[SOLVED] I'm looking for NOMU S50 Pro repair guide or schematics (free) - Phones & Tablets Forum

Hi,

I'm hoping you can help me out with my NOMU S50 Pro. 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.

@Luana

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 NOMU S50 Pro 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/410947/Replacement+Battery+Charge+Level
Take a look at comment #1659
Also, this : https://xdaforums.com/t/any-different.2325921/.
You can also check this video starting from minute 7:

The NOMU S50 Pro 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 NOMU S50 Pro 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 NOMU S50 Pro 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 NOMU S50 Pro 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/231333/How+I+can+turn+on+later+that+I+change+the+screen

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

Continuity/Diode Mode: Check these components for shorts or opens, comparing to boardview. It mandates careful, systematic visual inspection under magnification after safely disassembling the phone. The PMIC is the heart of a phone's power distribution system, regulating voltages for nearly every component. Access Button Bracket: Once the back panel is off, locate the volume button area. Physical Damage: Drops or impacts can damage the tiny sensor module or its flex cable. Color Calibration/Accessibility Settings: Some devices offer advanced color calibration settings (e.g., "Screen Mode," "Color Balance," "Accessibility" options) that allow users to manually adjust color temperature. Attempting such a repair without proper training can easily cause further, irreparable damage to your device. Thermal Expansion/Contraction: While modern phone materials are designed to withstand normal temperature fluctuations, extreme or rapid changes in temperature can, in rare cases, contribute to subtle warping over time, particularly if there are pre-existing structural weaknesses. Concept: JTAG is a standard for verifying designs and testing printed circuit boards after manufacture. Any remaining underfill residue on the pads or between them must be meticulously removed. These applications are highly recommended as they automate the process and often provide detailed instructions. An outdated operating system might contain bugs that lead to the System UI crashing. If the battery was critically low, the phone might be on but unable to power the display. Lint-free Microfiber Cloths or Coffee Filters: For wiping and ensuring no fibers are left behind. Microscope: Essential for precision work on tiny BGA components and pads. Safety Glasses: Protect your eyes from unexpected debris or potential battery events. Erratic auto-brightness: Screen is too dim in bright environments, too bright in dark environments, or flickers constantly when auto-brightness is enabled. Heat for Reballing: Gently heat the stencil and paste with the hot air station until the solder paste melts and forms perfect, shiny solder balls. New adhesive strips (optional but recommended): If you need to reseal the phone. As the wear progresses, the problems tend to become more persistent and severe, potentially leading to a completely blank screen, even though the phone itself may still be powered on and receiving notifications. Clear Camera App Cache/Data: Go to phone settings > Apps > Camera > Storage > Clear cache and Clear data. It requires a very steady hand, excellent vision (even with a microscope), and familiarity with micro-soldering. Normal Behavior: When searching for signal, the current draw should fluctuate within a specific range. Look for discoloration, pitting, or green/white residue on the cables themselves. Be mindful of flex cables connecting to the back cover (e.g., fingerprint sensor, wireless charging coil). Hard Reset: Perform a force restart specific to your phone model (e.g., Volume Down + Power for Android, Volume Up, Volume Down, then Power for recent iPhones). Full Reassembly: If the repair is successful, carefully reassemble the phone, ensuring all flex cables are connected, shields and screws are in place, and the casing is properly sealed. App Permissions: Check microphone permissions for apps you suspect might be interfering. Check Phone Messages: Look for any "Charging Paused due to High Temperature" messages. Cut small, thin pieces of high-density foam, soft rubber, or specialized adhesive foam (like 3M VHB tape) to the required size and shape.

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