iPhone 6 Plus fingerprint function not working repair guide

Fault phenomenon

The customer has repaired the WiFi fault and camera circuit, the camera 2.85V Camera FlashControl IC U2301 has been replaced, the fingerprint cannot be entered, as shown in picture 4-7-1.

Repair process

According to the customer's description, Camera Flash Control IC U2301 has been repaired, because the position of U2301 and fingerprint power supply IC U2100 is close next to each other. After the check, we found that U2100 is slightly damaged, so we are determined to remove one from the motherboard, soldering Tin ball and reinstall to failure board, then boot and test it, but the fault is still the same. Next, we start to measure the output pin A2 pin of power supply conversion IC U2100 with multimeter, see if it has 1.8V voltage output, find the peripheral capacitance C2181 and test it; we found that it could measure to 1.8V.

The picture of the fingerprint power conversion chip U2100 replacement is as follows, 4-7-2

Based on the above measurements, the power supply is normal, which means the U2100 circuit is installed. According to the principle, now we only can measure the diode data of J2118 pin on the motherboard first, after measurement, we found that the diode data of sixth pin on J2118 is infinity, which shows there is a disconnect between this line and fingerprint boost chip. Check it in the schematic diagram, we know that there is a inductance from sixth pin of J2118 to fingerprint boost IC U1503, we can found the diode data on first pin of inductance.

The conclusion is that the inductance FL2156 is inveracious soldering or damaged. Put it under the microscope, and remove the black glue around the FL2156, paint the UV solder flux and then solder it with soldering station, as shown in picture 4-7-3. Once again to measure the diode data of sixth pin on J2118 adapter, the data is no longer infinitely large. Turn on iPhone and test it, the fingerprint can be entered normally, as shown in picture 4-7-4.

iPhone 6 Plus battery percentage issues? Here’s excellent solution!

Why the battery power percentage is incorrect?  It will affect our use of iPhone. What's worse?  It reboots frequently. We need to investigate the cause of the faulty and find the excellent solution.

First test the charging function, it shows normal, but the battery power percentage jump frequently. Base on repair experience, this phenomenon should be a reboot frequently caused by battery failure, so we should repair the battery power percentage inaccurate first.

Connect iPhone to i4 tool, the position of battery information shows no data, this failure is the CPU doesn't recognize the battery, so i4 tool can't read the battery data. As shown in picture 4-5-1.

 

The main reasons for not recognizing battery information as follows:

1. The battery is damaged

2. The circuit from middle pin BATTERY-SWI of battery interface J2523 to F2 of charging chip U1401 is broken and the U1401 was damaged

3. The problem of circuit from U1401 G1 # to CPU AG4 # and problem with the CPU itself.

The schematic diagram is shown in picture 4-5-2

Replace the new battery and test it, i4 tool still can't read the battery information. Then measure the diode data of battery middle pin with Multimeter, the diode data is 380 which is normal, so the line from battery to U1401 is normal. Next we remove the U1401 IC, and then measure the line from G1 pin to SWI of CPU, the diode data of G1 is 450, its normal. Now, we can judge U1401 or CPU is damaged.

After replace the U1401, it still can't read the battery. This fault is not caused by the CPU welding, but because the CPU damage pulls down the voltage of the SWI line, so we can increase the SWI voltage by connecting the resistor externally.

Connect a 2.2K resistor on PP3V0_TRISTAT, the other end of the resistor is attached to U1401 G1 pin (also can connect to middle pin of battery). The picture of solder jump wire is shown in 4-5-4.

After soldering jump wire, the picture is shown in 4-5-5

Finally, turn on iPhone 6 Plus and connect to i4 tool, now it can read the battery information, the fault has been repaired. As shown in picture 4-5-6.

Tips: you can use 3U tool to replace the i4 tool.

Repair guide for iPhone 6 motherboard dropped many pins

Recently, we got a iPhone 6 from our customer, this iPhone 6 has some problem, it burned out when it was charging, and it's been repaired, but it turned out to be a failure. We preliminary judgment is USB management chip drop pins,  as shown in picture 6-81.

For those motherboard  whose pins drops seriously, I have to replace it with other workable motherboard. That is to say, remove all the major parts to other workable motherboard. Find a iPhone 6 motherboard in picture 6-82.

Remove all the chips and tin them. First solder main power supply, USB charge management chip, charge field tube, NAND Flash and CPU and so on, as shown in picture 6-83.

Then turn it on and it can display normally, as shown in picture 6-84. The previous parts are soldered normally. Next I continue to remove the small parts.

After removing all the parts. Turn it on and get into IOS to test. All the functions are normal. “about iPhone” can display all the serial number, as shown in picture 6-85.

SHARE: summary of methods for repair iPhone touch problems

 The touch issues of iPhone is a common phenomenon, many owner of iPhone have this experience, no matter you've met this problem before, or you're facing the problem now, you no need to worry too much, because Vip Pro Shop Team sums up some of the ways to repair iPhone touch problems,  please see the following share.

 
Specific maintenance methods: 

1. Replace iPhone LCD assembly to test;

2. Measure whether positive and negative 5.7V and 1.8V power supply on iPhone black touch is normal;

3. Measure whether 5.1V and the 1.8V power supply on iPhone white touch is normal;

4. Measure whether resistance of each touch J2401 pin to the ground is normal;

5. If all above the tests are normal, some repairmen will begin to remove black and white touch, and measure their respective resistance to the ground, if both are normal, they will begin to reinstall or replace the black and white touch IC to test.

The above maintenance method can eliminate a considerable part of the touch fault, our previous maintenance articles have also been described in detail. Today we want share the case: if the apple display fault is completely normal, the measurement of black and white touch to ground are all normal, chip and all power supply are also normal, but only the touch has no reaction, of course we are not going to talk about screen fault.

Apple IN-CELL, OGS and ON-CELL technology began to be used respectively from the 5 generation touch screen LCD, which is to say the screen and display are made together, rather than the early 4 generation and 4S, touch and display can be separated, these three technologies have a common characteristic: if the touch circuit not working at the same time will affect the normal working on display, also, the abnormal display part will affect touch.

6P touch screen function sometimes works but sometims not, the occasional white beating phenomenon in the upper part of the screen, which often caused by touch IC U2402 M1 pin faulty weld or disconnection, the article has described before. Today we are talking about is the same fault phenomenon at different fault parts. First, look at 4-2-1, U2402, 4-2-2,  where the M1 pin on U2402 leads to?

From picture 4-2-3 and 4-2-4, we can see the black touch IC U2402 M1 pin respectively lead to CPU E3 pin and inductance FL2034 2 pin, but FL2034's 1 pin is leading to diplay J2019's 18 pin.

And what's the function of J2019's 18 pin? Let's see the schematic diagram in picture 4-2-5. The information marked on the schematic diagram, it's the sync control signal that the screen is sending to the CPU.

Its normal resistance to ground is 420,  when it normal works, we get the waveform from oscilloscope as picture 4-2-6. This waveform is only can be measured when touch screen, display closed and screen is bright, this is a standard synchronous signal waveform.

 

From the schematic, we get a message: only display is normal so that a standard sync signal to the CPU E3 pin and black touch IC U2402 M1 pin can be outputed. In actual maintenance, a part of damaged machine shows normal but cannot touch, not all caused by black IC U2402 M1 touch pin fauty weld, but because FL2034 was hurled to the sealing off, the fault is covert.

Because the part of the motherboard accessories is sealed by glue, although there is glue injection, but also possible to fall off. It's easy to be ignored, so when measure touch the fault of 6P,  Besides measuring touch resistance, you'd better measure if there is normal resistance value on display 18 feet . As shown in figure 4-2-7.

Through this example we can also measure touch fault on iPhone 5, 5S, 6.

For iPhone 6, the synchronizing signal signal that display sends to touch  IC and CPU is display J2019 's 12 pin,  FL2034 inductor is easy to fall off . As shown in figure 4-2-8.

For iPhone 5s, the synchronizing signal signal that display sends to touch  IC and CPU is display J5 's 11 pin,  FL34 inductor is easy to fall off . As shown in figure 4-2-9.

For iPhone 5, the synchronizing signal signal that display sends to touch  IC and CPU is display J5 's 17 pin,  FL34 inductor is easy to fall off . As shown in figure 4-2-10.