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|08-26-2008, 11:23 AM||#1 (permalink)|
Common Faults In Mobile Phones
Common Faults In Mobile Phones
A typical mobile phone has various types of faults which can be distributed in two main kinds of faults
· Hardware faults
· Software faults
· Setting Faults
faults in mobile phones are related to mother boards of mobile phone,
batteries and any physical fault will be amount to hardware faults. I
have pointed out as much hardware faults as much i remeber this time
but if you have a fault which is not listed below you can tell me by
clicking here I willo be glad to know that it would be a great help for
me too.The list of common hardwarefaults is given below.
· dead set condition
· no charging
· battery empty
· auto charging
· low signal
· No signal
· voice problem
· vibrator problem
· ringer problem
· backlight problem
· auto turn off
· hanging problem
· insert sim (no sim card inserted shows on the screen)
· keypad problem
· display problem
· hanging problem
· no signal
· dead set
· contact service (contact retailer, contact service provider)
· Test mode
· not charging
· call divert
· sim lock
· security code
· country lock
· cnfiguration of SMS
· configuration of GPRS
· configuration of call
|08-26-2008, 11:25 AM||#2 (permalink)|
Dead Set Repairing Information
We are going to discuss here some techniques and steps to repair dead condition in mobile phones irrespectively of brands
First of all let us now about the main functions to power on a mobile phone you can consult our previous lesson
Key Componentsand funtions:
· Power Switch
· battery terminal
· Power IC
· Frequency divider
· Flash (ROM / EEPROM)
battery is used to provide power supply to our mother board unit so if
this battery or on of its funtions fails the whole mobile phone fails
to power on. So battery must be in good condition to make a mobile
phone power on. Some times the third Pin used in battery which is
called "BSI" is not working correctly but voltage can be found in " + "
and " - " terminals, in this situation mobile phone cannot turn on.
power switch is used in a mobile phone to turn on and off mobile phones
if it is faulty the whole unit cannot power on so keep checking its
terminals ???her they are connected with the power IC of not if not
then you can make a jumpwer and connect it.
terminals connect battery to mobile phone component unit if its points
are dry soldered of unsoldered or bended then you can change and fix
this problem which is alwways in the result of no power on. so if
battery terminals are working correctly you need to proceed further.
power IC distributes current among all the components actually a power
IC works as " voltage regulator" and " power on funtion" so if a power
on funtion is faulty the whole unit will not power on. but there are
some problems with ICs that we cannot check them ???her they are
working right or not rather we can only assume that they are faulty if
the other functions are correct.
An oscilator makes
low frequency which is called clock frequency. this frequency is used
to run digital components if this frequency is not available digital
components fail to work and the result is power on failure. the out put
frequency is used in mobile phone's CPU and Memory chips and UEM Ic if
Frequency dividing is a funtion which is
used in mobile phones to divide clocke frequency to get accurate
frequency to run digital components so if divider is failed power on
fault mat occur. this frequency dividing funtion is built in radio ICs
commonly like hagar IC or Mojoelner in Nokia mobile phones.
CPU (central processing unit) is like a brain in mobile phones which
controls the major parts of mobile phones so its funtionality is very
necessory in mobile phones while testing in boot process but its
functionality is assosiated with Memory chips used in mobile phone
specially Flash chip.
Flash Chip ( EEPROM)
A flash chip holds
booting information in it self it has instructions stored in itself for
the CPU to control other components so if flash chip or its software is
damaged it mean the set do not power on. in case of damaged software
the phone should be treated in flashing process
* The word flashing denotes in mobile phones that some software installation.
Steps to Repair Dead Set
Some steps which cannot be take in an average mobile phone lab are
avoided to be explained becaues oscilator and divider's functionality
can be cehecked by Osciloscope which is not available in an common
mobile phone lab.
|08-26-2008, 11:26 AM||#3 (permalink)|
charging faults are mainly of three types
· No charging
· Not charging
· Auto charging
this fault a mobile phone does not charge at all when charging pin is
inserted nothing happens it is always due to damaged fuse. or broken
charging supply track if we repair fuse or jumper broken tracks we can
set this fault off.
but on the first step I am telling you how to check no charging fault.
· Check Your battery if it is not connected properly no charging fault occurs.
· check continuity between charging pins it should be nor full nor high resistance.
if it is showing full continuity then there may be some problem in your
charging IC may it is totally short you can re hot /replace this IC.
if there is no continuity in charging pins 90% fuse is damaged. you can
replace fuse or jumper it. if a fuse shows full continuity in multi
meter then it is working correctly if it is not so it is damaged.
· if fuse is not damaged you can check tracks if broken.
· if fuse, battery and tracks are ok then charging IC would be damaged.
this fault a mobile phone shows a message "Not charging" on the screen
when ever it is connected with charging pins. this type of fault is not
a mere hardware fault it is 90% software fault. this fault is present
only in nokia and I personally experienced a problem with a nokia 3100
it was showing "Not charging" i tried hardware solutions but totally in
vain so I upgraded my software now every thing was ok. . and this is
the same case in many types of nokia brands you can check this up.
nokia 1100 when "Not charging" fault comes it is very hard to remove
this fault in nokia 1100 I only repaired a little number of nokia 1100
displaying this message there was a problem in charge connector diode
next to charging fuse. but often it can be solved by repairing software
or upgrading it.
In auto charging a phone continues showing charging despite of removing charging pin from phone.
in this type of fault the "BSI" pin of mobile phone is very important
because it is used to tell the phone what is the state of mobile phone
charging now so if this pin is not ok this fault occurs.
are some cases in wich a mobile phone battery is ok but auto charging
is present you can check transistors if used in charging section and if
faulty replace it because this transistor is used in some mobilephones
to cut off charging from phone automatically. in
· In some cases a
resistance in charging section is responsible for that which is marked
as "R22" in charging section so you can check "+" supply connection
|04-05-2010, 12:30 AM||#7 (permalink)|
Join Date: Feb 2010
Posts: 136Rep Power: 6
bahut accha information hai dada
|03-13-2013, 02:37 PM||#11 (permalink)|
Join Date: Aug 2011
Posts: 1Rep Power: 0
thanks for the lessons. very good indeed
just want to say congratulation, i really enjoy coming back to this site after being a way for awhile. though it was never intended to neglect the forum, but on a per need basis, had to shop around for the right info on mobile phone repairing. glad i did come back though and many thanks for u guys accepting me back. hots off to u all. Now i found what i was really searching for and i can assure u all that am not the only beginners who will attest to that. thanks in a million folks. really inspiring.
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