第七章：手机自动开机、低电告警、充电与漏电故障维修第七章手机自动关机、低电告警、充

第七章：手机自动开机、低电告警、充电与漏电故障维修第七章手机自动关机、低电告警、充 第七章:手机自动开机、低电告警、充电与漏电故障维修第七章手机 自动关机、低电告警、充 Maintenance foundation - Chapter seventh: mobile phone automatic start, low power alarm, charging and leakage fault maintenance, the seventh chapter, mobile phone automatic shutdown, low power alarm, charging and leakage fault maintenance Mobile phone repair process, charge, low voltage alarm, automatic shutdown, shutdown and leakage can not occupy a certain proportion, because a considerable part of the maintenance personnel do not pay enough attention to this part of the contents, not deep understanding, resulting in the maintenance is difficult. In order to facilitate the maintenance of readers, this chapter systematically analyzes the maintenance methods and troubleshooting skills of such failures. Section 1 maintenance of abnormal charging Although all kinds of mobile phone charging circuit is different, but the working principle is basically the same, that is, charging circuit generally has three parts of the circuit. Is a charge detection circuit to detect whether the charger is inserted into the mobile phone charger; two is the charging control circuit is used to control the external power supply to the mobile phone battery charge; three is the detection circuit of the battery, how to detect the rechargeable battery, when the battery is full to the logic circuit provides a "charge" so, the signal, a logic circuit for controlling charging circuit disconnect, stop charging. In general, when problems arise when the charge detection circuit, there will be start charging, charging display symbols such as fault, when problems arise when the charging control circuit, the general will not charge fault; when a fault occurs when the battery power detection circuit, usually occurs when charging or charging always shows charging symbols but not charge fault the. First, Motorola mobile phone charging circuit analysis and maintenance Motorola V998 mobile phone charger connected through mobile phone and mobile phone J600 interface tailstocks, J600 5 feet (MAN-TEST) for charging type detection terminal, is used to detect the charger charger or speed charger, J600 8 feet (EXTCHG-EN) is used to detect end of charge detection, the charger is inserted into the mobile phone charger, mobile phone is charging J600, 14 feet for the external power supply to the D10 end of the EXT-B+, U900, and R932 through the sampling resistor (0.25 Ohm) to the charging tube Q932 4 foot and U900 U900 D9 (1SENSE) port. U900 according to the magnitude of the R932 resistance, the charging current on the R932 can be calculated. After comparing the current with the standard current, the charging control signal is output to control the turn-on degree of the Q932 and further control the magnitude of the charging current. When the U900 terminal F7 (battery voltage BATT+) detected battery voltage is not saturated, and the mobile phone with the external power supply, CPU charging control U900 control terminal ElCHRGC outputs a low level control, Q932 start charging circuit, an external power supply by R932, Q932 and CR932 to charge the battery. When the U900 port of the F7 detects that the battery voltage is high enough, the charging control terminal CHRGC outputs a high level, closes the Q932, and the external power supply stops charging the mobile phone. However, the external power supply continues to provide power to the mobile phone until the phone is disconnected from the external power supply. As can be seen above, when the U900, CPU, Q932, and the external power supply [3J600 bad, will cause the mobile phone can not charge or charge abnormal fault. Two 、 NOKIA mobile phone charging circuit analysis and maintenance Take NOKIA 3310 mobile phone as an example. 3310, the mobile phone charging circuit is mainly composed of charging control module N200, power module N201 and central processing unit D300. When the charging power supply into the mobile phone, charging voltage directly to the charging control module N200 and A2 feet, N201 detects the charging voltage of power supply module has give mobile phone, it immediately put this signal to the central processor D300, and then D300 sends control signals to the power module N201, make it from B5 feet (PWM) pulse to send 1Hz the charging control module of N200 F2 feet, let the internal charging switch is closed, the charging voltage from C6, D6 feet sent to charge the battery. When the PWM signal is high level, N200 internal SWITCH (charging switch) closed, charging the battery, when the PWM signal is low, SWITCH is in a state of separation, N200 will stop charging the battery. In the charging process, the power module N201 monitors the voltage difference across the resistor R204 to determine whether the battery is fully charged. When the battery has been fully charged N201 judgment, it will send the signal to the central processor D300, and then D300 sends control signals to the power module N201, to stop sending the PWM charging signal, so that the charge control SWITCH separation module N200, stop charging the battery. If the charge voltage is too high, it can be dangerous to the cell phone. Nokia 3310 type mobile phone is provided with a protective circuit. After the mobile phone is switched on or in the charging state, the central processing unit D300 sends out the charging voltage limiting control signal (CHAR - LM) to the F4 foot of the charging control module N200. This signal is used to detect the charging voltage is too high, when the charging voltage is too high, will take this signal to low level, the central processor D300 detected, immediately send an interrupt signal through the V205 switch to N200 switch in the charge separation, stop charging the battery. As can be seen from the above, NOKIA 3310 mobile phone charging circuit better protection measures, the circuit is a bit complicated. The following example analysis of charging fault repair. Three, Samsung mobile phone charging circuit analysis and maintenance The following example of Samsung A188, A288 mobile phone for analysis. A188 mobile phone standby charging circuit is composed of charging control module U605, U609, U607 and CPUU201, the charging power supply by the external charger provided from CN601 (V-EXIT) by L608 to the inductance L607, charging module of U605 14, 15 feet. The U605, together with the peripheral elements of 2, 3, and 7 pins, form a switching oscillation circuit which provides a charging mode of the PWM to the charging circuit. When CN601 receives the external power supply, external power supply through a resistor R643 to U609 5 feet, at this time, U609 3, 4 feet will be conducted, the external power supply to the power detection signal TA-DET module U401, at the same time, the external power supply through a resistor R643 to U607 5 feet, 3 feet of the U607 control signal TA-PRENT decreased, and the signal to the central processor U201 Ell pin. The U201 detects the change voltage and starts charging function through the bus. Output charging control signal from U201's A4 pin. The charging control signal is controlled by 6 feet of the U609, and the twelfth foot of the U605 starts the U605 operation, U605 outputs the charging power from the 10 pin and charges the mobile phone battery via the diode D609. R637 and R639 constitute a partial pressure detection circuit, added to the multi-mode ICUl01 B9 pin (BP-DET), the detection circuit to detect whether the battery is full, When the detected battery saturation, multimode IC-Ul01 notification logic circuit of battery saturation, CPUU201 control off the charging circuit through the CHARGER-DISABLE signal at the same time, the battery is full state display screen mobile phone. Relative to the A188 mobile phone, A288 mobile phone charging circuit is much simpler, charging circuit is composed of Q303, U639 and other components, the charging voltage DCVOLT from the CN502 external interface seat seventeenth, eighteenth pin input, when the charging seat inserted after the mobile phone DCVOLT, the voltage signal through the base of the R157 and R161 sampling Ulll then, the collector RTC-3V3 is installed on the battery, so the Ulll emitter can output a high level signal to the microprocessor DCIN U108, used to detect mobile phone charging control circuit state. When the U108 detects that the charging seat is inserted after the mobile phone DCVOLT, charging voltage by U639 amplification from the 6 sampling, output voltage control of U639, the Q303 control from the anode collector output to the battery, whether to stop charging, controlled by the U639 fourth foot pulse (CHG-ON) decision, CHG-ON pulse from the micro processing U108. R320, R671 pressure after the battery voltage, as the degree of saturation of detection signal is sent to U108 for detection, when the detected battery is not saturated, CPU output CHG-ON signal, DCVOLT control of mobile phone battery, when the check that the battery is saturated, CPU output CHG-ON signal, DCVOLT continued to cut off the battery charging. Second section automatic shutdown fault repair Mobile phone and automatic shutdown, automatic power-off, and divided into regular shutdown, shutdown button, call shutdown, boot after shutdown, can not maintain the boot, shutdown shutdown and close the flip emission seven, the fault is more annoying and difficult to rule out the fault repair, are often unable to start, even some maintenance experience the "master" also feel at a loss, in fact, as long as the maintenance notice, to seize the essence of fault, this fault repair is not difficult. The following are analyzed separately. Automatic shutdown Mobile phone does not stop regularly, refers to the phone boot, access, call is normal, but sometimes suddenly shut down. This fault mainly has two kinds, one is due to contact between the battery and the battery caused by poor contact; two is the voltage output of the power supply IC instability, power supply circuit of the weld or poor contact caused by mobile phone protection. Mobile phones caused by dampness and falling on the ground are liable to cause this phenomenon. Inspection should first check whether the contact of the battery contact well, if normal, we should focus on strengthening the circuit welding. Two, button shutdown As long as the mobile phone keys, will not shut down, according to a certain key mobile phone will automatically shut down, the main reason is the key element in integrated circuit or weld, when the key is due to the role of the weld site lead desoldering, mobile phone shutdown. Maintenance time, As long as targeted to strengthen the lower part of the button integrated circuit or component welding, can generally solve the problem. Three, call off Call off, that is, the phone can boot, access, but also to make calls, but when the phone rings, calls, the phone will turn off. This kind of fault seems complicated, but in fact it is very simple. Why does the telephone call turn off? It is only caused by ringing. Why does the phone turn off when ringing? This is because a lot of ringing work is powered directly by the battery voltage BATT+. When the ring is broken, it will cause the call to be switched off. Four, turn off the power Mobile phone shutdown after shutdown, there are generally three reasons: First, the mobile phone power supply circuit failure, so that although the mobile phone "barely" to meet the conditions of the boot, but the boot will be switched off after a while. Especially with the booster circuit of mobile phones (such as Motorola, V998, Samsung, A188, 600 mobile phones, etc.) more prone to this fault. We know that the mobile phone battery voltage is very low, generally about 3.6V, some mobile phone battery voltage is lower, such as battery powered mobile phone NOKIA 3210 2.7V only, but a lot of the mobile phone circuit voltage, require a higher so that some mobile phone set a boost circuit. When the boost circuit fails and the boost circuit has an impact on the switch machine of the mobile phone, it is possible to cause the handset to turn off automatically after the switch is turned on. Two is the mobile phone power supply load circuit, in the malfunction, causes the handset to consume the electricity to be big, will supply the electric circuit voltage to pull low, causes the handset to protect to shut down. In particular, the launch circuit of mobile phones is most likely to cause excessive load on mobile phones, causing the phone to turn off after the boot. For the transmission circuit caused by the shutdown after the failure, the general overhaul of the way is: SIM card will be removed, boot, if there is no automatic shutdown phenomenon, indicating that the automatic shutdown fault occurred in the transmission circuit. Because in the case of placing SIM cards, the cell phone searches the operating network and automatically sends user signals to establish communications with the network. With the SIM card removed, the phone searches only for the public network, but does not determine which is the operating network, so it does not automatically open the transmitter. Three is software failure. When the software is not normal, the mobile phone may also turn off after the boot. Automatic shutdown after boot, there are some other reasons, maintenance should be based on the phenomenon of specific analysis. Five, can not maintain the boot Can not maintain the boot, press and hold the power refers to the key to boot, but release after automatic shutdown, the fault is more common in Ericsson mobile phone, especially T10 T18, Ericsson mobile phone probability appears more judgment method is: If you continue to press and hold the boot button after starting the phone, the phone is switched on, and you can register on the Internet. When you loose the key, the phone will turn off automatically. This phenomenon is generally maintained on fault signal caused by abnormal, we know that the software and hardware self-test only through CPU, to produce the boot maintain signal, can not produce boot sustain signal continuously, one is part of CPU damage caused by two, software is not normal. If you press the boot button, after the boot, continue to press and hold the boot button, the phone can boot, but can not register on the Internet, but automatically shut down and then boot, and then automatically shut down and boot...... , Repeat the shutdown and then boot phenomenon. One reason is the weld or damaged components, such as font, CPU converter, multimode bad welding or damage etc.. The two is the software error, change the font, or piece of code to overwrite the data. Six, close the flip off Clamshell and folding mobile phone is sometimes a very strange fault, namely flip open call normal, but on the flip mobile phone shutdown. But open the cover and then boot and boot, and then close the flip and then shut down...... We know that mobile phone flip with automatic answering the phone and automatically shut off the phone function. The main components to complete this function is that the magnetron, clamshell and folding mobile phone commonly used reed or Hawke element, clamshell and folding mobile phone with the early dry reed pipe, now new clamshell and folding mobile phone is the use of Hawke element. However, the control principle is the same. The mobile phone cover, a small magnet flip away from the magnetron, external magnetic field disappeared, automatically disconnect the internal circuit of magnetron, the "off" signal (usually a high level) are sent to CPU, CPU as signal and answer the phone (or open background light); when answering the phone. When you close the flip, flip the small magnets near the magnetron, due to the magnetic field, the magnetron internal circuit is switched on, the signal "on" (usually low) are sent to CPU, CPU as hook signal and shutdown (phone or turn off the background light). The 600 Samsung mobile phone flip circuit adopts dry reed pipe, dry reed pipe shell is a sealed glass tube, the elastic reed electrode two is arranged in the iron in the glass tube, glass tube filled with an inert gas. The usual two reeds in the glass tube is separated, when on the flip, the small magnet flip near the glass tube, in the magnetic field, the two reed pipe is magnetized and attracted to each other, so that the circuit two pins connected connected to CPU's 50 foot. CPU, get a low level signal, the mobile phone off the phone (or turn off the background light). Open the cover, the external magnetic field disappeared, two of the dry reed pipe by its elastic and separated line is disconnected, the CPU 50 feet because of the pull resistance R340 effect and rise to a high level, so the CPU command on the phone (mobile phone or open background light). Can be seen from the above, the 600 Samsung mobile phone on the flip off fault, said CPU is actually 50 feet as long as the low level signal to shut down. The cause of this failure is mainly caused by local damage, CPU. The solution is to replace the CPU or CPU implants. Emergency repair method is to remove the dry reed pipe or small magnets on the flip, the CPU is always 50 feet high, but doing so will make the mobile phone out of the opening and closing of the automatic shutdown and automatic answering flip phone function. Clamshell Samsung A188 mobile phone circuit uses a Hawke element, when the flip is closed, the cover in the magnetic field in the Hawke U2 Hall sensor, a sensor circuit inside the tube, first feet from the sensor output low level. If in the call, as signal to the microprocessor on hook hook. When the lid is opened, The hall sensor is not affected by the magnetic field, and the diode in the Hawke sensor circuit is cut off. The output level of the 1 pin is high, and the change of the pulse voltage (FLIP-SNS) is added to the D5 pin of the CPU-U201 on the motherboard. So CPU orders the phone to turn on the phone or turn on the background light. For other flip or folding mobile phones, such as Samsung, A288, Ericsson, T28, Motorola V series mobile phones, etc., if the above fault, but also in accordance with the above methods for analysis and maintenance. Seven 、 transmit off The launch and shutdown faults of mobile phones often occur during the maintenance process, and the reasons are mainly from the following aspects. One is the battery voltage is too low or battery aging. For battery voltage is too low to cause the phenomenon of emission shutdown, as long as the replacement of sufficient batteries, power supply normal, you can determine the mining. There is a relatively easy to misjudge the fault is due to battery aging caused by emission shutdown, often encountered battery shows still full, but fired off, this phenomenon is mainly caused by the aging of the battery after the battery internal resistance becomes large, when transmitting current, the output voltage of the battery is low emission caused by the shutdown. Two is the output of power amplifier after no-load, to protect the power amplifier burned and shut down. The amplifier output has damaged element or weld phenomenon will cause the amplifier output load. Three is software failure, resulting in mobile phone shutdown. Four is the power control circuit is not normal, causing the launch shutdown. After the launch shutdown failure, should find the reasons from the above aspects, of which the power amplifier part of the failure caused by the most common. Third low voltage alarm fault repair 1 、 low level alarm analysis Low voltage alarm fault refers to the normal battery board, low battery or power grid is still not full display display, following with Motorola V998 mobile phone as an example, analysis of the causes of low voltage alarm. The low level detection principle is: battery voltage BATT+ to ICU900 power supply F7 foot pressure for the sampling in the interior, and then A / D conversion, the battery voltage of the data signal converted to communicate through SPI-DR, SPI-DW, SPI-CLK, SPI-CE serial bus and CPUU700, and the normal data and FLASHU701 in comparison the battery voltage information, and through the display circuit are displayed on the screen. When the CPU is informed that the battery is low, the low voltage alarm signal is sent out. When the battery power is normal, the CPU still sends a low voltage alarm signal, which shows that the mobile phone is out of order. Two, low voltage alarm reason The main reason for the low voltage alarm fault of Motorola V998 mobile phone is mainly as follows: 1. the battery contacts black Clean the contact with small file or sand paper. Sometimes, the battery is bad, there will be a phone call or battery use for a long time, that is, a low power alarm failure. 2. power IC bad V998 mobile phone voltage detection by the power ICU900 internal voltage division, A / D (analog / digital) conversion, and the data sent to CPU, and memory in the normal data for comparison. Such as the power IC, the internal MD converter is not normal, It will cause low power alarm. 3. software chaos If the software set low alarm threshold voltage is too high, it will produce a low voltage alarm fault. During maintenance, only the correct data can be rewritten. 4. battery power supply load circuit leakage If the battery power supply load circuit such as amplifier, large leakage current, will pull low battery voltage, resulting in low power alarm. The main characteristic of the power amplifier circuit is damaged by the launch button large current. This and other reasons is the difference. The fourth section mobile phone repair leakage fault A mobile phone, the leakage fault maintenance method Leakage refers to the mobile phone mobile phone with DC power supply, according to the current table pointer button on a current instruction or mobile phone boot standby current. Under normal circumstances, the mobile phone does not boot ammeter indication value should be OmA, the standby current is 5~30mA, the maximum should not exceed 50mA. Some mobile phone users, mobile phone batteries own fast consumption, the full power of the battery is not how long the low power alarm or automatic shutdown, this kind of failure is usually caused by leakage of mobile phone. The mobile phone will not cause serious leakage of boot failure. Causes of leakage fault is generally bad or a power supply integrated block element with short-circuit phenomenon, into the water mobile phone prone to leakage fault, leakage fault maintenance is difficult, maintenance, can use the following three methods of analysis and judgment. 1. temperature sensing method To supply mobile phone a few minutes, and then touch the suspicious element, the heating element is not normal fault. This method is suitable for the leakage current is not a lot of mobile phone repair. 2 experience Directly after a fault can be ruled out to replace power. This method is suitable for mobile phone repair large leakage fault. If the mobile phone is a large leakage current, mobile phone plus short circuited or current regulated power supply is rising rapidly, according to the experience of the general cause for power amplifier circuit, power amplifier can be directly replaced after fault exclusion. This method is suitable for mobile phone repair large leakage fault. 3. disconnect method If using the above two methods still can not rule out the fault, the fault leakage mobile phone is hidden, according to the experience of the leakage fault generally occurs in the part of the mobile phone battery direct power supply circuit. These parts are mainly: battery and filter circuit, power IC, power amplifier circuit, oscillator circuit, ringing circuit, battery backup circuit, electronic switch (different mobile phone battery direct power supply circuit, may not be the same). Repair method can be adopted to judge one by one off. [this post has been edited by 2004-12-11 author 19:36:18] Metaprotein - At there is a fate in a hurry having having having will Having a waiting at the current stage of having having enduring as the universe At having having a feeling looking forward to continue having the current stage A good heart will never hide at having a handsome monkey L 2004-4-22 0:57:00 report posts