IPhone 7

{|class="wikitable" ! style="text-align:left;"| Problem ! Solution


 * No Power -> Pulls 2A or more before you prompt to boot on DCPS
 * Do a full visual inspection of the board and check for water damage under the stickers on the back. Remove the foam around the connectors to get a better look at everything. You're looking for any signs of corrosion on or around components and ICs.
 * Do a full visual inspection of the board and check for water damage under the stickers on the back. Remove the foam around the connectors to get a better look at everything. You're looking for any signs of corrosion on or around components and ICs.

If there is no water damage, is is most likely a shorted capacitor on any of the below lines:


 * PP_VDD_MAIN This is the most likely line to be shorted
 * PP_VDD_BOOST This line is usually shorted when it's not VDD MAIN
 * PP_LCM_BL_ANODE or PP_LCM_BL34_ANODE Sometimes the backlight circuit has a short and causes the same symptoms
 * PP_SPKR1_VBOOST This is a bit rare but it does happen

You'll need to inject voltage (4V / 2A) directly into the line you measured as short and use freeze spray (see here https://youtu.be/3MtLSQJvQxI) or thermal camera (see here: https://youtu.be/fkd4iDjgfvc) to spot the capacitor that is shorted.

In these cases, you can just remove the shorted capacitor and not replace it. The device will function normally with no negative effects.

Replacing it means you are adding more heat to the board to reinstall it, which increases the risk of something going wrong.

If you have a case of water damage, then you'll have to pay attention to the spots on the board where there's signs of water damage.

Often, you'll find corrosion on capacitors but also under ICs.

Common ICs and areas to have corrosion and cause a VDD MAIN short:


 * Under BBPMU_RF and around it, like Capacitors: C5625_RF, C5622_RF
 * Back top "arm", like C2611, C2612, C2609, C2610
 * Back bottom, like the backlight caps C3725, C3705, C4602, C4612
 * Above and next to WiFi (WLAN_RF), like C7610_RF, C2527, C3002
 * Front Top above CPU, like C3327, C3328, C3313

You'll need to visually inspect these areas to see if they're liquid damaged

Please Note: If you are using a DCPS to inject voltage through the battery connector, like using an iPower Pro or DT880 (see here https://youtu.be/rawjB9yxe1A), be aware that the Tigris Mosfet Q2101 will heat up instantly. This is because the battery connector line PP_BATT_VCC connects to PP_VDD_MAIN through it, which creates lots of heat. Q2101 itself does not have a connection to ground, therefore, it's impossible to be shorted.
 * Not Charging -> Turns on but doesn't charge. Takes 0.006A via USB Charging Meter.
 * There are multiple ways to test and diagnose a charging issue/Tristar failure
 * There are multiple ways to test and diagnose a charging issue/Tristar failure

Step 1: Rule Out Parts Issues
Test the logic board with known good parts, like a known good charging port flex and battery.

These are parts that you have previously tested and confirmed they're good. Sometimes using just new stock is not enough, because sometimes new stock is defective.

Ideally, take the board out of the housing and only plug in a screen, battery and charging port to the logic board, then plug it in to charge and check the USB meter.

This helps remove all variables, as sometimes, a bad flex can cause charging issues, rare but it happens.

If the current is still around 0.006A via your USB meter, the phone turns on, but does not show charging symbol, then it's a board issue.

Generally, these scenarios are Tristar - U4001 - Part# 610A3B.

But to confirm, we need to do additional tests.

Step 2: Tristar Testers (optional)
You can use a tool called "Tristar Tester", which generally works well with detecting a bad Tristar, although it's not foolproof.

These two are the most popular on the market


 * Smartmod Pro Tristar Tester
 * ICC Pro Tristar Tester

Both scan for charging port issue, then Tristar issue.


 * If either say "Tristar Fail", it's a super high chance it's Tristar (see video at 4:21 https://youtu.be/KAMpmxeaNys?t=261)
 * Although, a "Tristar Pass" can still be a bad Tristar.

Use this as one of your clues to a bad Tristar, but don't trust it to be 100% accurate.

In either case, you can continue the diagnosis process to help further confirm a Tristar issue

Step 3: DC Power Supply Boot Up Consumption
With a DC Power Supply or DT880, see what is the power consumption before and after prompt to boot.

If you get current draw before prompt to boot, then it's not Tristar. See above Problem/Solution, as it will be a short on the board.

If you don't get current draw before prompt to boot, but after you prompt to boot, the first number of the current draw of the boot sequence is 0.1500.250A, then it definitely points towards a bad Tristar (see video at 6:39 https://youtu.be/KAMpmxeaNys?t=399).

Step 4: Check Tristar for Heat (Optional)
You can also use a thermal camera or freeze spray to check if Tristar heats up when you prompt to boot. Usually it will get hot when it's bad, but not always.

Step 5: Check Voltage at the Battery Connector
Plug in the charging port flex to the logic board, and nothing else. No screen, no battery, etc.

Then plug in the charging cable to the charging port.

Get your multimeter, set it to DC Volts mode, and measure the positive and negative battery pins of the battery connector J2201.

These are the 2 large pins on each side.

Polarity for this test doesn't matter, just ignore the negative symbol if you end up probing in reverse polarity


 * If the voltage is lower than around 2V, then Tristar is bad. Usually around 0.3000.600V
 * A working charging circuit will show about 3.7V

Replace Tristar
After all these tests, you can replace Tristar and see if it's solved.

Tristar for iPhone 7 and 7 Plus requires the version 610A3B. Please make sure to use the correct version, as previous iPhone models use slightly different versions of Tristar.

Please Note: Tristar on iPhone 7 and 7 Plus is partially covered by a shield. It is highly recommended that you don't touch the shield. You should be able to pull off the chip at an angle and place the new Tristar at angle. (See video at 13:22: https://youtu.be/KAMpmxeaNys?t=802)

Cutting the shield to get full access to Tristar will risk damaging surrounding components. Also, cutting the shield creates sharp points on the shield, which tend to stick out. This will cause the shield to cut or pierce through the charging port when you put it back into the housing, which will cause No Charging again.

After Replacing Tristar
Once you replace Tristar, you can follow the same steps from above to confirm if it's solved.


 * Check USB Charging with just your known good screen, battery, and port. It should be what a known good charging iPhone looks like. Generally 1A or more.
 * Run the Tristar Tester tool again (if you have one) and see if it passes now
 * Check the first number after you prompt to boot. It should be around 0.045A
 * Check if Tristar still heats up with freeze spray or thermal camera
 * Check if the voltage at the battery connector is at 3.7V, per Step 5 above

You'll want to compare you previous results to the new results. This tells you if the issue was solved or there's a problem still present on the board.

Please note: Each charging brick is slightly different, so it is recommended to get familiar with your charging brick and cable. Each cable and brick will give slightly different USB Charging Current readings based on the specs of the Current Output. You can read the charging brick itself to see the specs.

You can get a known good iPhone of the same model and see what the USB Charging Current is.

Then compare to the device you are repairing to see if it's about the same.

Also, close to fully charged batteries will charge at a lower current, than a low battery.

As well as old/worn out batteries charge at lower rates, as they're degraded and can't take a full charge.

Other Possible Charging Faults
If it still doesn't charge after replacing Tristar, make sure you followed all the troubleshooting issues above.

Then, you'll want to check for shorts around Tristar.

You can probe both sides of each capacitor that's directly surrounding Tristar and check for continuity to ground.

It's possible that TRISTAR_BYPASS capacitor C4005 is shorted to ground. It is recommended to replace.

C4005 value: 1.0, 6.3V, 0201 package

You can also remove Tristar and diode mode all the Tristar pads.

Compare the readings on your boardview software, like ZXW to your board.

You can also compare diode mode readings to a known good board.

If you find any shorts, you'll need to inject voltage to find the shorted capacitor.
 * Audio IC Issue -> Grayed out speaker button during a call
 * Audio IC Issue -> Grayed out speaker button during a call

Voice Memo app doesn't record

No sound in certain apps

Mic doesn't work for Siri

Lightning to 3.5mm headphone jack doesn't work

Lightning headphones don't work

Some people also call this "Audio Disease"

On older iOS versions, the device will get stuck on Apple logo for 7 minutes but then boot up fine and work, but experience audio issues.

Diagnosing
These are the two of the best steps to diagnose the Audio IC failure.

1. Make a call



 * If the phone has been experiencing audio issues and you have a supported SIM card available, the first thing to do is make a call and see if the speaker button is grayed out.


 * Calling 611 is the easiest option, as it is the universal phone number for the carrier's customer service. This will allow you to test the speakers, as there is a recorded voice on the other end of the call.


 * Usually, the speaker button will be grayed out if the Audio IC issue is present.


 * Sometimes, the speaker icon won't be grayed out, but there will be no audio out the ear speaker.


 * Or sometimes the speaker icon can be enabled, but just turns off within seconds. You turn it back on and it turns off again.

Please Note: Bluetooth audio, including AirPods, will still work fine when an iPhone 7 or 7 Plus has Audio IC issue present.

2. Voice Memo App



 * If you don't have a supported SIM card available, you can also use the Voice Memo app.
 * Depending on iOS version, you will have different symptoms here.
 * iOS 11 and older, the voice memo app will have a grayed out record button
 * iOS 12 will show "Recording Failed, No audio devices found" pop up when you click record.
 * iOS 13 and 14 will allow you to click the record button, but nothing happens. No recording starts. (See video at 0:28 https://youtu.be/IoGEWsZtOiE?t=28)  (Also see iOS 12 vs iOS 13 behaviors here: https://www.instagram.com/p/B3IUb6qnm4T/)
 * Sometimes, the voice memo app will allow you to record, even though the user has experience intermittent audio issues.
 * In these cases, you can start recording a voice memo, while at the same time, gently twisting the frame for 510 seconds. Then playback the recording
 * If Audio IC issue is present, you'll hear the playback audio with distortions and abnormal sounds.

Solution
Warning: Attempting this repair without enough experience with microsoldering, may lead the a "Baseband" issue, where you have "No Service" or non-stop "Searching..." issue. Proceed with caution.

Reball Audio IC U3101 and add C12 and D12 Jumpers
The reason why the Audio IC issue occurs is due to the C12 and sometimes the D12 pads under the IC will break. Both of these pads are critical for the audio function of the phone to work. If either of these pads are broken or loose, you'll get the symptoms mentioned above.

Making these 2 jumpers are critical to permanently solving the Audio IC issue, regardless if the pads break during IC removal or prepping the pads with your iron. Do not skip this step.

Sometimes, you'll run into a case where H12 and/or J12 will also break when removing the IC or prepping the pads, but these two pads do not cause the symptoms described above. If either of these two break, it would cause no audio through the lightning port, like using headphones through a lightning to 3.5mm headphone jack adapter.

Adding jumpers for H12 and J12 is optional.

Making The Jumpers Under Audio IC U3101
See example jumpers:

C12

 * Scratch out the trace that goes from C12 to R1103.
 * Zoom in close enough to see the trace and use a blade to gently scratch out that trade.
 * Then tin the trace
 * Install jumper wire
 * Add UV Mask to hold the jumper in place.
 * See video at 20:35: https://youtu.be/jr5lvCFTgoo?t=1235
 * The C12 pad may or may not break off, but the jumper wire must take up the space where the C12 pad would sit, to ensure the solder ball on the IC makes contact with the wire.
 * Some people prefer to keep the wire straight across like in the example image here
 * Some people prefer to curl the end of the wire so it makes a "J" shape or coiled shape.
 * In either case, it will work.

D12

 * D12 is a bit rare to break off, but it does happen, so it is recommended to jump this to avoid any warranty issues in the future
 * There are many places you can jump D12 to, but the most practical being to jump to G12
 * You can achieve this by make the jumper in the shape of a staple, by attaching the jumper to the pad, go up, then 90 to the right, then 90 down to G12
 * Make sure to give a lot of clearance and not have the jumper wire to close to the surrounding pads
 * Make sure to not let the jumper wire touch the components above it either.
 * No need to scratch out any traces in this case.
 * Add UV Mask towards the top of the jumper wire. This will hold the jumper in place
 * See video at 12:14: https://youtu.be/IoGEWsZtOiE?t=734

The final result should look something like this:

Other Jumpers

 * If F12, H12, J12 or any other pads rip, follow the path of each pad and solder the wire to that component
 * F12 should run a jumper to C3220
 * H12 should run a jumper to R3103
 * J12 should run a jumper to R3104

The Audio IC Chip - Reuse or Replace?
Please note: The root cause of the Audio IC issue is not caused by a bad Audio IC chip, so replacing it is not required. You can reuse the same IC by reballing the IC and placing it back once the jumpers are installed.

Sometimes, the IC gets damaged during removal and you will experience these issues:


 * Voice Memo App will record just fine and play back fine
 * Speaker button is not grayed out and working, but only bottom loudspeaker works. If you turn off speaker mode, the ear speaker will have no sound.

In this case, replace the IC and that should solve the no ear speaker sound after Audio IC repair attempt.

If you experience No Power or Overheating, then try removing the IC and test again.

Be aware that the phone will boot without the Audio IC installed. So if the phone boots up without the Audio IC installed and doesn't overheat, then this confirms the Audio IC chip itself went bad somewhere in the process.

Replace the Audio IC in this case.

Underfilled Audio IC
If you come across an Audio IC that is underfilled, it is recommended you just replace the IC, as it will be difficult to reball the original and most likely damaged during removal.

An underfilled IC is one that has black "glue" holding down the IC. It is believe that Apple started doing this on certain batches to help cover up the widespread Audio IC Issue.

You see the whole process of removing the Underfilled Audio IC here: https://www.youtube.com/watch?v=jr5lvCFTgoo

Final Testing

 * 1) Test Voice Memo App and make sure the app is recording your voice.
 * 2) Play back the audio recording and verify you get sound out of both the ear speaker and bottom loud speaker.
 * 3) iPhone 7 and 7 Plus has stereo sound, so the ear speaker and bottom speaker will play sound of them at the same time when playing back any Voice Memo recording.
 * 4) If you notice the ear speaker sound has static/distortion, check the ear speaker mesh. If it's dirty, it will cause this issue.
 * 5) Clean out the ear speaker mesh to solve it
 * 6) Make a phone call and verify the ear speaker has sound and make sure the loud speaker has sound.

If all tests look good, then the issue is solved.
 * No Backlight Or Half Backlight (Dark Spot in a corner)
 * No Backlight Or Half Backlight (Dark Spot in a corner)

You'll want to check these first to confirm you have a board issue:

 * Get a known good screen - Helps validate that you have a board issue.
 * Check USB Charging Current - If an iPhone shows proper charging current (~1A via USB or more), then mostly likely the device is alive.
 * Listen to for any sounds or vibration - Helps confirm if the phone powers on.
 * Turn off the phone, then plug in the charger & use a flashlight onto the center of the screen, to look for the Apple Logo - This helps confirm you are getting image, but no backlight.
 * Check for water damage. Often times, the backlight circuit gets hit the hardest in water damage cases.

Solution
In most cases, no backlight is caused by blown filters on the backlight circuit.

Most commonly it's due to these Filters

iPhone 7


 * FL3903
 * FL3901
 * FL3902

iPhone 7 Plus


 * FL3901
 * FL4601
 * FL3903
 * FL4602
 * FL3902

You'll need to use Diode Mode on your Multimeter to find the blown filter. (see video for the full process of diagnosing the backlight: https://www.youtube.com/watch?v=K-FFSMiHXPw)

Since backlight comes from the LCD connector, this is the connector you want to check the diode mode readings.

Essentially, you're comparing the diode mode values of a known good board vs your problematic board.

Most boardview software, like ZXW, will provide the known good diode mode values & you can use that as reference.

Expect to see a small ±5-10% variance of what you get.

With a backlight issue, you should find a pin on the LCD connector to read OL, when it should be giving you a diode mode reading. This line with the OL is what you want to investigate further.

These are the lines to expect to find an issue


 * PP_LCM_BL_CAT1_CONN
 * PP_LCM_BL_ANODE_CONN
 * PP_LCM_BL_CAT2_CONN
 * PP_LCM_BL34_CAT1_CONN - (iPhone 7 Plus only)
 * PP_LCM_BL34_ANODE_CONN - (iPhone 7 Plus only)
 * PP_LCM_BL34_CAT2_CONN - (iPhone 7 Plus only)

Also, sometimes, you can get lucky & visually spot the blown filter, but it's recommended to use your multimeter to confirm it's bad, as well as check the rest are good.


 * A good/working filter will have continuity across it & will have the same diode mode reading on both sides


 * A blown filter will not have continuity across it. In diode mode, you'll find one side has a diode mode reading & the other side will have either OL or a reading that is a larger value than what it should be.

The replacement filter should be the same value of the original.

You can see the values in the schematic or boardview software like ZXW.

Please Note: Never use a jumper wire as a replacement for a filter. This can permanently damage the phone if a surge in current occurs and there's no filter to protect the circuit.

Once you replace the filter, check that you be able to diode mode the connector again & find that the pin that was reading OL, is now giving you a proper reading.

Now you can test again & confirm the backlight is working again.


 * Random crashing
 * Bad battery / corrupted NAND / small shorts
 * Caps on PP_GPU_VAR / PP_CPU_VAR / PP0V9_SOC_FIXED get really hot
 * Most likely a short under the CPU, might be caused by itself, or improper hot air operation.
 * No IMEI, can't connect to cellular.
 * Baseband chip got lifted due to flex damage, or the baseband power IC failed and needs to be replaced.
 * Short on PP_VDD_MAIN
 * Shorted capacitor
 * Missing power lines
 * Reball/replace U1802, the Power Management IC
 * No vibration
 * Confirm that your charging port and Taptic engine are functional, then try replacing U3502.
 * Backlight functional, but no image
 * This is a common service error if you short something into the display connector, check the L3901, L3902, L3903
 * Phone Will Restart When You Make a Phone Call
 * No vibration
 * Confirm that your charging port and Taptic engine are functional, then try replacing U3502.
 * Backlight functional, but no image
 * This is a common service error if you short something into the display connector, check the L3901, L3902, L3903
 * Phone Will Restart When You Make a Phone Call
 * This is a common service error if you short something into the display connector, check the L3901, L3902, L3903
 * Phone Will Restart When You Make a Phone Call
 * Phone Will Restart When You Make a Phone Call

Symptoms:
When you make a call, the phone will instantly restart or shut off.

Testing & Solution:

 * Unplug the Front Facing Camera, then test again
 * If the issue is solve, then plug in a new Front Facing Camera flex & try again

Explanation:
Usually this is caused by the ALS or Proximity sensors getting some corrosion from liquid damage.

It's easier to just replace the part, but sometimes, you can clean off the corrosion with a toothbrush and isopropyl alcohol & get the flex working again.


 * Rear camera black image / bootloop when connected
 * Check the flex cable for damage, FL2500 and nearby components might be corroded.
 * Home button makes "farting" noise when pressed.
 * Check the Taptic engine and make sure the screws are not loose. If loose, tighten them.
 * }
 * Check the Taptic engine and make sure the screws are not loose. If loose, tighten them.
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