[SOLVED] I'm looking for LG G5 F700S LTE-A repair guide or schematics (free) - Phones & Tablets Forum

Hi,

I'm hoping you can help me out with my LG G5 F700S LTE-A. 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.

@Ekaterina

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 G5 F700S LTE-A 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/Guide/NZXT+H510i+ATX+Mid+Tower+Power+Supply+Replacement/138823
Take a look at comment #1628
Also, this : https://www.ifixit.com/Guide/Samsung+Galaxy+S20+Plus+Motherboard+Replacement/136353.
You can also check this video starting from minute 7:

The LG G5 F700S LTE-A 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 G5 F700S LTE-A 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 G5 F700S LTE-A 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 G5 F700S LTE-A 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/Answers/View/340526/Why+doesn't+it+recognize+new+cartridges

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

Power Off Device Completely: Before opening your phone, ensure it is fully powered off, not just in sleep mode. Gentle Pressure Test: While the phone is vibrating or buzzing, gently apply pressure with your finger to different areas of the screen and back cover. OnePlus: Use their "Local Upgrade" option (if accessible) or Fastboot. Separate Storage: Place the taped battery in a non-combustible container (e.g., a ceramic bowl, metal tin) away from flammable materials until it can be taken to a recycling point. Alcohol Evaporation (Rosin/Freezer Spray): If a thermal camera is unavailable, apply isopropyl alcohol (IPA) liberally over suspect areas of the board. Lightly dampen the very tip of a cotton swab or a small piece of lint-free cloth wrapped around a toothpick with isopropyl alcohol. Remove Phone Case and Screen Protector: Technicians don't need these and they might get lost or damaged. Unlike older, robust camera lenses that often featured simple glass elements, modern smartphone camera lenses are highly sophisticated, compact optical systems. While some off-angle shift is normal for OLED, an excessive or immediate shift at only a slight angle is indicative of an issue. For very stubborn adhesive, you might incrementally go up to 100-120°C (212-250°F), but never higher without extreme caution. ESD Protection: Always use an anti-static mat and wrist strap when working with electronic components to prevent electrostatic discharge damage. It demands immediate action, meticulous disassembly, careful manual and ultrasonic cleaning with appropriate agents, thorough rinsing, and complete drying. It's also integral to many modern touch interfaces, providing tactile confirmation for actions like typing or using 3D Touch/Haptic Touch. Use isopropyl alcohol (90% or higher concentration) and a lint-free microfiber cloth or cotton swabs to thoroughly clean both the perimeter of the phone's frame and the corresponding edges on the back of the display assembly. Try wiggling them or gently cleaning around them with a soft brush (or a small amount of isopropyl alcohol on a cotton swab) to dislodge any debris that might be causing them to stick. Battery Health: Modern smartphones have built-in battery health indicators in their settings. `adb logcat`: (Android Debug Bridge) Provides a real-time stream of system-level messages, invaluable for identifying power management events, errors, or temperature warnings. Unfortunately, due to their delicate nature, flex cables are highly susceptible to tearing, creasing, or nicking during drops, liquid damage, or improper handling during repairs. While not strictly an intermittent charging issue, it often accompanies them. Secure: Re-adhere the flex assembly (if it had adhesive) and re-install any screws or shields removed earlier. Press a small piece of the putty onto the earpiece mesh, gently but firmly, then quickly pull it off. Position New Battery: Carefully align the new battery in the battery well, ensuring its connector aligns perfectly with the socket on the logic board. Check Accessibility Settings: Ensure Force Touch (or 3D Touch) is enabled and its sensitivity settings haven't been inadvertently altered. "Dual SIM Dual Active" (DSDA) phones are rare now but allow both SIMs to be fully active simultaneously. Specific Peripheral Failure: A particular component (e.g., camera, speaker, Wi-Fi) stops working, but the rest of the phone functions normally. People you call complain about excessive background noise, even in quiet environments. Use a suction cup and opening picks to carefully pry and separate the back cover from the phone frame. Software Adjustments: Some audio apps or system settings (EQ, balance) might allow for minor adjustments that can compensate somewhat, but these won't fix the underlying hardware phase problem. If the input voltage is missing, the problem lies further back in the power management. Soldering Iron (for soldered ports): With fine tips, temperature control.

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