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COMMON TROUBLE SHOOTING TECHNIQUE AND STRATEGIES
Here are some techniques in troubleshooting a Cellphone.
NOT CHARGING
· Check charger if it has 5V-9V
· Check battery pack
· Check battery terminal
· Check charging pin
· Check fuse
· Check inductor coil & charging protector diode
· Check charging IC
· Check power IC/UEM
INSERT SIM
• Check SIM card
• Check SIM terminal/connector
• Check transistor, resistor, capacitor (DTC3)
• Check SIM protector IC (DCT4)
• Check power IC/UEM
NO DISPLAY
• Check rubber or metal connector
• Check LCD
• Check transistor, resistor, capacitor (DTC3)
• Check LCD protector IC (DCT4)
• Check flash / RAM IC
• Check CPU
KEPAD MALFUNCTION
• Check keypad tips
• Check for dirt
• Check for open pattern in each row/column
• Check keypad protector diode
• Check CPU
NO EARPIECE/SPEAKER
• Check cell phone volume
• Check speaker (connected to speaker board interface)
• Lift the speaker connector
• Clean if necessary
• Check each resistor, capacitor, inductor
• Check audio IC/UEM
MICROPHONE
• Check cell phone volume of the microphone
• Check microphone (connected to mic board interface)
• Lift the mic connector
• Clean if necessary
• Check each resistor, capacitor & inductor
• Check audio IC / UEM
NO RINGTONE
• Check cell phone volume of the ringtone
• Check buzzer (connected to buzzer board interface)
• Lift the buzzer connector
• Clean if necessary
• Check for open pattern (lifted pads) from buzzer interface
• Check inductor coil (DCT3)
• Check UI IC /UEM
LOW RINGTONE
• Check cell phone volume of the ringtone
• Check buzzer
• Replace
SLOW RINGTONE
• Check 32.468 kHz crystal oscillator
• Check flash IC
NO VIBRA-MOTOR
• Check cell phone settings for vibration
• Check vibra (connected to vibra board interface)
• Lift the vibra connector
• Clean if necessary
• Check for open pattern from vibra interface (-)
• Board interface to UI IC
• Pin # 16 (-)
• Pin # 1 (+)
• Check UI IC
NO SIGNAL
• Check internal antenna connected to antenna board interface
• Check flash program c/o computer
• Check antenna switch
• Check PA
• Check filters
• Check RF IC & 26 mHz crystal oscillator
• Check audio IC
• Check VCO
• Check power IC
• Check CPU
SIGNAL SETTINGS
Phone settings
Ø Network selection
Ø If no network found
Ø RF IC & 26mHz crystal osdcillator
Ø Audio IC
Ø VCO
Ø if network is found e.g.; globe, smart, sun, do not access PA
• Do not switch on the unit
• Remove battery
• Do not try to charge the unit
• Clean the board using board cleaner
• Dip the board to the ultrasonic solution
• Troubleshoot
• Test battery board interface
• If shortage:
• Check all capacitors & diode
• Pull-out charging IC (test battery terminal)
• Pull-out UI IC (test battery terminal)
• Pull-out PA (test battery terminal)
• Pull-out power IC (test battery terminal)
CONTACT SERVICE
• Check flash program c/o computer
• Reasons for CS
• Cobbha parallel test failed – audio IC
• Ccont parallel test failed -- power IC
• Bad IMEI data - change IEMI number
• MCC PPM check failed - flash program
• EEPROM check failed - eeprom IC
• Flash
HANGUP/AUTO SHUT-OFF
• Check flash program c/o computer
• Check flash IC
• Check audio IC
• Check power IC
• Check CPU
NO POWER
• Check battery pack
• Check battery terminal
• Check power switch
• Check flash program c/o computer
• Check capacitors & diodes
• Check power IC
• Check RF IC & 26mHz crystal oscillator
• Check flash IC / RAM IC
• Check CPU
FLASH RESULTS
DCT 3
• Phone ram is bad - RAM IC
• Unknown flash - flash IC
• Rootsrap begin - power IC
• Reloader err - power IC
• Flash sending loader - flash IC
• Done - RF IC
DCT 4
• 1st boot ok, 2nd boot err - flash IC
• 1st boot err, process failed - flash IC
• 1st boot err, bad resp - can’t conn. UEM
• 1st boot err, bad resp upp - can’t conn CPU
• 1st boot ok, full factory defaults failed - UEM
• 1st boot ok, flash id failed - flash IC
• 1st boot ok, flash complete - good
