[SOLVED] I'm looking for LG G7200 repair guide or schematics (free) - Phones & Tablets Forum

Hi,

I'm hoping you can help me out with my LG G7200. 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.

@Lynne

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 G7200 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/Canon+Vixia+HF+R70+SD+Card+Replacement/86944
Take a look at comment #884
Also, this : https://www.ifixit.com/Answers/View/592622/Home+button+sticks+and+rotates.
You can also check this video starting from minute 3:

The LG G7200 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 G7200 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 G7200 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 G7200 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/182607/My+internal+microphone+dead+after+replacing+hard+disk

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

Corrosion impedes electrical signals, causing intermittent or complete connection failure. Shielding/Component Removal: Remove any metal shields (EMI shields) that cover the area to be worked on. When using an oscilloscope, look for several key indicators of a communication fault: If the phone doesn't overheat in Safe Mode, a third-party app is likely the culprit. AF (Autofocus) Mechanism Failure: The autofocus system relies on tiny motors or actuators to move the lens elements. Use a Protective Case: A good case can protect against impacts that might damage internal components. Even seemingly simple tasks, such as stitching panorama photos, can be affected, resulting in wavy, misaligned images, as the gyroscope helps maintain a steady rotational path during capture. Be extremely cautious not to damage internal cables (e.g., display flex, fingerprint sensor). This is a complex, board-level repair requiring specialized equipment (microscope, hot air station) and microsoldering skills. It will typically need a complete firmware flash using manufacturer-specific tools (e.g., Odin for Samsung, QPST/QFIL for Qualcomm-based devices) or generic flashing tools, which will re-write the operating system and partition structure to the newly installed chip. They often come with multiple interchangeable lenses, offering a range of magnifications, typically from 1.5x to 10x, and some even feature built-in LED lights. This comprehensive guide will walk you through the process, ensuring you can restore your phone's sound capabilities. The oscilloscope can confirm if the baseband processor is attempting to communicate and if the SIM card is responding. Ceramic-backed smartphones are renowned for their premium feel, scratch resistance, and often unique aesthetic appeal. A low health percentage might indicate a dying battery, but software issues can also misreport this. Set Multimeter: Set to continuity mode (beeper) or low resistance range. It shows no signs of life (no screen, no LED lights, no vibration), cannot access bootloader or recovery, and is not recognized by a computer. Fine-Tip Iron: Use a fine-tip soldering iron (e.g., JBC C245-781 or Hakko T15-IL) at a controlled temperature suitable for lead-free or leaded solder. Gently nudge the IC with tweezers if it doesn't self-center perfectly. Sometimes, a component can become "underfilled" or develop a weak connection due to impact or thermal cycling. Method 3: Custom Recovery (TWRP) - More Advanced, Requires Unlocked Bootloader Continuity Checks: Verify continuity of coaxial antenna cables and their connections to the motherboard. These micro-fractures might not manifest immediately but can cause intermittent problems or complete failure later. Plastic Spudger: A versatile tool with various tips for prying, lifting, and scraping. You only want to remove the solder mask, not cut through the copper trace underneath. A working trace should show continuity (a beep or near 0 ohms resistance). This is typically an OEM process and not practical for post-repair application due to specialized equipment requirements. Very Dim or Black Screen, But Faint Image Visible: This is the hallmark symptom. High Wakelocks: Apps or system processes constantly preventing the phone from entering deep sleep. Adhesive Backing: The motor is directly glued to the chassis or a mid-frame.

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