iPhone 7 phone water plug no 4G signal failure

Faulty model】:iPhone 7

Fault phenomenon: No 4G letter on water inserted card

The phone is in the water, the plug-in card has a 2G signal, no 4G signal.

[Failure Analysis].
The phone can be on 2G signal, not on 4G signal, indicating that the 4G signal part of the problem, the phone is water before this fault, then water parts in the 4G signal channel caused by.

[Repair process].

Mobile phone disassembled, take off the motherboard, microscope observation, observation is not out, remove the 4G amplifier chip.

Remove the TDDPA_RF 4G amplifier chip, measure the ground resistance of the pad, found that the 11 pin MLB_PA_VBATT to ground infinity, it seems to break the line.

View the circuit diagram, found that this voltage to TDDPA_RF, MLBPA_RF 2 chip, MLBPA_RF this chip is not installed.

This voltage is PP_PA_VBATT through R7113_RF resistor renamed MLB_PA_VBATT, microscope observation, found that R7113_RF resistor has been corroded.

Check the circuit diagram labeled as 0 ohm resistor, directly shorted it.

Put the chip back on, install the machine test.

[repair results].
Test 4G signal back to normal, water caused by 4G amplifier power supply is insufficient, caused by no 4G signal, to the end of this repair.

iPhone 6 Plus phone reboots automatically from time to time

Faulty model: iPhone 6 Plus

Fault description: automatic restart from time to time

Repair process.

According to the customer’s description, the machine is faulty for irregular automatic restart. Connected to the ammeter charging, found that the current is 0.05A, basically no current, is not charging.

At first, I thought it was USB and charge management chip problem, first disassemble the motherboard, and connect the USB management chip and charge management chip around. The capacitors, resistors hit the ground value, and found that the ground value are normal. Then measure the tail plug whether there is a 5V power supply output, 5V power supply is also normal.

Customers since the restoration of factory settings, the first brush in the boot test, boot, prompt does not support this accessory, and let me boot suspected Is not USB bad, test and online video and other functions are normal, no reboot. Pick up the machine first to open the screen a split second, suddenly reboot, is the battery holder contact bad? Quickly look under the microscope, scrape a bit of the test foot copper with a pair of tweezers, then load the battery and turn it on.

After an afternoon test, no reboot phenomenon found again, the fault is perfectly eliminated.

iPhone 6 phone screen half bright and half dark

【Model】iPhone 6

Fault phenomenon] The phone screen is half light and half dark, yin and yang screen
[Repair Process]
Customer an Apple 6, the fault description says it is not on. With an adjustable power supply, power on 30-60-100-120, the current is normal, careful observation of the motherboard, should not be repaired. Measure to show seat J2019, measure each foot to ground value, 26th foot 0l, infinity, and check further down. fl2037 broken wire, measuring resistance, the tip of the nib touched and fell off, the original is this inductor virtual solder, immediately re-soldered. XinZhiZuo software in the iPhone 6 point map, as follows.

And then power on the test, yin and yang screen.

Yin and Yang screen many are backlight circuit caused by burned-out backlight circuit components, generally as long as the circuit in the burned-out components for a solution.
Play display seat resistance, found 2 feet backlight circuit 1 broken line, will FL2025 inductor short, resistance value is normal.

Hit the display seat resistance value again, all normal, power on the machine test.

Start-up screen display is normal, test all kinds of normal functions, maintenance to this end.

iPhone 6p phone external no sound, headphones normal

Faulty model] iPhone 6p 64g

[Fault phenomenon]

Customer description said the phone external sound, insert headset normal, vibration and answer the phone are normal.

[Failure Analysis]

The boot test is indeed the same fault as described by the customer, because plugging in the headset normally represents the working condition of the phone big audio is already met. It could be a problem with the big audio chip and the audio amplifier or the I2S2 (the audio cable for the external amplifier). It could also be caused by the external pairing.

[Repair Process]

First troubleshoot the external match problem, the phone motherboard removed into our test machine rear shell assembly inside, boot test again found that the original fault. Now you can basically rule out the reasons for external distribution, the target directly aimed at the large audio IC disassembly chip, observe the pad with or without tin and drop point. All normal directly to the material board to remove a large audio IC tin mounted. And then this boot test found that the fault is still the same, now basically rule out the cause of the big audio IC. Disassemble the audio amplifier, measure the corresponding points, found 45_AP_TO_CODEC_XSP_I2S2_, and then remove the audio amplifier. BCLK (I2S2’s clock signal) is disconnected.

This point is only connected to the big audio, audio amplifier and CPU, dismantle the big audio to measure the corresponding point found resistance value is normal, directly from the big audio below to pull a first fly line to the audio amplifier to the corresponding point.

Directly mount the audio amplifier, power on the test.

Repair results]

Power on test, normal external playback, fault repair completed.

iPhone 6s Phone Moves Board Causes CPU Drop Point Repair

Model: iPhone 6s

Fault phenomenon: The CPU on the moving plate drops a little bit.

Moved the board, removed the CPU and found a spot dropped on top of the CPU.

[Repair process].

Look at the point map, the dropped point is on the I2C0_AP_SDA bus, scrape the over-hole point next to it on the microscope, tin it, find a line to scrape as thin as possible, blow the wind gun to blow the fly line on the tin, cure the green oil.

Plant tin.

Solder the lower layer, power on normal.

Install the upper layer, move the hard drive, baseband, code piece, brush through normally, move the board over!

Huawei mobile phone standby time is too short

Solution: For the old mobile phone, the first thing to think about is because of battery aging this situation, you can replace the phone battery way to solve the problem, suggested to the repair place first check the specific situation, many mobile phones are now non-removable battery, or need professional maintenance personnel to solve the replacement problem, and do a good job of mobile phone backup Oh.

For the new mobile phone, you need to do the following: 1, in the use of wifi, Bluetooth, gps or data services, the corresponding functions will be turned off;