[SOLVED] I'm looking for CHUWI Hi9 Air repair guide or schematics (free) - Phones & Tablets Forum

Hi,

I'm hoping you can help me out with my CHUWI Hi9 Air. 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.

@Drew

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 CHUWI Hi9 Air 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/608344/Is+it+meant+to+be+able+to+play+music+under+water
Take a look at comment #160
Also, this : https://xdaforums.com/t/was-this-the-website-app-that-was-banned-from-the-market.550469/.
You can also check this video starting from minute 6:

The CHUWI Hi9 Air 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 CHUWI Hi9 Air 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 CHUWI Hi9 Air 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 CHUWI Hi9 Air 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/369505/What+is+the+reason+my+computer+is+showing+that+the+NTLDR+is+missing

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

Go to `Settings > Network & Internet > Mobile Network` (or similar, varies by Android version/OEM) or `Settings > Cellular` (iOS). For serious mobile gamers, features like high refresh rate displays, powerful processors, and advanced cooling systems are paramount. Fortunately, replacing this outer glass cover is a relatively straightforward repair for many smartphone models, though it requires precision and a dust-free environment to achieve optimal results. Disk Utility (Mac): On a Mac, open "Disk Utility," select the SD card, and run "First Aid." For Wi-Fi, it adheres to the IEEE 802.11 standards (a/b/g/n/ac/ax), allowing the smartphone to connect to local area networks, access the internet via wireless routers, and participate in peer-to-peer connections like Wi-Fi Direct. Insert a plastic spudger or a sturdy plastic card underneath the battery from the bottom or side. Solder Wick (Desoldering Braid): For cleaning residual solder from pads after removal. Disclaimer: Opening your phone voids its warranty and carries a significant risk of causing further damage. Only one audio channel working: Sound only comes through the left or right earbud, indicating an issue with one of the audio pathways. Avoid direct spraying onto the entire logic board unless it's designed for heavy wash-down (and then follow with an IPA rinse). `adb shell dumpsys batterystats` or `adb shell dumpsys battery` can give extensive logs about what's consuming power, including specific kernel wakelocks. Apple often releases software updates that include bug fixes, which might, in rare cases, address underlying software issues affecting hardware initialization. Use a bright light and a magnifying glass (or microscope) to perform a thorough, final inspection of the entire frame. Document Everything: Take photos at every step, especially of screw locations and component placements. Optimize Background Data: Restrict background data for apps that don't need constant internet access. Unlike a standard iTunes/Finder restore (Recovery Mode), DFU mode allows you to restore your iPhone's firmware without loading the operating system or bootloader, making it the deepest level of restore possible. For example, a file being actively worked on might save incorrectly, or a photo taken might appear garbled if the image data was corrupted in RAM before being written to storage. A shorted PA might cause an immediate high current draw upon boot, or prevent the phone from booting entirely. Diagnosing PMIC failures requires a systematic approach, a good understanding of power electronics, and the right tools. Lifted Pads: If the via is connected to a component pad, check if the pad itself has lifted. Loose Cable Connection: The charging cable feels loose in the port or easily wiggles out. If external checks and software troubleshooting don't fix the issue, the problem likely lies with the speaker module itself or its internal connections. Diagnosis Difficulty: Pinpointing the memory controller as the sole cause of a fault can be arduous, as many symptoms overlap with RAM or NAND failures. Earpiece Mesh: A fine mesh located at the top of the phone, where you hold it to your ear during calls. Locate and Disconnect: Once the power flex cable is visible, locate its connection point to the motherboard (if it's still connected) and gently disconnect it using tweezers or a plastic spudger. Inspect Under Magnification: Use a microscope or loupe to clearly see the bent pin(s). If the phone has recently been exposed to humidity or a minor splash, check for condensation inside the camera lens (front or rear) or under the display. Hold the frame up to the light and inspect it from different angles to ensure no shiny or sticky spots remain. Audio Codec: An IC that converts analog audio signals from microphones to digital data, and digital audio data into analog signals for speakers and headphones. Ensure all important photos, videos, documents, contacts, and any other irreplaceable data are safely backed up to a cloud service (like Google Drive, Google Photos, iCloud, or manufacturer-specific clouds) or transferred to a computer or external storage device.

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