[SOLVED] I'm looking for LG K350K K Series repair guide or schematics (free) - Phones & Tablets Forum

Hi,

I'm hoping you can help me out with my LG K350K K Series. 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.

@Alberto

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 K350K K Series 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/273270/How+do+I+reset+my+BIOS+password+on+newer+ASUS+laptops
Take a look at comment #78
Also, this : https://xdaforums.com/t/request-stock-firmware-for-particular-m8.2966655/.
You can also check this video starting from minute 10:

The LG K350K K Series 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 K350K K Series 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 K350K K Series 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 K350K K Series 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/has-anyone-replaced-their-trackball.545511/

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

In many phones, the headphone jack is not a standalone component but is often integrated into a larger flexible printed circuit (FPC) cable assembly. Capacitive Home Buttons (Some Android): No physical click, just a touch-sensitive area. These tools help identify the touch controller IC, its power rails, data lines, and associated passive components (resistors, capacitors, filters, coils). Taking an extra minute to organize screws will save you much more time and potential heartache during reassembly. This system includes an infrared camera, a flood illuminator (to project infrared light onto your face), and a dot projector (to project thousands of invisible infrared dots to create a 3D depth map of your face). Before diving into the repair, it's crucial to understand the distinction between the display panel (LCD/OLED) and the digitizer. Always double-check connections and, if possible, test with another replacement part if the first one doesn't work. Cleaning: If only minor dirt or corrosion is present, cleaning the flex cable and connector with isopropyl alcohol might restore functionality. Plastic Pry Tools (Spudgers): For separating components without scratching. Green/Purple Hues (especially after impact): A strong indicator of physical damage to an OLED panel. Frame Replacement: For severely damaged clips or a bent frame, replacing the entire frame/mid-frame is often the most effective solution. Inspect New Housing: Ensure the new aluminum housing is clean, free of defects, and matches your phone model perfectly. For ICs that manage USB data, check the integrity of the D+ and D- lines. If those fail, systematically move on to hardware diagnostics, isolating components, and using specialized tools. If the issue persists, flashing the stock firmware can address corrupted system files that might be misinterpreting sensor data or managing thermal profiles incorrectly. Read/write "system configuration" data (serial number, Wi-Fi/Bluetooth MAC addresses, region, etc., critical for Apple devices). Device Verification: Match the IMEI/serial number on the device with the documentation. Slow Web Browsing/Downloads: Pages load slowly, videos buffer constantly. Replacing dedicated gaming triggers is a medium-difficulty repair that can significantly improve the mobile gaming experience. In conclusion, "calibrating" a new smartphone earpiece speaker is predominantly about diligent hardware optimization and component sourcing for a typical repair technician. If applicable, secure the back panel or screen with any external screws (like Pentalobe screws at the bottom of iPhones). Pay close attention to power ICs, charging ports, and battery connectors, as these are common points of failure. If your phone was water-resistant, apply new, model-specific adhesive strips to the frame before re-attaching the display or back cover. If the issue is mechanical (e.g., no click), examine the physical button or dome switch under the flex cable for obstruction, wear, or damage. Use with extreme caution, as excessive heat can damage internal components or delaminate the frame itself. Many charging issues stem from external accessories or software configurations. Always work in a clean, well-lit environment, and ensure you have all the necessary tools at hand. This ensures the heat is distributed evenly across all solder joints, preventing one side from melting before the other. Understand Risks: Be aware that rooting, custom ROMs, and manual flashing carry inherent risks, including bricking. Therefore, replacing a swollen battery isn't just a repair; it's a critical safety measure.

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