Mobile phone repair knowledge and skills
Mobile was able to call back because it has a huge system that supports it. In China, analog phones or an analog network, said ETACS system, GSM digital mobile phone is a GSM digital network or a known GSM system. Analog ETACS system each channel has a different frequency, when the base station signal, indicating a mobile phone transmitter specified frequency to a network, the user will take this one channel, other users can not occupy the same channel a; GSM system TDMA is used in site selection method, the same frequency channel is divided into eight time slots, you can at different times occupied by the different users, each user assigned signal between the base station to distinguish between a certain protocol. This makes more complex the structure of GSM mobile phone, a stronger anti-interference ability.
Voice signal, also known as voice signals. The frequency of the speech signal is usually between 300 ~ 3400Hz, to load it into a pulse signal transmitted in the carrier, the first voice signal to the low-frequency sampling, quantization. Sampling is A / D conversion technology used, as shown in Figure 1. Analog signal is a continuous sine or cosine waves, a series of pulse signals to use the basic undistorted reproduction of it, then the sampling frequency should be high enough so that the signal can be restored. According to the law of sampling, sampling frequency should be twice as large a sample frequency equal to no distortion. In the current digital phones, the sampling frequency of use of 8kHz, the sampling rate is sufficient to guarantee the credibility of the signal. Digital pulse signal only 0 and 1 two. After sampling after the pulse, the amplitude of some small, to an accurate description of pulse wave, we must have it the “height” has a definition, this is the quantization process. Each sample value encoded as 8bit code form for the 8k × 8bit / s = 64kbit / s signal. This is the voice signals into digital signals the first step, the analog / digital converter (A / D). However, 64kbit / s share of band signal is too wide, no doubt is a waste. Therefore, the signal is compressed, through the voice compression technology will 64kbit / s signal into a 13kbit / s signal, saving the band. From a sample of this series to quantify the compression process, called the speech coding.
Speech coding, we get a set of coherent information reflects the voice 13kbit / s pulse signal, the set of signals will be re-grouping, factoring out the important bit code, time code and least important bit bit code, and then they do not sequence inserted into the code base, which is partitioned into. Why? Because the wireless signal transmission in the air will encounter all kinds of interference, and these disturbances are random. If the speech codec sent 13kbit / s signal in turn transmit the load to the carrier instead of re-combination between the insertion points, then the disruption of a period of time when this period of time will result in the loss of all data, In the absence of relevant information during this time, it is impossible for the resumption of these signals. The use of the technology is inserted between points, even if the information is destroyed over time, it is only a voice in a small part of the group is destroyed, according to other burst can recover it.
Of course, restoration of damaged according to the relevant pulse pulse, is the need by adding some coding to identify the symbol. This encoding can be added block convolutional codes, error correction code and parity code of several forms to achieve. The process described above, that is, channel coding and interleaving process.
GSM mobile phone than ETACS a very advanced technology that greatly enhanced its confidentiality. GSM phone encryption to a variety of ways, such as registration of the phone is switched network, the IMSI number to send and MIN number and other unique network number for each user, the number sent in the air to go through a SIM card is stored in the value of ki operation, this operation corresponds with the switch, so to get in the air and cracked this information is basically impossible. In addition, GSM system also has the function of frequency hopping. As the name suggests, is changing the frequency of the carrier frequency in order to protect the information role of being stolen. This process, called encryption.
After more than a series of speech signal processing, they form a Burst, the frame signal. 0.3 Gaussian Minimum Shift-pass frequency detector control that 0.3GMSK technology to transform binary data into a frequency modulated signal, which it loads to the carrier in the form of electromagnetic waves sent out, this is the modulation process.
意义在于，有了概括的印象，对手机硬件部分各个集成块的作用就会比较明确，有利于维修时对故障起因的” onmouseout=”this.style.backgroundColor=’#fff’”>GSM mobile phone, a general description of speech coding, which for the maintenance of the actual </ SPAN> significance lies, with the general impression on the phone all the hardware part of the role will be more clearly integrated block is conducive to the cause of the fault repair determination.
SIM card of knowledge
GSM mobile phone SIM card is a symbol of the unique user identity. Its advantage is that you do not need to bring digital mobile phone network. Happy day you suddenly want to try it, global communication, is very simple, you can go to any of the telecommunications sector in the consignment outlets to choose a number you like, turn in the money, the dealers give you the SIM cassette home, bought into the phone whenever you can use the. The second advantage is the day you need to call on the road, but why are cell phone battery is dead, and then, you can borrow his cell phone passers (Note that if by phone), will be his own card out, put your own SIM card, that is: when you use your own number, calls are recorded entirely in your own head. Besides saying “thank you” outside, you do not feel owed a debt.
So, SIM card, which features in the end with its principle of how it? The following is a brief description.
SIM card is a status symbol as a user, mainly contains the following two types of information: IMSI number and the authentication, encryption algorithm.
IMSI International Mobile Station No. The full name of the user identification number, and IMEI International Mobile Equipment Identity number is two totally different concepts. IMSI SIM card number is fixed in the internal memory chip number. When the client application network, the telecommunications operator who brought a new free SIM card, the card marked 15 IMSI number, corresponding to the number recorded in the user selection of data input into the computer create the file. This is the system convenient and efficient way to network.
IMEI number is a cell phone inside the fuselage of a number of inherent reaction to this mobile phone factory, affiliated companies and a series of information.
These two numbers reflects the GSM system, the different machines, the principle of separation numbers.
GSM system has a good privacy is also reflected in the SIM card. Internet phone user, you need to send IMSI number in the air for authentication. IMSI number is transmitted in the air after a SIM card authentication, encryption algorithms to be sent. Through these complex operations, is basically impossible to decipher. This is better than the GSM system, a major embodiment ETACS system.
From the exterior view, SIM card, large and small card, and it was to meet the needs of different mobile phones are designed in different sizes. But with the growing mobile phone market, small, lightweight trend, more and more companies out of the kcal model, a small card more and more popular.
There are two SIM card, power supply: 5V and 3V. The SIM card is usually an early 5V supply. With the requirements of the battery become longer, manufacturers adopted a variety of techniques to reduce electricity use mobile phones, including CPU power from the 5V down to 3V or so around the whole body along with the power supply mobile phone also generally reduced to V, so that the supply voltage drop SIM card also imperative. Currently, many SIM cards can be compatible with both voltage power supply, which is to meet the needs of the transitional period.
In addition, SIM card capacity is not the same, depending on the SIM card memory capacity of internal memory chip size. Reflected in the capacity of the card features the user when using the phone book to the SIM card, how many records exist.
In daily use, sometimes “SIM card not accepted”, “Please insert SIM card” which is a normal phenomenon. At this time, we can remove the SIM card from the machine, gently skimming with a rubber surface. Things must not scratch card with a sharp face, so as to avoid uneven foot card bad touch, or even completely damaged SIM card. If still not work properly after cleaning, you should connect your phone card to a professional maintenance, so that maintenance personnel check.
3: Maintenance Starter
Phone is a sophisticated high-tech products, compared with TV, VCD machines and even computer have higher levels of integration. It is usually by the Board (including the logic board and RF board), key board, display, housing and the antenna of several parts. Motherboards are generally plywood, including the power plane layer and a layer of the common negative (ie formation). These characteristics of mobile phones, we must not in the maintenance of electronic products in general to look at, must be carefully and conscientiously, and have strict standards to ensure the quality of maintenance to prevent fatal damage to the phone.
Summarizes several years of maintenance experience, maintenance procedures and treatment methods will now be described below, for your reference.
Observed
What is the observation of it? A fault cell phone in your hand, first we carefully identified the naked eye. Users are not always clearly state their reasons for mobile phone failure, it is critical to identify the source of their disease. This can often play a multiplier role.
Observed, not only to disassemble check the status of plate, scratches on the casing, but also very sensitive to deformation. Sometimes, the direction of a cell phone as a violent impact, causes sheet position of components within the relevant moment of rupture, no iron or heat gun to heat these components are often unable to identify them. However, if carefully observed case. Or you can see parts of the deformation of the impact from the deflection board to find the relevant location often take many detours to avoid. Another example is the mobile water, the failure of these phones are often a bit confusing, no rules to follow, but if look carefully, find out the corrosion point, you can quickly rule out the “cause”
As a mature brand of mobile phone, its appearance and have some basis for the design of the motherboard is basically reasonable. To learn to observe, we must first have a basic understanding of mobile phones. Mobile phone shell is smooth and there is a certain, shiny, no scratches or uneven. Phone connection between the antenna and the fuselage is appropriateness, generally no major irregularities or large rotating. Board is a major component of mobile phones, the arrangement of components on the motherboard is very neat, very clean and neat solder joints, solder evenly distributed. Looking entire board formation rules, in the light to see some slightly transparent, you can see the middle of the plywood.
With the general understanding of the above, let us look at the Central Standing Committee routine maintenance problems.
Water machine
Serious water mobile phone is easy to see out. From the outside may have the following phenomenon: the shell was wet; show your home has water droplets or mist; battery touch the feet of green fixtures (which is caused by corrosion); the back post after a float shell , unlike the formation of a good machine as the back post. Of course, this is the initial appearance as a judge, found to be more precise, you need to disassemble test.
Check the motherboard, the following points for reference:
① many serious water cell phone, there is significant water damage on the motherboard, usually located in the display at or headphones, microphone (plastic cap wet). If you enter the water, you may see a small piece of board best way to end plasma like dirt.
② The longer the water inlet track dried the phone, you can glance look at the foot of the manifold, if the pin can be sure no glossy dark gray machine into the water. Sometimes not all the manifold will appear dark color pins, only a few individual black spot, we can thus determine the aircraft into the water.
③ many models because of the design’s sake, the water will cause people easily assembled water under the liver in the display, such as Ericsson, 337,388 mobile phones, the Nokia 3810 mobile phone, Mo-1DR01A 8200 phone. These types of displays connected by plug-in models, are vulnerable to the contact surface of the display and motherboard retention of water, causing corrosion or plug disconnected components.
④ There was a time, major mobile phone manufacturers introduced models of RF part of the circuit board or logic board, are cloth covered a large area of the screen to be shielded to prevent interference between signals, – but it adds to the maintenance of certain difficult. Some small amount of water into the cell phone, but why would gather water in the shield cap. Therefore, maintenance of mobile phones, we must carefully patience.
Must be pointed out is this: When you suspect there may be a cell phone water machine, it should immediately remove the battery to prevent short circuit inside, expanding fault surface, must not try test.
Of course, for any one vendor, they are not recommended Weixiu water cell phone, because the water machine after the repair there are many latent failures, which will directly result in failure rates rise, and even make some unclear to users this model into question. Therefore, the maintenance department, the water machine maintenance is a certain risk, we must be cautious, when necessary, first the user instructions.
Broken machine
Cell phones are portable items, was wrestling in the daily, is common to be touched, but fall touch to varying degrees, the damage degree of difference in terminology. Broken cell phone usually have some marks in appearance, such as scratches on the casing, screen scratches, broken shell, flip the fracture, the deformation of the foot touch the battery, antenna deformation and so on.
For the broken cell phone, you can first test machine to test mobile phone in what is a problem, the case of handset failure, flip failure, or the phone is not on the electricity. Failure as the handset, a microphone failure, failure of such flip is better to deal with mechanical problems, and check the relevant parts of the welding is normal, or replace the appropriate parts, generally can be solved.
But for the fall touch circuits caused the failure to take a step by step test signal to determine the components of the damage. Components are most easily broken crystal, and various filters. Detailed in this temporarily, the relevant issues in the future to be introduced.
Informal channels, mobile phone or assembling machines
Strictly speaking, the parallel phone not that shoddy products, but a smuggling goods to avoid customs duties. Of these phones, as long as the new machine, the quality of down is not a problem. This is not to encourage users to buy smuggled goods, not to mention the national interests of the self. Of interests, on one hand, you can not be sure whether to buy the phone manipulated. Because the phone’s battery a cradle of these parts is strictly required, for the sake of greater profits, many vendors operating Fortunately, the private machine, excellent charge will be accessories to the poor, is still not easy in the current test case of genuine accessories , cheap anti-user greedy moment suffer heavy losses (original accessories and the inferior parts are often the difference in price several hundred dollars.) On the other hand, and buy the original machine, but as a parallel, it is definitely not enjoy all the vendors to the user’s warranty policy. Furthermore, the current mobile phone market has been fully liberalized, the price transparency, quality, competition, after-sales service system has been formed, each big company has carried out large-scale publicity and seminars after-sales service, users will gradually experience the purchase of regular mobile phone superiority.
Then, as the service sector, identify the source of mobile phones is also very necessary.
In order to regulate the current mobile phone market, the National Industry Management Office issued a year out of the provisions of the sources of mobile phones and accessories, specifications, and nominal have been explicit. Where, within the scope of the license to operate mobile phones, after the machine shell are labeled with “network license” sign, and a bar code. Our maintenance staff, in addition to the simple recognition, but also with other recognition.
First of all, to tell the phone case. Assembled machine in order to save money, often not using the original chassis. In case the black color on the original machine is dark black, not reflective; rather than the original shell is black though, but the smooth surface will be reflective, the black is a black, not polished grainy. If the color of the case, the original shell is also not reflective, there is a polished grainy, deep colors have intensity; rather than the original chassis smooth, reflective, making the color too bright glare, appears to grade is not high enough. Shell color that is often difficult to distinguish between mobile phones, but as long as we compare the color change and transition, is also able to separate the. General original color shell from a different angle, looking at the light will show different colors, and the particles are polished management. And appears thick, and the color change of natural harmony; non-original case is showing no depth is too bright, color dull. But now many of assembling machine in order to deceive customers, often buy original case packaging, so we have to check the next step.
After identifying label case is very important. In addition to licensing the shell after the network card industry, there is a cell phone before leaving the factory each product must be affixed to prove. In the back paste this, marked with the following items:
① IMEI number, the mobile phone device identification code is formed by the 15 digit number.
The IMEI number of each phone is definitely not the same, it represents the identity of a cell phone, curing the chip in the machine on board is not free replacement. In some countries mobile communication system, in order to protect the legitimate interests of users, the system will drive a digital phone number and IMEI number checked simultaneously. Say, if your phone was stolen a number, he used his mobile phone SIM card coupled with your use of the system is not recognized, that he is not available. And you only need to fix your behalf on a number of the SIM card on it. This will protect the legitimate interests of users. Of course, if you have both lost your cell phone and SIM card, which requires the department to apply for business downtime or re-purchase a SIM card, business, and you also need to buy a digital mobile phone.
Examination IMEI number and mobile phone shell read the IMEI number is the same, is the most direct way to determine whether the phone an important tool for the assembly machine. IMEI read in the machine is simple: Replace the battery, boot, turn on the keyboard typing * # 06 #, you will see on the screen body this phone number (ie IMEI number). But M0TOR0LA’s 8200,7200 and other early products, in this way can not see the IMEI number, need special testing card (TEST CARD). Use as follows: the same as the installed SIM card into the test card from Jianpanshangqiao into the # key, enter the test state, knocking on people * # 06 #, read the IMEI number, and the back cover quote on the IMEI number back comparison. IMEI number, but not to say that certainly is not the same assembly machine
Mobile was able to call back because it has a huge system that supports it. In China, analog phones or an analog network, said ETACS system, GSM digital mobile phone is a GSM digital network or a known GSM system. Analog ETACS system each channel has a different frequency, when the base station signal, indicating a mobile phone transmitter specified frequency to a network, the user will take this one channel, other users can not occupy the same channel a; GSM system TDMA is used in site selection method, the same frequency channel is divided into eight time slots, you can at different times occupied by the different users, each user assigned signal between the base station to distinguish between a certain protocol. This makes more complex the structure of GSM mobile phone, a stronger anti-interference ability.
Voice signal, also known as voice signals. The frequency of the speech signal is usually between 300 ~ 3400Hz, to load it into a pulse signal transmitted in the carrier, the first voice signal to the low-frequency sampling, quantization. Sampling is A / D conversion technology used, as shown in Figure 1. Analog signal is a continuous sine or cosine waves, a series of pulse signals to use the basic undistorted reproduction of it, then the sampling frequency should be high enough so that the signal can be restored. According to the law of sampling, sampling frequency should be twice as large a sample frequency equal to no distortion. In the current digital phones, the sampling frequency of use of 8kHz, the sampling rate is sufficient to guarantee the credibility of the signal. Digital pulse signal only 0 and 1 two. After sampling after the pulse, the amplitude of some small, to an accurate description of pulse wave, we must have it the “height” has a definition, this is the quantization process. Each sample value encoded as 8bit code form for the 8k × 8bit / s = 64kbit / s signal. This is the voice signals into digital signals the first step, the analog / digital converter (A / D). However, 64kbit / s share of band signal is too wide, no doubt is a waste. Therefore, the signal is compressed, through the voice compression technology will 64kbit / s signal into a 13kbit / s signal, saving the band. From a sample of this series to quantify the compression process, called the speech coding.
Speech coding, we get a set of coherent information reflects the voice 13kbit / s pulse signal, the set of signals will be re-grouping, factoring out the important bit code, time code and least important bit bit code, and then they do not sequence inserted into the code base, which is partitioned into. Why? Because the wireless signal transmission in the air will encounter all kinds of interference, and these disturbances are random. If the speech codec sent 13kbit / s signal in turn transmit the load to the carrier instead of re-combination between the insertion points, then the disruption of a period of time when this period of time will result in the loss of all data, In the absence of relevant information during this time, it is impossible for the resumption of these signals. The use of the technology is inserted between points, even if the information is destroyed over time, it is only a voice in a small part of the group is destroyed, according to other burst can recover it.
Of course, restoration of damaged according to the relevant pulse pulse, is the need by adding some coding to identify the symbol. This encoding can be added block convolutional codes, error correction code and parity code of several forms to achieve. The process described above, that is, channel coding and interleaving process.
GSM mobile phone than ETACS a very advanced technology that greatly enhanced its confidentiality. GSM phone encryption to a variety of ways, such as registration of the phone is switched network, the IMSI number to send and MIN number and other unique network number for each user, the number sent in the air to go through a SIM card is stored in the value of ki operation, this operation corresponds with the switch, so to get in the air and cracked this information is basically impossible. In addition, GSM system also has the function of frequency hopping. As the name suggests, is changing the frequency of the carrier frequency in order to protect the information role of being stolen. This process, called encryption.
After more than a series of speech signal processing, they form a Burst, the frame signal. 0.3 Gaussian Minimum Shift-pass frequency detector control that 0.3GMSK technology to transform binary data into a frequency modulated signal, which it loads to the carrier in the form of electromagnetic waves sent out, this is the modulation process.
意义在于，有了概括的印象，对手机硬件部分各个集成块的作用就会比较明确，有利于维修时对故障起因的” onmouseout=”this.style.backgroundColor=’#fff’”>GSM mobile phone, a general description of speech coding, which for the maintenance of the actual </ SPAN> significance lies, with the general impression on the phone all the hardware part of the role will be more clearly integrated block is conducive to the cause of the fault repair determination.
SIM card of knowledge
GSM mobile phone SIM card is a symbol of the unique user identity. Its advantage is that you do not need to bring digital mobile phone network. Happy day you suddenly want to try it, global communication, is very simple, you can go to any of the telecommunications sector in the consignment outlets to choose a number you like, turn in the money, the dealers give you the SIM cassette home, bought into the phone whenever you can use the. The second advantage is the day you need to call on the road, but why are cell phone battery is dead, and then, you can borrow his cell phone passers (Note that if by phone), will be his own card out, put your own SIM card, that is: when you use your own number, calls are recorded entirely in your own head. Besides saying “thank you” outside, you do not feel owed a debt.
So, SIM card, which features in the end with its principle of how it? The following is a brief description.
SIM card is a status symbol as a user, mainly contains the following two types of information: IMSI number and the authentication, encryption algorithm.
IMSI International Mobile Station No. The full name of the user identification number, and IMEI International Mobile Equipment Identity number is two totally different concepts. IMSI SIM card number is fixed in the internal memory chip number. When the client application network, the telecommunications operator who brought a new free SIM card, the card marked 15 IMSI number, corresponding to the number recorded in the user selection of data input into the computer create the file. This is the system convenient and efficient way to network.
IMEI number is a cell phone inside the fuselage of a number of inherent reaction to this mobile phone factory, affiliated companies and a series of information.
These two numbers reflects the GSM system, the different machines, the principle of separation numbers.
GSM system has a good privacy is also reflected in the SIM card. Internet phone user, you need to send IMSI number in the air for authentication. IMSI number is transmitted in the air after a SIM card authentication, encryption algorithms to be sent. Through these complex operations, is basically impossible to decipher. This is better than the GSM system, a major embodiment ETACS system.
From the exterior view, SIM card, large and small card, and it was to meet the needs of different mobile phones are designed in different sizes. But with the growing mobile phone market, small, lightweight trend, more and more companies out of the kcal model, a small card more and more popular.
There are two SIM card, power supply: 5V and 3V. The SIM card is usually an early 5V supply. With the requirements of the battery become longer, manufacturers adopted a variety of techniques to reduce electricity use mobile phones, including CPU power from the 5V down to 3V or so around the whole body along with the power supply mobile phone also generally reduced to V, so that the supply voltage drop SIM card also imperative. Currently, many SIM cards can be compatible with both voltage power supply, which is to meet the needs of the transitional period.
In addition, SIM card capacity is not the same, depending on the SIM card memory capacity of internal memory chip size. Reflected in the capacity of the card features the user when using the phone book to the SIM card, how many records exist.
In daily use, sometimes “SIM card not accepted”, “Please insert SIM card” which is a normal phenomenon. At this time, we can remove the SIM card from the machine, gently skimming with a rubber surface. Things must not scratch card with a sharp face, so as to avoid uneven foot card bad touch, or even completely damaged SIM card. If still not work properly after cleaning, you should connect your phone card to a professional maintenance, so that maintenance personnel check.
3: Maintenance Starter
Phone is a sophisticated high-tech products, compared with TV, VCD machines and even computer have higher levels of integration. It is usually by the Board (including the logic board and RF board), key board, display, housing and the antenna of several parts. Motherboards are generally plywood, including the power plane layer and a layer of the common negative (ie formation). These characteristics of mobile phones, we must not in the maintenance of electronic products in general to look at, must be carefully and conscientiously, and have strict standards to ensure the quality of maintenance to prevent fatal damage to the phone.
Summarizes several years of maintenance experience, maintenance procedures and treatment methods will now be described below, for your reference.
Observed
What is the observation of it? A fault cell phone in your hand, first we carefully identified the naked eye. Users are not always clearly state their reasons for mobile phone failure, it is critical to identify the source of their disease. This can often play a multiplier role.
Observed, not only to disassemble check the status of plate, scratches on the casing, but also very sensitive to deformation. Sometimes, the direction of a cell phone as a violent impact, causes sheet position of components within the relevant moment of rupture, no iron or heat gun to heat these components are often unable to identify them. However, if carefully observed case. Or you can see parts of the deformation of the impact from the deflection board to find the relevant location often take many detours to avoid. Another example is the mobile water, the failure of these phones are often a bit confusing, no rules to follow, but if look carefully, find out the corrosion point, you can quickly rule out the “cause”
As a mature brand of mobile phone, its appearance and have some basis for the design of the motherboard is basically reasonable. To learn to observe, we must first have a basic understanding of mobile phones. Mobile phone shell is smooth and there is a certain, shiny, no scratches or uneven. Phone connection between the antenna and the fuselage is appropriateness, generally no major irregularities or large rotating. Board is a major component of mobile phones, the arrangement of components on the motherboard is very neat, very clean and neat solder joints, solder evenly distributed. Looking entire board formation rules, in the light to see some slightly transparent, you can see the middle of the plywood.
With the general understanding of the above, let us look at the Central Standing Committee routine maintenance problems.
Water machine
Serious water mobile phone is easy to see out. From the outside may have the following phenomenon: the shell was wet; show your home has water droplets or mist; battery touch the feet of green fixtures (which is caused by corrosion); the back post after a float shell , unlike the formation of a good machine as the back post. Of course, this is the initial appearance as a judge, found to be more precise, you need to disassemble test.
Check the motherboard, the following points for reference:
① many serious water cell phone, there is significant water damage on the motherboard, usually located in the display at or headphones, microphone (plastic cap wet). If you enter the water, you may see a small piece of board best way to end plasma like dirt.
② The longer the water inlet track dried the phone, you can glance look at the foot of the manifold, if the pin can be sure no glossy dark gray machine into the water. Sometimes not all the manifold will appear dark color pins, only a few individual black spot, we can thus determine the aircraft into the water.
③ many models because of the design’s sake, the water will cause people easily assembled water under the liver in the display, such as Ericsson, 337,388 mobile phones, the Nokia 3810 mobile phone, Mo-1DR01A 8200 phone. These types of displays connected by plug-in models, are vulnerable to the contact surface of the display and motherboard retention of water, causing corrosion or plug disconnected components.
④ There was a time, major mobile phone manufacturers introduced models of RF part of the circuit board or logic board, are cloth covered a large area of the screen to be shielded to prevent interference between signals, – but it adds to the maintenance of certain difficult. Some small amount of water into the cell phone, but why would gather water in the shield cap. Therefore, maintenance of mobile phones, we must carefully patience.
Must be pointed out is this: When you suspect there may be a cell phone water machine, it should immediately remove the battery to prevent short circuit inside, expanding fault surface, must not try test.
Of course, for any one vendor, they are not recommended Weixiu water cell phone, because the water machine after the repair there are many latent failures, which will directly result in failure rates rise, and even make some unclear to users this model into question. Therefore, the maintenance department, the water machine maintenance is a certain risk, we must be cautious, when necessary, first the user instructions.
Broken machine
Cell phones are portable items, was wrestling in the daily, is common to be touched, but fall touch to varying degrees, the damage degree of difference in terminology. Broken cell phone usually have some marks in appearance, such as scratches on the casing, screen scratches, broken shell, flip the fracture, the deformation of the foot touch the battery, antenna deformation and so on.
For the broken cell phone, you can first test machine to test mobile phone in what is a problem, the case of handset failure, flip failure, or the phone is not on the electricity. Failure as the handset, a microphone failure, failure of such flip is better to deal with mechanical problems, and check the relevant parts of the welding is normal, or replace the appropriate parts, generally can be solved.
But for the fall touch circuits caused the failure to take a step by step test signal to determine the components of the damage. Components are most easily broken crystal, and various filters. Detailed in this temporarily, the relevant issues in the future to be introduced.
Informal channels, mobile phone or assembling machines
Strictly speaking, the parallel phone not that shoddy products, but a smuggling goods to avoid customs duties. Of these phones, as long as the new machine, the quality of down is not a problem. This is not to encourage users to buy smuggled goods, not to mention the national interests of the self. Of interests, on one hand, you can not be sure whether to buy the phone manipulated. Because the phone’s battery a cradle of these parts is strictly required, for the sake of greater profits, many vendors operating Fortunately, the private machine, excellent charge will be accessories to the poor, is still not easy in the current test case of genuine accessories , cheap anti-user greedy moment suffer heavy losses (original accessories and the inferior parts are often the difference in price several hundred dollars.) On the other hand, and buy the original machine, but as a parallel, it is definitely not enjoy all the vendors to the user’s warranty policy. Furthermore, the current mobile phone market has been fully liberalized, the price transparency, quality, competition, after-sales service system has been formed, each big company has carried out large-scale publicity and seminars after-sales service, users will gradually experience the purchase of regular mobile phone superiority.
Then, as the service sector, identify the source of mobile phones is also very necessary.
In order to regulate the current mobile phone market, the National Industry Management Office issued a year out of the provisions of the sources of mobile phones and accessories, specifications, and nominal have been explicit. Where, within the scope of the license to operate mobile phones, after the machine shell are labeled with “network license” sign, and a bar code. Our maintenance staff, in addition to the simple recognition, but also with other recognition.
First of all, to tell the phone case. Assembled machine in order to save money, often not using the original chassis. In case the black color on the original machine is dark black, not reflective; rather than the original shell is black though, but the smooth surface will be reflective, the black is a black, not polished grainy. If the color of the case, the original shell is also not reflective, there is a polished grainy, deep colors have intensity; rather than the original chassis smooth, reflective, making the color too bright glare, appears to grade is not high enough. Shell color that is often difficult to distinguish between mobile phones, but as long as we compare the color change and transition, is also able to separate the. General original color shell from a different angle, looking at the light will show different colors, and the particles are polished management. And appears thick, and the color change of natural harmony; non-original case is showing no depth is too bright, color dull. But now many of assembling machine in order to deceive customers, often buy original case packaging, so we have to check the next step.
After identifying label case is very important. In addition to licensing the shell after the network card industry, there is a cell phone before leaving the factory each product must be affixed to prove. In the back paste this, marked with the following items:
① IMEI number, the mobile phone device identification code is formed by the 15 digit number.
The IMEI number of each phone is definitely not the same, it represents the identity of a cell phone, curing the chip in the machine on board is not free replacement. In some countries mobile communication system, in order to protect the legitimate interests of users, the system will drive a digital phone number and IMEI number checked simultaneously. Say, if your phone was stolen a number, he used his mobile phone SIM card coupled with your use of the system is not recognized, that he is not available. And you only need to fix your behalf on a number of the SIM card on it. This will protect the legitimate interests of users. Of course, if you have both lost your cell phone and SIM card, which requires the department to apply for business downtime or re-purchase a SIM card, business, and you also need to buy a digital mobile phone.
Examination IMEI number and mobile phone shell read the IMEI number is the same, is the most direct way to determine whether the phone an important tool for the assembly machine. IMEI read in the machine is simple: Replace the battery, boot, turn on the keyboard typing * # 06 #, you will see on the screen body this phone number (ie IMEI number). But M0TOR0LA’s 8200,7200 and other early products, in this way can not see the IMEI number, need special testing card (TEST CARD). Use as follows: the same as the installed SIM card into the test card from Jianpanshangqiao into the # key, enter the test state, knocking on people * # 06 #, read the IMEI number, and the back cover quote on the IMEI number back comparison. IMEI number, but not to say that certainly is not the same assembly machine