What if the phone doesn't work
While it is believed that most people have experienced the failure of mobile phones, which may have different reasons for both smart and non-smart machines, in general there are the following situations, which generally can be resolved by checking the situation below。
I. Non-opening caused by abnormal opening lines
In normal circumstances, when pressing the opening key, the trigger end voltage of the opening key shall change significantly, and if there is no change, the opening key shall generally be poorly exposed or the opening wire shall be cut off, the component welded, damaged. During maintenance, electricity is supplied from external sources to observe changes in current meters, which, if not responded to, are generally open-wire breaks or bad opening keys。
Ii. Non-opening caused by poor power supply circuits
For most mobile phones, the power voltage is added directly to the power supply c after the cell phone is added to the battery or external power supply, and the mobile phone cannot be turned on if the power is not added to the power source ic. For mobile phones in the motorola series (except for motorola t2688), electricity is different, and battery power and external power supply are converted via electronic switches and added to the power source ic. In other words, there are two paths to mobile phone power, one by battery, and the other by external interface (when power is provided with a charger). When both power lines are simultaneously powered, the external interface gives priority to the power supply. The switch between these two circuits is controlled by an electronic switch, mainly to protect the entire electrical current from damage caused by short circuits or leaks to integrated circuits inside the mobile phone. However, if the electronic switch is damaged, there is a risk that the medium source module will not have access to battery power voltage, causing the mobile phone to remain on. For such mobile phones, which are powered by electronic switches, it can be powered either by an external power interface or by an external power source from a battery contact. The power can be supplied by different means of supply to distinguish the failure range and determine whether the electronic switch is normal. In general, if the power supply is poor, the button-button current table will not react, which is very similar to the failure of the open line。
Iii. Resources of ic arrangements
Cell phones work normally and power circuits export normal voltage supply load circuits. In power circuits, ic is its core circuit, with different types and models of mobile phones and different modes of supply, some of which are supplied by several steady-pressure tubes, such as ericsson's earlier series (before t18) and some of the three-star series. In some cases there is a direct supply of power modules, such as motorola, nokia, etc. But in any case, if the power supply is not working, there is a risk that the mobile phone will not be turned on. For the power source ic, the emphasis is on checking the logical power voltage of its output, the power voltage of the 13 mhz clock, which should be detected (and not necessarily maintained) during the process of pressing the switch button, and, if not, the fracturing and damage of the power source ic in the event of a normal battery supply. Currently, an increasing number of power sources have adopted bga seals, placing a heavy burden on measurement and maintenance, which can be tested at the test point of the external circuit of the power source ic against the chart of the principle of the circuit. If the power source ic is judged to be welded or damaged, it needs to be replanted and replaced with tin, which requires high operational skills and needs to be refined in practice。
Iv. Non-opening of systems due to irregular clocks and resets
The system clock is one of the conditions for the normal operation of cpu, and the system clocks for mobile phones usually use 13 mhz, 13 mhz hours are abnormal, logic circuits are not working and mobile phones cannot be turned on. The 13 mhz clock signal should reach a certain range and be stable. The wave shape of the output end of the 13 mhz clock is measured with a oscillator, and the power voltage of the 13mhz clock oscillating circuit is detected if it is not wave-shaped (for 13 mhzvco, the power voltage is added to one foot of 13 mhzvco, and for 13 mhz crystal vibrating circuits, which is generally the medium frequency of the ic for the supply), when the normal voltage is not. Note that some oscilloscopes are measured on crystals that may cause the crystals to fail, at which point a tens of skin cap may be attached to the head. Depending on the conditions, it would be preferable to use replacement methods for maintenance in order to save time and increase efficiency. 13mhz-hour circuits shall be activated by ensuring that the 13mhz-hour signal is passed to the cpu-led foot by electrical resistance, conceiving and magnifying circuits, testing the cpu-hour entry foot and, if not, checking whether the circuits are welded or without electricity and damage. In addition, some mobile phones have a clock crystal or a clock vco that is 26 mhz (e. G. Motorola v998, noki 3310) or 19. 5 mhz (e. G. Samsung a188), and the resulting oscillation frequency is supplied to cpu only after the medium-frequency ic split to 13 mhz. The duplicate signal is also one of the cpu's working conditions, with the symbol reset, abbreviated by rst, which is represented by purx in the nokiaan machine. Relocation is generally directly from the power source ic to cpu, or using a special-purpose sub-integrated circuit. The reset is in place at the moment when the engine is on, and it is measured at high level. If it is necessary to measure the correct double-time waveform, double-trace wavelengthers should be used to measure cpu power along the way and repeat position along the way. Maintenance found that mobile phones were not available due to irregular re-routing。
V. Non-opening due to irregular logical circuits
Logical circuits focus on testing cpus for selected ces and licensed oes for storage units, which are important, but the key is that these signals must be found, and the increasing use of bga-enclosed integrated circuits on mobile phone logic circuits poses considerable difficulties in finding them. Depending on the conditions, it is best to look for these signals and their measurement points against the drawings. The selected signal is some of the pulsed up and down, indicating that the cpu is not working, welding, welding, replacing, or then carefully checking whether cpu conditions are in place. If the selected signal of a memory does not exist, it is mostly damaged. If both ce signals indicate that cpu-f. Is normal, the failure may be a software failure or a bus failure and damage to a storage unit. Cell phones are often used to deform the panels, and external forces such as buttons, falls, and bumps cause the welding of certain chips, which are usually welded or welded to solve most of the problems. When welding or replacement of normal chips is not operational and reading and writing cannot be performed using a derelict maintenance machine, each outer circuit and replacement of the chips should be measured。
Vi. Non-opening due to irregularities in software
Cell phones can be opened if the software is unserviceable, and errors in the software are due mainly to abnormal memory information, which can be replaced by normal code, version or rewrite software when the line is not significantly disconnected, and some internal circuits within the chip are damaged and cannot be rewrited. When rewriting the software, the original information should be kept for emergency repairs。
Vii. Other reasons for not operating
There are many reasons for the failure of mobile phones, such as poor liquid crystal display screens, short circuits of components (especially work placements), which may cause mobile phones not to turn on, and some types of real-time clocks that have to be used to signal code clocks and sleep clocks. If the real-time clock is abnormal, 32,768 khz may also cause the mobile phone to remain on. The factors contributing to the irregularity of the clock at 32. 768 khz are, inter alia, short circuits for the backup battery of the clock, 32. 768 khz, etc. Therefore, when a mobile phone is not open, it should be analysed in conjunction with specific circuits, and failure is generally ruled out as long as it is correctly understood and thought clearly。
Methods and steps:
Step 1: check if the battery is powered, the battery is powered, the mobile phone naturally has no power to turn it on, and check if the charger is not working, if the interface is damaged, and if the battery is charged or measured with all power。
Step 2: check if the battery is damaged or has reached its lifetime and the battery is a consumer. If it is damaged or inappropriately used to cause premature damage to the battery, an attempt can be made to replace the battery to see if it can be activated, and if the problem is resolved, the battery will need to be replaced。
Step three: cell phones fail for long-use, low-quality masonry machines, most prone to damage, causing problems inside the mobile phones to fail to turn on, so you can search the situation online, ask for help from your friends, or you can find a solution for sale during warranty。
Step four: the problem of human damage caused by water intake or brushing machines is one of its own causes, with a blowtorch and a debunker to bake for a test, which, if broken and internal parts destroyed, would require repair at the maintenance centre. If the brush is unable to turn it on, the brush can be restarted。
Step five: if the basic methods have been tried or are not working, then you have to go to a professional maintenance centre to do the maintenance, which usually can't turn on the failure itself, or try to find a solution that suits you。
This post is part of our special coverage of the world summit on the information society. In fact, it is easy to deal with this when it comes to finding out what causes it. If a professional maintenance centre is needed, the editor reminds the major internet users of the need to find a formal brand maintenance centre, which can be found in the network of brand officials, so that they do not go to unlicensed or under-trusted shops in order to save money, otherwise the mobile phone will end up being badly repaired, and the money will be lost。
