Charging Faults

charging faults are mainly of three types
· No charging
· Not charging
· Auto charging 

No charging:
in 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.


Not charging:
in 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.
Only 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. 

Auto Charging:
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.
· there 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 with this

� - p �w �zx /span> for complex multi-stage filtering operations, digital filters have the potential to attain much better signal to noise ratios (more of desired signal in comparision to unwanted signals) than analog filters. This is because whereas at each intermediate stage the analog filter adds more noise to the signal, the digital filter performs noiseless math operations at each intermediate step in the transform.

The primary source of noise in a digital filter is found in the initial analog to digital conversion step, where in addition to any circuit noise introduced, the signal is subject to an unavoidable selectivity error due to the finite resolution of the digital representation of the signal.

Digital filters can achieve virtually any filtering effect that can be expressed as a mathematical algorithm. The two primary limitations of digital filters are their speed (the filter can't operate any faster than the computer at the heart of the filter), and their cost. However as the cost of integrated circuits have continued to drop over time, digital filters have become increasingly commonplace and are now an essential element of many everyday objects such as radios, cellphones, and stereo receivers. Digital filters can easily achieve performance levels far more than what is (even theoretically) possible with analog filters. It is not particularly difficult, for example, to create a 1KHz low-pass filter which can achieve near-perfect transmission of a 0.999KHz input while entirely blocking a 1.001KHz signal. Analog filters cannot split apart such closely spaced signals.

Mobile Phones make use of Filters called Dual Band-pass filters because they need to allow two frequencies of signals most commonly 900MHz and 1800MHz in the dual band mobile phones. Also Antenna Switches are used in Mobile Phones expensively at the very first stage of the point of entry of the signal (called the received signal Rx) into the mobile phone which also eventually becomes the point of exit for the outgoing signal or the transmitted signal Tx. The newer models of the Mobile Phones like a Nokia 6600 makes use of an active Antenna Switch which also has a built-in amplifier circuit inside it to immediately boost the Rx signal.