[SOLVED] I'm looking for Cubot Tab KingKong S repair guide or schematics (free) - Phones & Tablets Forum

Hi,

I'm hoping you can help me out with my Cubot Tab KingKong S. 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.

@Marine

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 Cubot Tab KingKong S 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/q-screen.2954145/
Take a look at comment #1256
Also, this : https://xdaforums.com/t/captivate-beeping.950018/.
You can also check this video starting from minute 1:

The Cubot Tab KingKong S 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 Cubot Tab KingKong S 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 Cubot Tab KingKong S 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 Cubot Tab KingKong S 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/plz-help-unable-to-play-this-type-of-audio.3127841/

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

There's little more frustrating than settling in to watch a video on your smartphone, only to be met with muffled, distorted, crackling, or barely audible audio. They should have similar values (often around 0.5V, but varies by model). Crucial: Disconnect the battery flex cable from the motherboard as soon as the phone is opened, even if you couldn't remove it earlier. Modify system files like `build.prop` to change device properties (e.g., enable camera2 API, alter device model for app compatibility). Bent pins, corrosion from liquid exposure, or loose internal connections (e.g., a faulty flex cable connecting the port to the motherboard) can prevent proper communication. Solving Persistent Performance Problems: If your phone is chronically slow, buggy, or has inexplicable battery drain even after other troubleshooting. Incorrect Location: Touches are registered but at a slightly different location than intended. When you hold the phone to your ear, the screen turns off to prevent accidental touches (e.g., muting, hanging up, dialing numbers) and saves battery. External: Visually inspect the back of your phone, especially near the camera module or the top edge, for any signs of physical damage like cracks, dents, or bulging that might indicate damage to the underlying NFC antenna. Other Android Manufacturers (e.g., OnePlus, Xiaomi, LG - older models): Variable Voltage Check: With the charger connected and battery disconnected (or connected if safe), check for 5V (or higher for fast charging) at the VBUS line of the charging port connector on the logic board. Manufacturing Defects: Less common, but a component might be faulty from the factory. Patience and Magnification: Work slowly and use a magnifying glass or microscope. Brightness stuck: Auto-brightness is enabled, but the screen brightness never changes, remaining at a fixed level, requiring manual adjustment. Photos taken might appear uniformly soft, or only a small, specific area might be in focus while the rest remains blurred. After any liquid damage repair, always meticulously clean and inspect all ground connections. USB-C Port: For phones that use USB-C for audio, clean this port as well. Sensor Test Apps: While basic, dedicated apps like "Sensor Box for Android" or similar can provide raw data from accelerometers, gyroscopes, magnetometers, proximity sensors, and light sensors. A faulty FEM can manifest in various ways, from poor signal reception and dropped calls to, significantly, excessive power draw that rapidly depletes the battery. Replacement BMS flex cable (or a new battery cell if transferring the old BMS). Color distortion, where hues appear incorrect, washed out, or even inverted, can also be a strong indicator. For hardware troubleshooting, the phone needs to be carefully disassembled. Faulty Flash LED: The LED flash unit might be physically damaged or its power circuit is failing. Repeated insertion and removal of charging cables, coupled with everyday wear and tear, makes it highly susceptible to damage. Too much localized heat can damage the battery, display, or other internal components. If, after a factory reset and with the phone in its pristine software state, it still fails to connect to a specific Wi-Fi band, the likelihood of a hardware fault increases significantly. Screws and Shields: Unscrew all screws securing internal shields and covers. Bluetooth and NFC: If not in use, turn off Bluetooth and NFC to prevent them from scanning for devices. When the board layers are stacked, the angle of observation under a microscope can be limited, and tools might obstruct the view. Essential tools include precision screwdrivers (Phillips, Pentalobe/Torx), a plastic spudger, thin pry tools (e.g., guitar picks), a heat gun or hairdryer, isopropyl alcohol (90% or higher concentration), a lint-free microfiber cloth or cotton swabs, and possibly fine-tipped tweezers.

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