[SOLVED] I'm looking for LG Q7 repair guide or schematics (free) - Phones & Tablets Forum

Hi,

I'm hoping you can help me out with my LG Q7. 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.

@Belen

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 Q7 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://xdaforums.com/t/mods-xposed-modules-root-on-lg-v20-on-android-9.4378047/
Take a look at comment #892
Also, this : https://xdaforums.com/t/closed.382712/.
You can also check this video starting from minute 9:

The LG Q7 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 Q7 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 Q7 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 Q7 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://xdaforums.com/t/gopro-quik-app-with-mi-pad-4.3921230/

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

Carefully align the display with the frame, starting from the top edge. Before placing a smartphone motherboard into an ultrasonic cleaner, meticulous preparation is crucial to prevent further damage. Damage to these guides, whether from a drop, careless previous repairs, or manufacturing defects, can lead to critical flex cable damage and subsequent component failure. If heavily clogged, a small amount of IPA on a lint-free swab can be used very carefully, ensuring no liquid seeps into the device. Component Seating: Verify that any new or removed components (e.g., battery, camera modules, daughter boards) are properly seated and secured. Compare with Another Device: If possible, compare sensor readings from your problematic phone with a known-good device of the same model using the same sensor test app. It connects to the phone's logic board via a flexible ribbon cable (flex cable) or directly through contact points. Beyond the obvious aesthetic blight, a cracked screen can impair touch functionality, introduce dead pixels, allow dust and moisture to ingress, and even pose a physical hazard with sharp glass shards. Coaxial Connectors: Ensure the tiny snap-on connectors are perfectly circular and not squashed, distorted, or have missing center pins. Fix Power Button: A faulty power button can prevent the phone from turning on. Immediately after any repair, especially if new creaks or looseness are observed. Use Plastic Tools: Always use a plastic spudger or even your fingernail (if clean and trimmed) to pry connectors. Ensure the surface is perfectly smooth and clean for the new mesh to adhere properly. Examples include JCID, iCopy Plus, QianLi Apollo, and other brand-specific tools for iPhone screen/battery/Face ID data transfer. Modern smartphones employ robust encryption methods to protect user data, making unauthorized access extremely difficult and often impossible for a standard repair shop. New Button Flex Cable: Ensure it is compatible with your exact phone model. When this critical component malfunctions, whether due to impact damage leading to a cracked lens, internal circuit failure resulting in blurry images, black screens, or an inability to focus, or even dust ingress, the photographic capabilities of your device are severely compromised. Computer: A Mac (running macOS Catalina or later for Finder, or Mojave or earlier for iTunes) or a Windows PC (with the latest version of iTunes installed). Protect your hands from chemicals and oils, and prevent fingerprints/oils from transferring to components. Example: "Disassembled screen with heat," "Disconnected battery," "Replaced charging port flex," "Cleaned liquid damage with IPA and ultrasonic cleaner for 10 min," "Tested screen functionality pre-assembly." These are often the first components to check, as they are common points of failure. Combined Issues: Remember that Wi-Fi and Bluetooth issues often stem from the same shared IC. A smartphone drop or impact is a leading culprit; the sudden force can dislodge the camera module's flex cable from its socket on the motherboard. If both stock and third-party apps exhibit AF issues, the problem is likely deeper. Power Off and Disconnect: If tests are successful, power off the phone and disconnect the battery and display cables. Bent or Damaged Pins: Carefully inspect the pins (contacts) inside both the male connector on the flex cable and the female connector on the motherboard. Performance might be sluggish, and the device might occasionally freeze or crash due to resource contention. Execution: The flashing tool sends firmware files to specific partitions on the phone's internal storage. Suction Cup: Helps to lift the screen gently once the adhesive is loosened. You should see your device's serial number listed, confirming it's recognized.

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