[SOLVED] I'm looking for LG G8X ThinQ repair guide or schematics (free) - Phones & Tablets Forum

Hi,

I'm hoping you can help me out with my LG G8X ThinQ. It's started acting up, and I'm looking for a detailed service manual with boardviews and schematics to properly diagnose and repair it. I need to take precise voltage measurements around the board, so having the right documentation would be very helpful.

Thanks in advance for your help.

Selected Answer

I actually found that service manual on a tech Discord server a while back. A really helpful member there shared a direct link to their blog and I've saved it. I'm happy to pass it along here. Hopefully, these boardviews and schematics help you fix your phone, just like they got me through my repair. Looks like we have the same model.

@Bonnie

Absolute legend! That's exactly the info I was searching for. This is going to save me so much time probing in the dark. Seriously, thanks a ton for sharing the link!

Hi there,

I also have the LG G8X ThinQ and just downloaded the manual you shared. I'm pretty new to board-level phone repair, and this is a bit intimidating with all the tiny test points and the schematics. Could you point me in the right direction on how to start troubleshooting this ? Any advice on the first few things I should check would be a massive help.

Thanks so much for your time

General advices: start by checking the voltage at the battery connector on the board. With a known-good battery connected, you should see a steady voltage between 3.7V and 4.2V. After that, a great next step is to check the main power management IC (PMIC) for shorts. Using your multimeter in diode mode, check for shorts on the large input capacitors surrounding the PMIC.

Here are a few useful references for troubleshooting your device:
https://www.ifixit.com/Answers/View/813675/Diagnostic+Mode+F8+stuck+at+C8
Take a look at comment #207
Also, this : https://xdaforums.com/t/unlock-bootloader-for-new-kernel.1671489/.
You can also check this video starting from minute 2:

The LG G8X ThinQ service manual and boardviews from the link above were exactly what I've been searching for. I couldn't find a complete, free copy anywhere else. Seriously, thank you for sharing this you're a lifesaver!

Hi everyone, I'm working on a LG G8X ThinQ with a no power issue and need some guidance with my measurements.
I'm detecting 3.3V on the VREG_MAIN line (pin 1 of the PMIC), which looks good, but I'm getting 0V on the VDD_CPU line (pin 8) where the schematics indicate I should see about 0.9V.
Since this is a core voltage for the application processor, could this missing rail be why the device shows no signs of life?
What's the best procedure to diagnose this further? Should I check for shorts on the CPU rail first, or look at the PMIC's enable signals?
I've already verified the main 3.3V and 1.8V power rails are present and stable.

My LG G8X ThinQ was working perfectly until yesterday when it suddenly went completely dead. Now it won't respond to the power button, doesn't vibrate, and shows no signs of life even when connected to a charger. I'm worried there might be a serious issue.

I have a decent multimeter, a basic soldering iron, and a healthy dose of patience. While I've successfully replaced iPhone batteries and charging ports, this will be my first attempt at actual diagnosis. The sheer density of BGA chips and microscopic components is honestly a bit overwhelming.

I'm particularly curious about the alcohol trick I've seen online where you apply isopropyl to the board and look for evaporation hotspots to locate shorts. Is this actually a reliable method for beginners, or are there better approaches I should try first with just a multimeter?

I learned this lesson the hard way last month with mine, it was declared "dead" by two different shops. The phone showed absolutely no signs of life - no charging indicator, no vibration, nothing. Before diving into complex board work, I decided to try one more basic test: wireless charging.

To my complete surprise, it actually heated up on the charging pad! This single discovery completely changed my diagnostic path. It turned out the issue wasn't with the main board or processor, but with the notoriously fragile USB-C port that had failed completely. A $15 replacement part and some careful soldering brought it back to life.

The moral? Always exhaust every external testing method before opening the device. Test wireless charging if available, try different charging methods, and don't assume the worst case scenario. Sometimes the most "dead" devices have the simplest solutions hiding in plain sight.

I suspect my issue might be related to that cheap, third-party fast charger I used at the airport last week... Now the device gets extremely hot during charging, the screen flickers at low brightness, and sometimes it randomly shuts down at 30% battery. Could this have damaged the power management IC or battery calibration?

If your LG G8X ThinQ starts acting up, random reboots, fast battery drain, or connectivity issues, there are several diagnostic steps you can take before assuming the worst:

• Check your charging habits: Using poor-quality chargers or wireless pads can gradually damage your battery and charging circuit, leading to unpredictable behavior.
• Inspect the physical components: A slightly damaged charging port, worn battery, or even accumulated pocket lint can cause issues that seem like major hardware failures.
• Monitor temperature patterns: If your phone gets unusually hot during specific tasks (like camera use or gaming), it could point to a failing component rather than a software issue.
• Use diagnostic tools wisely: Ampere for battery health, phone diagnostic codes (*#0*# on many models), and a thermal camera can reveal problems without opening the device.
• Know when to stop: If you see liquid damage indicators tripped or smell burnt electronics, it's time to consult a professional before causing irreversible damage.

Also visit this link it may help : https://www.ifixit.com/Guide/Acer+Aspire++E5-574-53QS+Back+Panel+Removal/132008

Here's what I discovered on forums and technical databases:

No Data Transfer: The phone is not recognized by a computer, or data transfer fails. Alignment: Carefully align the screen protector with the phone's screen, ensuring cutouts for the camera, speaker, and sensors are correct. If you have access to a replacement screen for your specific phone model, carefully connect it (without fully installing it) and power on the phone. Microphone Issues: If the jack supports a microphone (TRRS connector), the mic might not work or sound distorted. Practice on donor boards or broken screens before attempting on a customer's device. The presence and severity of thermal discoloration directly correlate with the degree of heat damage. Disable Security Software: Temporarily disable any antivirus, firewall, or VPN software on your computer, as these can sometimes interfere with Apple's servers or communication with the device. Hardware Confirmation: If a factory reset yields little to no improvement in benchmark scores or real-world performance, it strongly indicates a hardware issue with the NAND flash itself. The buzzing might change pitch or intensity with the processor's activity. Source an OEM or high-quality aftermarket replacement gasket specific to your phone model. Use cotton swabs, lint-free wipes, or a soft brush to gently scrub away residues. Does the buzzing appear, disappear, or change pitch/volume at specific brightness settings? Disclaimer: Opening your smartphone voids its warranty, carries risks of damage, and can be complex. Static Discharge: Always use an anti-static wrist strap or mat to prevent static electricity from damaging sensitive components. Apply a small amount of liquid flux around the edges of the Audio Codec IC. Reconnect the battery, replace any shields or brackets, and then re-attach the back panel (or whatever component you removed first). Internet Connection: Required for iTunes/Finder to download the latest iOS firmware file (IPSW). The gyroscopic sensor is typically a tiny MEMS chip, often integrated into a larger Inertial Measurement Unit (IMU) chip, or sometimes even directly into the main SoC. Physical Damage: Cracked screen, broken charging port, water damage indicators tripped, visibly bent frame. If the signal is worse, it might mean a contact point was completely missed or incorrectly installed. Multi-Microphone Testing: Test different scenarios (calls, recordings, video) to identify which microphone is affected. The first step in evaluating Wi-Fi authentication failures is to understand the symptom's specifics. Dust and Moisture Ingress: Cracks create openings for environmental hazards, compromising any water or dust resistance the phone originally had. The wireless charging coil is typically a thin, flat component located on the inside of the phone's back cover or adhered to the internal frame, underneath the back glass. Battery Drain: Corrupted files can cause processes to run in an endless loop or consume excessive resources, leading to rapid battery depletion. Gently apply heat to the exterior of the back cover, specifically over the camera bump area, to soften the adhesive. Over time, this foam can deteriorate, become clogged with debris, or even disintegrate, leading to muffled audio, excessive wind noise during outdoor recordings, or generally poor sound clarity. Resettable Fuses (Polyfuses or PTC Thermistors): These devices, typically called Polymeric Positive Temperature Coefficient (PPTC) devices, increase their resistance dramatically when overcurrent occurs, effectively limiting the current. Start with the "Bottom" Cables: If multiple cables are routed through the same area, begin by routing the cables that sit deepest in the chassis or are hardest to reach. Plastic is preferred to avoid shorting components or scratching delicate PCBs.

@Dennis, Not sure what you're trying to say but ok :)