FLY iq4490i Service Manual
FLY SERVICE SUPPORT
IQ4490i Service Manual V1.0
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Contents
1. IQ4490I overview ................................................................................................................. 3
1.1 IQ4490I brief introduction .................................................................................................. 3
1.2 Function diagram ................................................................................................................ 4
1.3 Mainboard component distribution diagram ....................................................................... 5
1.4 Main IC Names ................................................................................................................... 7
2. RF ......................................................................................................................................... 8
2.1 WCDMA RF power trouble ................................................................................................ 8
2.2 GSM RF power trouble .......................................... Ошибка! Закладка не определена.
2.3 WCDMA RX trouble ........................................................................................................ 11
2.4 GSM RX trouble ............................................................................................................... 12
2.5 WiFi/BT Part .................................................................................................................... 14
3. Baseband section ................................................................................................................ 15
3.1 Outline .............................................................................................................................. 15
3.2 Common Failure Analysis and Maintenance .................................................................... 17
3.2.1 Power failure Check .............................................................................................. 17
3.2.2 Audio faults ........................................................................................................... 18
3.2.4 LCD Fault .............................................................................................................. 21
3.2.5 FM ......................................................................................................................... 22
3.2.6 Camera fault ................................................................................................................... 22
3.2.7 SIM card failure .................................................................................................... 23
3.2.8 Motor test is invalid ............................................................................................... 24
3.2.9 Gravity Sensor ....................................................................................................... 24
3.2.10 T-Flash fault ......................................................................................................... 25
3.2.11Touch Panel function ............................................................................................ 26
3.2.13 Cannot boot failure .............................................................................................. 26
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1. IQ4490I overview
1.1 IQ4490I brief introduction
The development and design of the IQ4490I PCBA is based on SC7715A platform. The mainboard system mainly
consists of the chip SC7715A+SR2351 +SR3131, which are responsible for three part functions, namely, baseband,
radio frequency and power management chip. IQ4490I PCBA is an all-in-one phone mainboard, which supports GSM,
WCDMA, and covers Bluetooth, WIFI, Camera, FM functions, and so forth.
The maintenance of mainboard is one of the important links among mobile products rear-end producing. The
speed and quality of maintenance relate to the rate of good products, production efficiency, and cost control
throughout the producing. In the case of a reasonable design of product, in the end-producing, finding the significant
proportion in the bad board should be SMT bad and component incoming material bad. So, when maintaining, first,
start with the two aspects. The principal means of fault diagnosis are: (1) find that bad welding spots or components
by microscopic examination and visual inspection; (2) guess failure positions from the fault phenomena; (3) confirm
the fault units by signal detection.
1.2 Function diagram
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1.3 Mainboard component distribution diagram
Mainboard TOP
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Mainboard BOTTOM
1.4 Main IC Names
Ite
m
Description
PN
REF
1
SC7715A;570;FCVFBGA;13.3X12.1;040;BB;WCDMA
SC7715A
U201
2
IC,MEM,FBGA162,4GB/4Gb,6/1.9nS,e-
MMC/LPDDR2,4Gbx8/128Mx32,1.8V/3.3V,MCP,1.8/1
.2V,MCP
KMN5X000ZM-B209
U401
3
Chip Scale Packaged Fully Integrated Thermal
Accelerometer-2D-8bit-3*3mm-IO1.8V
MXC6255XC
U501
4
Electric Double Layer Capacitor-3.3V-0.033F-
13.8uAH-纽扣型-Φ3.8mm-高1.5mm
SM3R3333T01
U502
5
SR2351;38;QFN;5.5x4.5;040;RF
SR2351
U801
6
LDO; 3.3V; 300mA; 300mV; SOT23-5L
WL2801E33-5/TR
U802
7
Switch+PA;3.3V;2.4-2.5GHz,Small 16L QFN
2.5x2.5x0.45m㎥
RTC7626
U803
8
SAW;2450MHz;2.1;2.0;2x1.25x0.9
LFB212G45CL1D172
U808
9
SR3131;50;QFN; 5.5x7; 040; RF; 3G
transceiver
SR3131
U901
10
PA QuadBand GSM/GPRS and Dual-Band WCDMA
Handsets
• LGA 6mm x6mm x0.9mm
SC2662H
U902
11
PA Module for
WCDMA/HSDPA/HSUPA/HSPA+Application
• 3mm*3mm*0.9mm
SC2671H
U903
12
SAW DUPLEXER FOR UMTS BC1
SAYRF1G95HQ0F0A
U904
13
PA Module for
WCDMA/HSDPA/HSUPA/HSPA+Application
• 3mm*3mm*0.9mm
SC2678H
U905
14
SAW DUPLEXER FOR UMTS BC8
SAYFH897MHC0F0A
U906
15
晶体-32.768KHz-12.5PF-+/-20PPM-65kΩ-
7.0mm*1.5mm*1.4mm
Q13MC1462000200
X501
16
26M 8pF 10ppm Crystal NX3225SA
7V26000015
X901
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17
SAW FILTER FOR GSM1800/GSM1900 (Rx)
SAWEN1G84CV0F00
Z907
18
Gate;single;buffer with 3-state
output;0.8V~3.6V;sc70
SN74AUC1G125DCKR
U804
19
SAW滤波器-1575.42/1602MHZ-0.9DB-1.4*1.1*0.6
SAFEA1G58KA0F00
U805
U806
20
SiGe:C Low Noise Amplifier MMIC for GPS,
GLONASS and Galileo
BGU7005
U807
2.1 WCDMA RF power trouble
Check points
-PA connector soldering
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-Duplexer connector soldering
-Other Tx RF Component soldering
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Start
Replace PA
Check PA
connector
soldering is ok?
Yes
Check Dupolexer
connector is ok?
No
Resoldering
No
Resoldering
Yes
Check Other Tx RF
components
soldering is ok?
No
Resoldering
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