LG Phones G Series G4

LG-H815
The LG-H815 is the international model of the LG G4.

Checking XO Block
Output frequency = (19.2MHz). X4100 is used as the reference. one of WTR3905 and PM8994 internal VCO.
 * Check TP1 - Is it 19.2MHz?
 * Yes - move to next flow
 * Replace X4100 and then check TP1
 * Yes - move to next flow
 * Logic Troubleshooting

Transceiver DC Power Supply Circuit

 * Check TP1 +1V_RF is OK?
 * No - Logic Troubleshooting
 * Check TP2 +1.8V_RF is OK?
 * No - Logic Troubleshooting
 * Next flow

DC-DC Block

 * Check TP1(+VPA0) 0.5V < TP4 < 4.2V ?
 * No - Check U1400 (Physical Damage / soldering condition)
 * Next flow

ASM/FEMiD Block

 * Check TP1, TP2 High Level? (2.5V<TP1 <3.1V) and (1.7V<TP2 <1.9V)
 * No - Logic Troubleshooting
 * Check U1201 (Physical Damage / soldering condition)
 * Bad - Replace U1201
 * Next flow

GSM850/900/1800/1900 Rx

 * Check TP1/2/3/4 Signal exist?
 * No - Check Component above RF signal path
 * Check Transceiver (Physical Damage / soldering condition)
 * Bad - Replace U1500
 * Next flow

GSM850/900/1800/1900 Tx

 * Check TP1 +VPWR OK?
 * No - Logic Troubleshooting
 * Check TP2 3.2V<TP2<4.2V?
 * No - Check DC-DC Block again
 * Check TP3/4 - If GSM850/900 over 31dBm? If DCS/PCS over 28dBm?
 * Yes - Check component above RF signal path
 * Check TP5/6 - If GSM850/900 over 9dBm? If DCS/PCS over 7dBm?
 * No - Check U1301 (Physical Damage / soldering condition)
 * Check Transceiver (Physical Damage / soldering condition)
 * Bad - Replace U1500
 * Next flow

WCDMA (Rx signal path(B1/B2/B5/B8))

 * Check TP1/2/3/4 Signal exist?
 * Check U1201
 * Check Transceiver (Physical Damage / soldering condition)
 * Bad - Replace U1500
 * Next flow

WCDMA (DRX RF signal path (B1/2/5/8))

 * Check TP1/3/5/7 Signal exist?
 * No - Check SW1106 (Physical Damage / soldering condition)
 * Check TP2 exist
 * No - Check B1 FL1100 (Physical Damage / soldering condition)
 * Check TP4 Signal exists?
 * No - Check B2 FL1124 (Physical Damage / soldering condition)
 * Check TP6 Signal exists?
 * No - Check B5 FL1131 (Physical Damage / soldering condition)
 * Check TP8 Signal exists?
 * No - Check B8 FL1116 (Physical Damage / soldering condition)
 * Check Transceiver (Physical Damage / soldering condition)
 * Bad - Replace U1500
 * Next flow

Power
The output frequency(19.2MHz) of XO(X4100) is used as the reference one of PM8994 internal VCO
 * Voltage 3.4V to 4.4V
 * No - Check BATTERY CN9100 (Battery connector) contact, Replace
 * POWER KEY ON R1 1006 is LOW?
 * No - POWER_KEY Check
 * PM8994 is VREG level check?
 * No - U4100(PM8994 Check)
 * CLOCK CHECK (X4100)
 * No - X4100 PIN CHECK(19.2Mhz)
 * Check TON_RESET_N (TP4204) 1.8V?
 * No - U4100 (PM8994 Check)
 * MSM_PS_HOLD (TP4105) High?
 * No - U2100 (MSM8992 Check)
 * TP1 Check?
 * No - U3200 (eMMC Check)
 * Bad board

USB

 * Check the Connection of USB
 * Connection OK?
 * No - Change I/O connector (CN9201)
 * USB +/- signal OK?
 * No - Change Filter (FL7600)
 * Bad board

Hall effect Sensor (Quick Cover)

 * Magnet Component is normal?
 * No - Check Quick Cover Magnet component
 * HALL IC U8700 voltage High? C8700, TP1
 * No - Check PM8994 voltage +1V8 VREG S4A
 * when working HALL_INT is LOW? C8701, TP2
 * No - Replace HALL IC (U8700)
 * END

Accelerometer / Gyro / Compass / Pressure Sensors

 * Check the sensor function
 * Function is OK?
 * Yes - END
 * Calibration OK?
 * Yes - END
 * Change the sensor IC
 * Function is OK?
 * Yes - END
 * Bad board

Proximity Sensor

 * Send Key click & phone number click & Call connected
 * Object moved at the Proximity sensor
 * LCD OFF?
 * Yes - END
 * Check +3V0_VREG_L18, (C8401). Output work well?
 * Yes - END
 * Bad board

Display
Check CN1 and TP Voltage.
 * Power On SW
 * Power is ON?
 * No - Goto power troubleshooting
 * Main FPCB Connector(CNI) Connected?
 * Yes - END
 * LCD Display OK?
 * No - Check Voltages: TP1: -5.5V, TP2: 5.5V, TP3: 1.8V
 * No - Bad board
 * Replace LCD module
 * LCD Display OK?
 * No - Bad board
 * END

Main Camera
Check CN7300 and TP Voltage
 * Camera Connector (CN7300) Connected?
 * Camera is OK?
 * Yes - END
 * Voltage check: TP: 2.8V, TP2: 2.8V, TP3: 2.8V, TP4: 2.8V, TP5: 1.8V, TP6: 1.05V
 * No - Bad board
 * Check MCLK: TP7: 24MHz
 * No - Bad board
 * Replace Camera Module
 * Camera is OK?
 * No - Bad board
 * END

Front Camera
Check CN7300 and TP Voltage
 * Main Cam Connector (CN7300) Connected?
 * Camera (CN7400) Connected?
 * Camera is OK?
 * Yes- END
 * Voltage check: TP: 2.8v, TP2: 1.8V, TP3: 1.2V
 * No - Bad board
 * Check MCLK: TP4: 24MHz
 * No - Bad board
 * Replace Camera Module
 * Camera is OK?
 * No - Bad board
 * END

Motor
Check Motor Contact
 * Motor Contact is normal?
 * No - Check Motor Contact (VB8800)
 * Motor Driver IC power VPWR(TP1)?
 * No - F MAIN (L8800 : VPWR)
 * Bad board

Speaker (Rear speaker)
Speaker control signals are generate by MSM8992-B(U2100), WCD9330(U6100) Speak Boost_Amp (U6200)
 * Check the Speaker sound and check Speaker contact.
 * Hear the sound from the Speaker?
 * Yes - END
 * Change Speaker Module - hear sound?
 * Yes - END
 * Check Main PCB part (FB6930 FB6931 L6700, L6701) (CN6200, CN6201) Speaker signal OK?
 * Yes - END
 * Bad board

Receiver (Call speaker)
Receiver control signals are generate by MSM8992(U2100), WCD9330(U6100) Voice Receiving path: MSM8992 -> WCD9330 -> Receiver
 * Check the Receiver sound check receiver contact.
 * Hear sound?
 * Yes - END
 * Receiver contact OK? (CN6202 and 7CN623)
 * No - Make it contact PCB, return to "Hear sound?"
 * Change Receiver. Hear sound?
 * Yes - END
 * Check Main PCB inductor (L6800 / L6801 ) Sound OK?
 * Yes - END
 * Bad board

Main Mic

 * Check the MIC signal by test mode or Voice recording
 * Check MIC hole and mesh and MIC- Rubber Voice Signal OK?
 * Yes - END
 * Check parts about MIC Bias VA6923 works well ?
 * Yes - END
 * Check parts about MIC Output (FB6920) works well ?
 * Yes - END
 * Bad board

Sub Mic
Sub mic on bottom of PCB. Handset call noise suppression, Speakerphone noise suppression, camcorder recording (zooming)
 * Check the MIC signal by test mode or Voice recording
 * Check MIC hole and mesh and MIC- Rubber Voice Signal OK?
 * Yes - END
 * Check parts about MIC Bias VA6928 works well ?
 * Yes - END
 * Check parts about MIC Output (FB6921) works well ?
 * Yes - END
 * Bad board

Ear Mic
controlled by MSM8992(U2100) and WCD9330(U6100)
 * Didn't display headset icon and did _ play sound via speaker although headset insert
 * Yes - END
 * Check the left signal and detection line short when headset inserted?
 * Yes - END
 * Change jack (damaged jack)
 * Yes - END
 * Check PCB. Jack Line L6653 headset?
 * Yes - END
 * Bad board

FM Radio

 * Check if the FB5110(TP1) signal exists
 * No - Check the components around Ear-jack (FM ant)
 * Check BCM4339 (Physical Damage / soldering condition)
 * No - Check the components around antenna
 * Bad board