[SOLVED] I'm looking for NUU A15 repair guide or schematics (free) - Phones & Tablets Forum

Hi,

I'm hoping you can help me out with my NUU A15. 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.

@Virginie

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 NUU A15 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/255489/What+is+the+maximum+size+RAM+upgraded+in+a+MacBook+Pro+13
Take a look at comment #384
Also, this : https://xdaforums.com/t/unable-to-adjust-brightness-after-replacing-display.1248522/.
You can also check this video starting from minute 5:

The NUU A15 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 NUU A15 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 NUU A15 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 NUU A15 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/verizon-customer-service-and-insurance-downgrade-to-note-2-questions.2417605/

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

These micro-cracks are a frequent cause of intermittent failures, unexplained shorts, or complete device death, and their elusive nature makes diagnosis extremely challenging. B-7000 or similar adhesive / Pre-cut adhesive strips (optional): For resealing the phone to maintain dust and water resistance. Diagnosing the root cause can be tricky, as flickering can stem from a wide range of issues, from simple software glitches to complex hardware failures. This will show you screw locations, adhesive patterns, and cable routing. At this point, it is advisable to seek assistance from a professional repair technician specializing in mainboard-level repairs, as attempting this without expertise can cause irreparable damage. Screw Still Loose: The repair method didn't hold, or the chosen adhesive wasn't strong enough. IMEI Storage: The International Mobile Equipment Identity (IMEI), the unique identifier of your phone, is typically stored within the baseband firmware. Replacing a damaged smartphone charging port is a rewarding DIY repair that can save you money and extend the life of your device. Check Continuity: Place one multimeter probe on a specific pad/pin on the flex cable and the other probe on the corresponding point at the other end of the flex cable (or the connector pin on the motherboard if checking the cable's connection). Voltage and Current readings, available in some diagnostic apps, can also be informative. Disassemble iPhone: Carefully open the iPhone, disconnect the battery, and remove the logic board from the frame. This manifests as intermittent issues that are incredibly difficult to diagnose. Ensure the wall adapter provides sufficient power (e.g., typically 5V/2A or higher). Testing: Professional battery testers can measure actual capacity, internal resistance, and voltage under load, providing a more definitive diagnosis. Clean Contacts/Connectors: Often, simply cleaning corroded or dirty antenna contacts with IPA and a brush can resolve the issue. Donor Board (optional but recommended): For salvaging components or practicing. Backup Data (if possible): If the phone is partially functional, back up any accessible data. For Bluetooth, it follows the IEEE 802.15.1 standard, facilitating short-range wireless communication with accessories such as headphones, smartwatches, car systems, and other smartphones for data transfer or tethering. Reflow Solder Balls: Use the hot air station (lower temp, e.g., 250-300°C, low airflow) to reflow the solder paste into perfectly spherical, uniform solder balls. A common test involves checking the resistance values around the audio IC's power management lines. If this chip is faulty or has damaged solder joints (often due to drops, overheating, or liquid damage), it can lead to intermittent or no charging. For DIY repair, replacing the entire display assembly (LCD/OLED + digitizer) is almost always the more practical and recommended approach. This is especially noticeable when starting navigation in an unfamiliar area. Always use high-quality replacement parts specific to your phone model. A successful repair extends its life; a failed one is less financially impactful. It transforms a functional repair into a complete customer experience, ensuring the device not only works flawlessly but also feels new and cared for. - Component Shift: After an impact or a repair, internal components might shift and press against the display. Connectors: Inspect the small snap-on connectors of the coaxial cables on both ends (logic board and antenna flex). Backlighting: Take a photo with a bright light source (e.g., the sun, a window) positioned behind the subject, directly facing the camera. Calipers are instruments used for measuring the linear dimensions of objects.

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