LG LG-L25 User manual

Internal Use Only
Service Manual
LG-L25
Date: Dec, 2014 / Issue 0.9

- 2 - Copyright © 2014 LG Electronics. Inc. All right reserved.
Only for training and service purposes
LGE Internal Use Only
Table Of Contents
1. INTRODUCTION..................................................................... 3
1.1 Purpose ........................................................................................................3
1.2 Regulatory Information.........................................................................3
2. PERFORMANCE...................................................................... 5
2.1 Product Name............................................................................................5
2.2 Supporting Standard..............................................................................5
2.3 Functions of Major Semi-Conductors..............................................5
2.4 HW Features ...............................................................................................6
2.5 SW Features ................................................................................................7
2.6 H/W SPEC.................................................................................................. 10
3. TROUBLE SHOOTING .......................................................... 11
3.1 RF Components ..................................................................................... 11
3.2 LTE & WCDMA & CDMA & GSM Tx SIGNAL PATH ...................... 14
3.3 LTE & WCDMA & CDMA & GSM Rx SIGNAL PATH...................... 15
3.4 Checking RF Tx Level............................................................................ 17
3.5 Checking RF Tx Level (Cont.)............................................................. 25
3.6 Checking RF PRx Level ........................................................................ 28
3.7 Checking RF DRx Level........................................................................ 31
3.8 GPS/WIFI/BT Module............................................................................ 34
3.9 GPS/WIFI/BT SIGNAL PATH ................................................................ 36
3.10 Checking GPS/WIFI/BT...................................................................... 37
3.11 Checking NFC....................................................................................... 43
3. 12 SIM........................................................................................................... 46
3. 13 Side Key ................................................................................................. 48
3. 14 USB .......................................................................................................... 50
3. 15 Gyro Sensor / Accelerometer sensor ......................................... 53
3. 16 Compass Sensor................................................................................. 56
3. 17 Proximity/Ambient Light Sensor................................................. 59
3. 18 Camera................................................................................................... 62
3. 19 LCD .......................................................................................................... 68
3. 20 Touch Trouble Shooting.................................................................. 71
3. 21 Vibrator Troubleshooting ............................................................... 74
3. 22 Audio ...................................................................................................... 76
4. DOWNLOAD......................................................................... 86
5. BLOCK DIAGRAM..............................................................102
6. CIRCUIT DIAGRAM ............................................................111
7. BGA PIN MAP.....................................................................127
8. PCB LAYOUT.......................................................................142
9. CALIBRATION.....................................................................148
10. HIDDEN MENU.................................................................167
11. DISASSEMBLE GUIDE......................................................172
12. EXPLODED VIEW & REPLACEMENT PART LIST .............178

- 3 - Copyright © 2014 LG Electronics. Inc. All right reserved.
Only for training and service purposes
LGE Internal Use Only
1. INTRODUCTION
1. INTRODUCTION
LGE Internal Use Only
1.1 Purpose
This manual provides the information necessary to repair, calibration, description and download the features of
this model.
1.2 Regulatory Information
A. Security
Toll fraud, the unauthorized use of telecommunications system by an unauthorized part (for example, persons
other than your company’s employees, agents, subcontractors, or person working on your company’s behalf)
can result in substantial additional charges for your telecommunications services.
System users are responsible for the security of own system. There are may be risks of toll fraud associated with
your telecommunications system. System users are responsible for programming and configuring the
equipment to prevent unauthorized use. The manufacturer does not warrant that this product is immune from
the above case but will prevent unauthorized use of common carrier telecommunication service of facilities
accessed through or connected to it. The manufacturer will not be responsible for any charges that result from
such unauthorized use.
B. Incidence of Harm
If a telephone company determines that the equipment provided to customer is faulty and possibly causing
harm or interruption in service to the telephone network, it should disconnect telephone service until repair can
be done. A telephone company may temporarily disconnect service as long as repair is not done.
C. Changes in Service
A local telephone company may make changes in its communications facilities or procedure. If these changes
could reasonably be expected to affect the use of the phones or compatibility with the net work, the telephone
company is required to give advanced written notice to the user, allowing the user to take appropriate steps to
maintain telephone service.
D. Maintenance Limitations
Maintenance limitations on the phones must be performed only by the manufacturer or its authorized agent.
The user may not make any changes and/or repairs expect as specifically noted in this manual. Therefore, note
that unauthorized alternations or repair may affect the regulatory status of the system and may void any
remaining warranty.

- 4 - Copyright © 2014 LG Electronics. Inc. All right reserved.
Only for training and service purposes
LGE Internal Use Only
1. INTRODUCTION
LGE Internal Use Only
E. Notice of Radiated Emissions
This model complies with rules regarding radiation and radio frequency emission as defined by local regulatory
agencies. In accordance with these agencies, you may be required to provide information such as the following
to the end user.
F. Pictures
The pictures in this manual are for illustrative purposes only; your actual hardware may look slightly different.
G. Interference and Attenuation
A phone may interfere with sensitive laboratory equipment, medical equipment, etc. Interference from
unsuppressed engines or electric motors may cause problems.
H. Electrostatic Sensitive Devices
ATTENTION
Boards, which contain Electrostatic Sensitive Device (ESD), are indicated by the sign.
Following information is ESD handling:
• Service personnel should ground themselves by using a wrist strap when exchange system boards. • When
repairs are made to a system board, they should spread the floor with anti-static mat which is also grounded.
• Use a suitable, grounded soldering iron. • Keep sensitive parts in these protective packages until these are used.
• When returning system boards or parts like EEPROM to the factory, use the protective package as described.

2. PERFORMANCE
- 5 - Copyright © 2014 LG Electronics. Inc. All right reserved.
Only for training and service purposes
LGE Internal Use Only
2. PERFORMANCE
2.1 Product Name
LGL25 : US Cellula,IMT-2000(EVDO Rev_0&A) /LTE B1,B3,B11,B26 / WCDMA B1,B5 / GPS
2.2 Supporting Standard
2.3 Functions of Major Semi-Conductors
LGL25 Product SPEC
5
Classification Function
MSM8926 Digital Baseband Processor
WTR1625L 4G MODEM
PMIC PM8926 PMIC
K4E2E304EE-AGCE Mobile SDRAM(LPDDR3)
WCN3660A BT/WLAN Tranceiver
LGL25 Product SPEC
4
Item Feature Comment
Supporting Standard
US Cellular,IMT-2000 /GPS
LTE B1, B3, B11, B26
WCDMA B1,B5
Frequency Range
US Cellular TX : 816 ~ 848.19 MHz
US Cellular RX : 861~893.19 MHz
IMT-2000 TX : 1920~1979.95 MHz
IMT-2000 RX : 2110~2169.95 MHz
LTEB1 TX : 1920~1979.9 MHz
LTE B1 RX : 2110~2169.9 MHz
LTE B3 TX : 1710~1784.9 MHz
LTE B3 RX : 1805~1879.9 MHz
LTE B11 TX : 1427.9~1447.8 MHz
LTE B11 RX : 1475.9~1495.8 MHz
LTE B26 TX : 814~849 MHz
LTE B26 RX : 859~894 MHz
WCDMA B1 TX : 1920~1979.9MHz
WCDMA B1 RX : 2110~2169.9MHz
WCDMA B5 TX : 826.5~846.6MHz
WCDMA B5 RX : 871.5~891.6MHz
GPS : 1575.42 MHz