Text preview for : Failure list_Trouble shooting.pdf part of LG LG 1200B Service manual for LG 1200B



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3. FAILURE LIST

3. FAILURE LIST
FAILURE ITEM NO RING TONE RING TONE DISTORTION NO KEY TONE AUDIO NOISE POOR VOICE QUALITY LOW VOICE VOLUME RECEIVER / EARPIECE MUTE POOR HANDFREE VOICE QUILITY TOTALLY DEAD/NO POWER UNEXPECTED POWER ON UNEXPECTED POWER OFF / POWER OFF BY PLUG IN A EARPIECE RANDOM TIME DISPLAY CLOCK RESET AT POMER ON / CLOCK DEAD NO SERVE FOUND/NO NET WORK REGISTER ROAMING AT POWER ON / UNEXPECTED INTERNATIONAL ROAMING WRONG IMEI CODE LCD NOT DISPLAY LCD DISPLAY MISSING ROW/LCD DISPLAY DETECT BLACK LCD FLICKING LCD DISPLAY / DISPLAY UNSTABLE BLACK LINE ON LCD DISPLAY RANDOM LCD DISPLAY LED FAIL WEAK SINGAL/ECHO IN TALKS NO TRANSMIT / RECEIVE ANTENNA DEFECT INCOME CALLS CAN'T BE PICKED UP REMOTE SIDE AUDIO MUTE SIGNAL INTERCEPT BAD CHARGER CONNECTOR CAN'T POWER ON AFTER CHARGING SHORT WAITING HOURS HIGH POWER CONSUMATION BATTERY DAMAGE BATTERY CAN'T BE CHARGED BATTERY LEVEL DON'T DISPLAY BATTERY LEVEL DISPLAY NOT CORRECT INCOMPATIBLE WITH BATTERY SIM CARD UNRECOGNIZE BAD SIM CARD CONTACT UNEXPECTED SIM CARD LOCK HOUSING DAMAGE BAD KEYPAD RESPONSE L1 L2 V V V V V V V V V L3

V V V V

V V V V V

V V V V V V V V V V V

V V V V V V V V V V V V V V V V V V V V V V V V V V

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4. TROUBLE SHOOTING

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.

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4. TROUBLE SHOOTING

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

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4. TROUBLE SHOOTING

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 resolder again. - Test C319~C327, if cold soldering, Please resolder again. - Otherwise, Replace whole LCD module.

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4. TROUBLE SHOOTING

d) Failure : - No Back-light Solution : - Replace the LED that doesn't light up including any failing parts of LED. - If all of the LED fails, Please check Q301, Q302 and related circuits.

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