Signal Problem

Signal Problem

We are going to discuss here some techniques and steps to repair no signal condition in mobile phones irrespective of brands

hi dear students, sorry for missing last week because there was some problem in our webserver so I could not post new lesson for all of you therefore this is the time to begin again where we lost.

what is signal fault? and what are its kinds?

Signal faults:

signal fault in mobile phones create problem with making connection to our mobile phone tower when we feel that the signal stregnth bars are absent in our mobile phone screen then we can say that our phone has no signal. if signals in mobile phones are absent we cant make a call because there is no connection between our network and our phone that time.

Kinds of Signal fault:

there are many kinds of singal fault but we are discussing here some most common signal faults in mobile phones.

-No signal

-Low signal

-Signal come and then disappear

-signal full or satisfactory but voice cracking

No signal:

dear students now we are going to discuss here some important causes of no signal. if you find a handset with no signal inside it you can consider these components likely to be damaged.

-Antenna

-Antenna pad

-Antenna switch

-antenna tracks

-Rx filters

-Rf Power Amlifier

or tracks

-Rf signal processor (called hagar IC in nokia)

Some time you can experience that signal fault is due to damaged antenna, so you need to replace this antenna specially in sonyericson the antenna is sticker type and it can be easily damaged so you consider first antenna in mobile phone signal faults.

Antenna pad is often rusted with corbon so you can wash it with cleaner like CTC (corbon tatra cloride) this place is often responsible for low signal faults.\

!Antenna switch is the component which is most common in mobile phone signal faults you can locate this component on the top of the mother board it is in steel case often. purpose of this component is to switch between two or some time three type of frequency bands which are (GSM 900MHz , EGSM 1800MHz, PCS 1900MHz ) you may know that there are two types of waves used in our radio section one is TX (wich is transmitted to oythers) second is RX( wich we recieve from others)

antenna swith connects GSM Rx and GSM Tx with antenna pin when it found in GSM based network and in the contrary situation it contacts DCS Rx and DCS Tx pin with antenna pin so may both signal can be communicated.

Antenna tracks are the other reason to no signal so if the contacts between antenna and antenna switch are broken there would be no signal at all.

RX Filters are used to filter incomming radio waves so may no hormonics and other frequencies could get into signal processing only targetted frequency can be enter into the specific place, so some times our RX filters filter frequency we needed as well as other frequencies you can say that they block our targetted frequency so we can replace these filters to get it repaired. this is not in common cases but we found many faults like this in nokia 8210 no signal problem.

the basic thing about radio frequency Power Amplifire is that when we need strong radio waves to spread far around then we have to use some type of amplifire wich wil be able to amlify radio waves in a good power so our mobile phone uses PA(Rf power amplifire) it is used to communicate betweent long distances lik 15-to-20 kilometers so if our PA is damaged it can not comunicate and get response from the base stations.

If the supply of PA is disconnected it cannot work so signal faults can occure so you should check PA +supply carefully.

the main head of the radio department in mobile phone is Rf signal processor which is often used to create, measure, calibrate and manage radio waves so if there is a problem in this signal processor you can say that there will be no signal at all, in some sets you can check they cannot be turned on without radio IC( rf signal processor) like in all nokia mobile phone you cannot power on a set without radio IC except special circumstances.

dear students you have to wait for complete signal faults repairing process which we will discuss in the next lesson