[SOLVED] I'm looking for LG KE800 repair guide or schematics (free) - Phones & Tablets Forum

Hi,

I'm hoping you can help me out with my LG KE800. 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.

@Pauline

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 KE800 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/23232/how-to+on+uninstalling+apps+completely
Take a look at comment #268
Also, this : https://xdaforums.com/t/multi-window-button.2244618/.
You can also check this video starting from minute 7:

The LG KE800 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 KE800 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 KE800 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 KE800 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/660495/Scrolling+using+Crown+not+working+but+rest+functions+work

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

When one of these tiny solder pads detaches, the charging port loses its connection to the rest of the phone's circuitry, leading to charging failures, data transfer issues, or intermittent connectivity. Remember to keep your tools organized, clean, and practice safety always.## 8. Once the flex cable is disconnected, the next step is to remove the faulty button assembly. Disconnect Display & Battery: Once the screen is partially separated, prop it open (often like a book). Intensive Usage: Graphics-intensive games, 4K video recording, heavy multitasking, video streaming, long video calls, extensive GPS navigation. Heavy Usage: Are you running graphics-intensive games or multiple apps simultaneously? If the voltage exceeds a safe threshold (e.g., 6.5V for a 5V input) or if the current becomes dangerously high, the OVP IC will quickly disconnect the VBUS line, preventing the excessive power from reaching and damaging sensitive internal components, especially the PMIC and battery. Are they securely seated on both the motherboard (Wi-Fi module) and the antenna board/frame? Gaming: Play a graphically intensive game that pushes the phone's GPU. With the phone powered off and battery disconnected, you can perform a basic continuity test on the motor. Once the screen assembly is partially lifted, locate the battery connector on the logic board. This means not just turning off the screen, but performing a full shutdown from the operating system. Looking for recurring error messages related to specific hardware modules (e.g., "camera failed," "audio error," "kernel panic") can directly point to a conflict. However, by understanding the components involved, prioritizing a clean work environment, meticulously preparing surfaces, using high-quality replacement gaskets, and applying proper sustained pressure, a repair technician can significantly enhance a device's resilience against dust and accidental water exposure. Understanding the various types of wear and their potential causes allows for targeted troubleshooting and effective repair strategies. Compromised Structural Integrity: A severely bent frame, a cracked logic board, or catastrophic damage from a high-impact drop can make a stable repair impossible. Heat with Iron: Use a fine-tipped soldering iron at an appropriate temperature (e.g., 350-380°C for leaded solder). Tools that assist in reading schematics include dedicated software like ZXW Dongle, Wuxinji, or Phonefixbox, which often integrate boardview layouts with schematics. These LEDs are powered by a dedicated backlight driver IC (Integrated Circuit), which steps up the battery voltage to a much higher voltage required by the LEDs and regulates the current. Use isopropyl alcohol and a plastic scraper or tweezers to remove every last bit. Damaged Cable Guides: Broken guides can cause flex cables to be misrouted or pinched. Microscope: A stereo microscope is critical for inspecting the tiny components, reading their microscopic markings, and verifying their condition. The bristles should be able to dislodge superficial dust and grime without harming the mesh. Start by testing the SD card in another device to determine if the card itself is faulty. Follow up with short bursts of compressed air to dislodge any accumulated dirt, dust, or lint. This method involves applying gentle pressure to the pixel, sometimes combined with software. Go to `Settings > Network & internet > Mobile network > Preferred network type` (Android). This usually involves prying up a small ZIF (Zero Insertion Force) connector or a standard press-fit connector with a plastic spudger. Slow Wi-Fi/Bluetooth Speeds: Noticeable degradation in data transfer rates, making web browsing sluggish, streaming buffer frequently, and file transfers crawl. These are tiny and fragile; ensure they snap securely onto their ports without bending the pins.

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