Fix iPhone X with Distorted Sound

- Start by giving the motherboard a good once-over. Make sure it looks good—no warping or water damage in sight.

- Next, pop the motherboard back into the phone and power it up. Head over to Settings > Sounds & Haptics, crank up the volume, and play some ringtones. Listen closely—there should be some sound coming through with a bit of noise.

- Start by measuring the circuits connected to the speaker on the charging port connector. Power off the phone and detach the motherboard. Use diode mode to check pins 1, 3, 5, and 45 on the J6400. The readings should be normal.

- Next, it's time to separate the motherboard for some deeper testing. Gently slice through the shielding paper using a Sculpture Knife. Heat up the motherboard on the Heating Platform to 165℃. Once it's nice and toasty at that temperature, carefully remove the logic and signal boards.

- Now, attach the signal board to the holder. Apply some rosin using the Soldering Iron at 365℃ and use solder wick to clean the bonding pad. Do the same for the bonding pad on the logic board.

- Gently scrape off the old thermal grease using a Sculpture Knife. Give the motherboard a good clean with some PCB Cleaner. Then, connect the signal board and logic board to the Testing Fixture to move on to the next step.

- First, hook up that Test Extension Cable. Close the Testing Fixture snugly. Now, plug in the charging port flex cable, and don’t forget the battery and display connections. For a quick boot-up, simply short the ground to pin 9 of the J4300. The phone should power on without a hitch!

- Head over to Settings > Sounds & Haptics to check the ringtones. If they play just fine, it’s a good hint that the noise problem comes from a tricky pseudo solder joint in the motherboard’s middle layer.

- Next up, we’re going to reconnect the logic board with the signal board. Start by reballing the signal balls. Place the signal board onto the Reballing Platform, align the Reballing Stencil perfectly, then spread a thin layer of low-temperature solder paste evenly. Finally, lift off the stencil carefully.

- Place that signal board on the Heating Platform and crank up the heat to a cozy 165℃. Once those solder balls start forming, power down and let the motherboard cool off for about 5 minutes. A little Paste Flux never hurt, so go ahead and apply some!

- Next up, align the logic board with the signal board. Keep the motherboard toasty on that 165℃ Heating Platform. When you hit 165℃, hang tight for 1 minute to ensure a snug fit. After that, turn off the heat and let the motherboard cool for another 5 minutes before removing it.

- Place the motherboard on the phone. Next, connect the display and the battery. Your phone should power up like a charm. Check the sound – it should be back to normal, no annoying noises. You're good to go!