagrams......................................................................................................5
2.1.2 RF transmit signal flow.....................................................................................6
2.1.3 RF receive signal flow ....................................................................................12
2.2 Baseband.....................................................................................................................19
2.2.1 Baseband diagrams..........................................................................................19
2.2.2 Power management.........................................................................................20
2.2.3 Minimum System part.....................................................................................22
2.2.4 Audio Frequency.............................................................................................24
2.2.5 Bluetooth.........................................................................................................27
2.2.6 Baseband common malfunction......................................................................28
DS185 Service manual
1 Overview DS185
1.1 About DS185 Phone
DS185 mainboard is designed based on the MTK platform, supporting two-frequency
communications. The mainboard also supports multimedia functions, such as MP4, MP3,
0.3m/pixels camera, USB and FM radio. The mainboard system consists of the base-band
（MT6225, the RF part (MT6139) and the Power management unit (MT6305).
DS185 system diagram
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DS185 Service manual
1.2 Distribution of the mainboard components
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DS185 Service manual
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DS185 Service manual
Name Model Location
MTK BB MT6225A/BGC-L D200
MTK PMU MT6305BN/CY-D-L // MT6305BN(CY-D-L) U501
Touch Screen Controller TSC2046IRGVR U602
NOR+PSRAM(128Mb+32Mb,1.8V) K5L2833ATA-AF66 D601
Bluetooth BC313141A18-IXF-E4 U902
Bluetooth filters DBF81F116-CSR-T U901
Dual SIM Card Controller MT6302N D401
Backlight Driver IC (4-way common
cathode)
RF Amplifier AX502 U102
RF front-end switch (tri-band) LMSP33CA-465 U103
FM AR1010-S85QFG*0 U801
LDO(2.8V, 300mA) RT9193-28PU5//RP1202-28PU5 U108,U812
LDO(3.3V, 300mA) EUP7967A-33VIR1 U401
LDO(1.8V, 2.8V, dual 150mA) PAM3102-AST26R1 D700
Stereo audio amplifier A7013M D704
Orientation sensor RPI-1031 U603
AAT3104IJQ-2-T1 U502
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DS185 Service manual
2 Signal flow and fault analysis
2.1 RF
2.1.1 RF diagrams
X190 mainboard adopts the plan of MTK MT6139.
RF part mainly consists of transceiver MT6139 (adopts program of near-zero IF receiver,
supporting the GSM / EGSM / DCS / PCS and 26M VCTCXO as the clock input,
integrated clock buffer, LO VCO and TX VCO and regulator, only need for external
connections of VBAT / AVDD). It uses Dual-band transmitter module AX502 (it supports
GSM / DCS / and integrated power control).
Function:
1. PA（AX502）supports EGSM / DCS / PCS and integrated FEM and automatic power
control which adopts voltage control to achieve and its role is to amplify the signal power
in accordance with the requirements. It is divided to two different power levels through
VRAMP signal. The transmit signal of GSM is 5 to 19, power is from 3.2MW to 2W while
DCS is 0 ~ 15, power from 1MW ~ 1W. PA is time-sharing work controlled by TX-EN chip,
the output power of PA is controlled by VRAMP (APC) through the voltage. PA is
intermittent work, by the BS to achieve the choice of frequency bands. Front-end module
FEM is the selection switch to select RX/TX and GSM/DC BAND, to increase the isolation
and prevent crosstalk between signals.
2. Transceiver (MT6139) has the RF modulation and demodulation, frequency synthesis
and clock buffering functions, that is to convert high-frequency to low-frequency and
low-frequency converted into high-frequency.
a. Transmit: MIC - MT6225 - MT6139 – PA - ANT
b. Receive: Antenna RX – FEM - SAW filter - MT6139 - CPU
A
N
T
PA
Ax502
Transceiver
MT6139
RF diagram
CPU
MT6225
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DS185 Service manual
MT6139 MT6225
GSM RF and BB interface diagram
2.1.2 RF transmit signal flow
z Transmit Circuit
TX is composed of the modulation loop, power amplifier and antenna switch. PLL is
mainly in the internal MT6139, I / Q signal first enters into the MT6139, after entering the
TXVCO, the signal is modulated to RF, and then it outputs from the chip to PA（AX502）,
converts into electromagnetic energy through antenna by the antenna switch after
enlarged. Build PI-type attenuation resistor networks from the MT6139 to PA. Antenna
switch to select RX, TX , as well as GSM, DCS.
z Maintenance Flow
z Maintenance preparation
Test conditions 1：Vbatt=3.8v~4.2v
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DS185 Service manual
p
k
Test conditions 2: GSM Band
Tx Mode CH62 Freq=902 4MHz Power Level：5
Test conditions 3: DCS Band
Tx Mode CH700 Freq=1747 8MHz Power Level:0
Test Equipment: CMU60100, Oscilloscope, Spectrum analyzer
z Detection and Maintenance Flow Chart
(No transmit) Connect PC and cell
phone with maintenance of line, use
the Repair software making mobile
hone access to transmit state.
Y
Chec
whether there is IQ
signal?
Transceiver,
Y
Check PA output,
whether there is any RF
signal?
VBAT, PA_EN,
BANDSW_DCS, VAPC,
are they OK?
Y
N
N
N
Check CPU
N
Check Transceiver,
whether there is any RF
output signal?
Y
N
Check Transceiver
LE 、 SCLK/SDATA 、
RFVCOEN 、 VCXOEN,
are there correct signal?
Replace PA
Check RF switch or
matching network
Check CPU
Replace Transceiver
Y
z The maintenance process of Transmit malfunction
Use the Repair software making mobile phone access to transmit state. Choose 62CH in
GSM band, POWER Level for 5, DCS for 700CH, POWER Level for 0. Then, first observe
whether the current rises, and use the spectrum analyzer and oscilloscope to observe the
signal given in the above-mentioned flow chart, the specific signal waveforms shown as
below:
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DS185 Service manual
IQ signal waveforms of transceiver in transmit state:
3.10 I/Q
RF interface spectrum analyzer is as follows:
GSM transmit signal
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DS185 Service manual
DCS transmit signal
PA-EN waveforms of PA in transmit state:
PA-EN
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