I prepare to used the Nokia Mobile Phone as a set example of this lesson, for Nokia is the most efficient mobile phone to fix for which they provide all source of service manuals and diagrams aside from other mobile phone products on the planet today.
Basically there are many types of charging problems not just in Nokia Handset but all mobile phones products like Samsung,LG,Sony Ericsson, Motorola,iPhone, Blackberry and etc.
Not Charging - When the charger is being plug-in and it shows the word on the display "Not Charging"
Charger Not Supported some sort of like the charger is not compatible with the handset but the problem actually exist on the charging circuit.
No Response - this is what this problem called when even a good and working charger is being plug-in, The handset shows no response or no reaction when the charger is being plug-in.
Fake Charging - The handset is charging by itself even without any charger plug unto it, or the indicator shows that the handset is charging when the charger plug unto it but the battery haven't not charge any voltage or current at all.
Invalid Charger- The handset responds that the charger is invalid and not compatible with the handset.
Those Charging problem issues mentioned above were just common types of faulty charging circuits within any various mobile phone handsets exist before and nowadays.
Experts and Professional Technician have different techniques when it comes to troubleshoot such problems. But mostly all of them start on the basic method on how to find the faulty component or parts within that certain problem.
Now, typically mostly hardware troubleshooters starts within this following methods below.
1. Checking up the charger if the charger is good, weak or being damaged, or try to use other good and working charger to compare if the charging problem still exist.
The picture below is a typical layout of a common mobile phone charger. It converts the AC (Alternating Current)voltage coming from an outlet then convert it into a DC voltage. It has "+" positive and "-" negative polarity. A common mobile phone charger range from 4.5 to 6 volts DC(Direct Current)
Various mobile phone products charger have different types of pin connectors layout and packaging but the operational circuit took inside it almost all the same.
Checking up the battery if it is still working or weak and test its Voltage and currents or replace with a good and working one.
3. Checking up the Charging Pin Connector by visualization and see to it for some breakage or some dust and dirt corrosion. Corrosive element such moisture may also cause the problem and see to it that is clean and free of any corrosive objects.
4. Checking up the Charging Terminal Contact Pads if it is free from any dust and dirt and making sure that it is totally clean.
5. Then Proceed to Component Fault Finding Method if found that the earlier mentioned above was all fine but the problem still exist.
In component fault finding method it is also advice to start from the basic test and check up procedures on every components within a certain circuits area. There are so many free and shared solutions scattered away among so many gsm forum communities. Some of them were pictures of jumpers and modification methods and lack of step by step procedure instructions, it is because those certain solutions were belong to all exactly understand the whole circuitry and not for the beginners. That is why only those masters and experts alike only can catch up what was that all about.
But not always happens like that, there are also many experts that always think the benefit of the new learners which he emphasized some step by step procedure on where to start to troubleshoot or test.
In continuation of this lesson I prepare here the basic Understanding of Mobile Phones Charging Circuit for Beginners.