LG B1200 Schematics 5
3. FAILURE LIST
3. FAILURE LIST
FAILURE ITEM L1 L2 L3
NO RING TONE V
RING TONE DISTORTION V
NO KEY TONE V
AUDIO NOISE V V
POOR VOICE QUALITY V V
LOW VOICE VOLUME V V
RECEIVER / EARPIECE MUTE V V
POOR HANDFREE VOICE QUILITY V
TOTALLY DEAD/NO POWER V V
UNEXPECTED POWER ON V
UNEXPECTED POWER OFF / POWER OFF BY PLUG IN A EARPIECE
RANDOM TIME DISPLAY V
CLOCK RESET AT POMER ON / CLOCK DEAD V V
NO SERVE FOUND/NO NET WORK REGISTER V
ROAMING AT POWER ON / UNEXPECTED INTERNATIONAL ROAMING
WRONG IMEI CODE V
LCD NOT DISPLAY V
LCD DISPLAY MISSING ROW/LCD DISPLAY DETECT V
BLACK LCD V
FLICKING LCD DISPLAY / DISPLAY UNSTABLE V
BLACK LINE ON LCD DISPLAY V
RANDOM LCD DISPLAY V
LED FAIL V
WEAK SINGAL/ECHO IN TALKS V
NO TRANSMIT / RECEIVE V
ANTENNA DEFECT V
INCOME CALLS CAN'T BE PICKED UP V
REMOTE SIDE AUDIO MUTE V V
SIGNAL INTERCEPT V
BAD CHARGER CONNECTOR V
CAN'T POWER ON AFTER CHARGING V V
SHORT WAITING HOURS V V
HIGH POWER CONSUMATION V V
BATTERY DAMAGE V
BATTERY CAN'T BE CHARGED V
BATTERY LEVEL DON'T DISPLAY V
BATTERY LEVEL DISPLAY NOT CORRECT V
INCOMPATIBLE WITH BATTERY V
SIM CARD UNRECOGNIZE V V
BAD SIM CARD CONTACT V
UNEXPECTED SIM CARD LOCK V
HOUSING DAMAGE V
BAD KEYPAD RESPONSE V V
V
V
- 30 -
4. TROUBLE SHOOTING
- 31 -
4. TROUBLE SHOOTING
Power Supply Failure
a) Failure :
- Problem with turning on mobile phone
Solution:
- Test the set’s current by using battery
simulator: observe the value of current used
- Case 1:
If the Current is higher than 300mA, please
check C223~C227, if short circuit, Replace it.
- Case 2:
In the case the current is between 10 and 30mA,
The cause could be FLASH ROM(U301) defect,
please use monitor to re-install software. If the
software can’t be re-install through serial port,
use JTAG interface to re-install software.
b) Failure :
- Problem with charging the battery
- Charging connector damage
Solution :
- J104 may be bad connection or broken, check
the connector.
- J104 may be a cold soldering, Please re-solder
again.
- If J104 is broken, replace the connector
carefully
c) Failure :
- The value of the charging current look like short
circuit.
Solution :
- Re-install the software
- Check Q101, if short circuit, replace it.
4. TROUBLE SHOOTING
- 32 -
Software Download Failure
a) Failure :
- Problem with software download
Solution :
- J104 may be bad connection or broken, check
the connector.
- J104 may be a cold soldering, Please re-solder
again.
- Check R104,R105& R109, if cold soldering,
Please re-solder again.
Voice Function Failure
a) Failure :
- Microphone voice failure
Solution :
- Check M301, the microphone holder may be
bad connection
- Test the bias voltage on R301, it should be
2.5V,
- Replace Microphone, if microphone holder &
bias voltage is fine.
b) Failure :
- Speaker failure
Solution :
- check speaker connector, it may be bad
connection.
- Check U302 and related circuit, if short circuit,
replace it.
c) Failure :
- Headset function failure
Solution :
- J104 may be bad connection or broken, check
the connector.
- J104 may be a cold soldering, Please re-solder
again.
- If J104 is broken, replace the connectorcarefully
4. TROUBLE SHOOTING
- 33 -
Display Function Failure
a) Failure :
-No display on LCD
Solution :
-Test the capacitance of C319~C327 by using
multi-meter, the value should be infinity.
Replace the capacitor, which has any
impedance.
- Test the resistance of R311~R313, if cold
soldering, Please re-solder again.
- Otherwise, replace LCD module .
b) Failure :
- Broken LCD
Solution :
- Replace whole LCD module.
- Solder the LCD module with care.
c) Failure :
-Fails on dark display, black line, short of lines,
unstable brightness
Solution :
- Test R311,~R313, if cold soldering, Please re-
solder again.
- Test C319~C327, if cold soldering, Please re-
solder again.
- Otherwise, Replace whole LCD module.
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