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

Hi,

I'm hoping you can help me out with my MTT Tablet. 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.

@Moha

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 MTT Tablet 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/323404/Cant+start+phone+setup+wont+connect+to+wifi
Take a look at comment #1691
Also, this : https://www.ifixit.com/Answers/View/68311/If+fan+in+noisy,+does+it+need+replacement.
You can also check this video starting from minute 5:

The MTT Tablet 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 MTT Tablet 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 MTT Tablet 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 MTT Tablet 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/funny-app-reviews.2610891/

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

Connect to the shorted rail: Carefully connect the positive lead of your power supply to a test point or a visible capacitor on the shorted power rail. This is essential for locating the DSP, understanding its power rails, data lines, and surrounding components. Bluetooth and NFC: If not in use, turn off Bluetooth and NFC to prevent them from scanning for devices. Screen Stays Off After Calls: After moving the phone away from your ear, the screen remains black, making it impossible to hang up or interact with the call. Final Test: Power on the phone and perform comprehensive tests, including touch screen responsiveness, display colors, and any other relevant functions. Replacing the SIM tray eject mechanism in a sealed, water-resistant smartphone is a challenging but achievable repair for those with sufficient patience and attention to detail. Potential for Aftermarket Quality Variation: While buying genuine OEM (Original Equipment Manufacturer) parts is ideal, they are often hard to come by for consumers and very expensive. Repeat this process until the display panel surface is perfectly clean and free of any adhesive or debris. Often, Kapton tape is used to shield any very sensitive components on the board. Therefore, simply replacing a blown fuse without investigating the root cause (e.g., a shorted component elsewhere) will likely lead to the new fuse blowing again. Also, verify that the issue isn't related to the audio output being redirected to Bluetooth headphones or a connected USB-C accessory. Flex cables are the circulatory system of a smartphone, carrying power, data, and signals between various components and the main logic board. Missed Call/SMS: Have someone call or text your phone while it's locked and idle. For iPhones, the display assembly opens from right to left like a book. SIM Ejector Tool: This is the standard tool that comes with most smartphones. Watch through the microscope as the solder balls melt and "collapse" into place, forming solid connections. Remove SIM Tray and SD Card: Ensure all external components are removed. While not directly identifying ghost charging, unusual battery drain can prompt further investigation. After application or curing, use a new, clean microfiber cloth to gently buff the screen. Approach this task with diligence, adhere to safety protocols, and meticulously follow each step to achieve a successful repair.## 10. Once external factors and basic software issues are eliminated, the focus shifts to the physical inspection of the motherboard. Changes in user appearance such as new eyeglasses, sunglasses, a mask, a new beard, heavy makeup, or a different hairstyle can confuse the system, particularly if the initial enrollment didn't account for these variations. Full Disassembly: Carefully disassemble the entire smartphone to remove the main logic board (motherboard). Fine Files/Sandpaper: To smooth out rough edges or burrs after straightening. Do not attempt this without specialized equipment and training, as you risk destroying the entire logic board. If using pre-cut adhesive strips: Carefully peel and apply the new adhesive strips around the perimeter of the phone's frame, ensuring all edges are covered. Once the phone is open enough to access the internal components, immediately locate and disconnect the battery flex cable from the motherboard. No Power/Boot Loops: Can indicate PMIC failure, SoC issues, or NAND storage corruption. In conclusion, encountering an "SD card damaged" error is a common problem with a range of solutions. Display/Digitizer Flex: Examine the flex cable(s) coming from the display assembly that connect to the motherboard.

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