[SOLVED] I'm looking for ONDA V919 Air CH repair guide or schematics (free) - Phones & Tablets Forum

Hi,

I'm hoping you can help me out with my ONDA V919 Air CH. 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.

@Recep

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 ONDA V919 Air CH 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-not-able-to-get-ota-updates-after-reverting-back-to-stock-rom-from-cyanogenmod-11.2631255/
Take a look at comment #1665
Also, this : https://xdaforums.com/t/apps-which-crash-on-galaxy-nexus-with-force-gpu-rendering.1372007/.
You can also check this video starting from minute 6:

The ONDA V919 Air CH 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 ONDA V919 Air CH 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 ONDA V919 Air CH 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 ONDA V919 Air CH 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/913015/Fix+intense+flickering+to+the+point+where+I+can't+see+my+screen.

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

Random Restarts/Reboots: The phone unexpectedly restarts repeatedly, often without fully booting into the OS. Electronics Retailers: Many large electronics stores (e.g., Best Buy, Staples, Home Depot in the U.S.) offer free electronics and battery recycling services. Display Installation: If you removed the old display and are reinstalling it into the new frame, clean all old adhesive residue from the display and the new frame. Shields and Brackets: You will likely need to remove small metal shields or plastic brackets covering connectors and the motherboard. Ambient Light Sensor Test (if applicable): Check if auto-brightness functions correctly by moving the phone between bright and dim environments. Improper disassembly can lead to further damage, void warranties, or even cause injury. Adhesives and Sealing Gaskets: While the goal is to soften adhesives, too much heat can over-soften them, making them gummy and difficult to remove cleanly. While difficult to directly test the effectiveness of EMI shielding without specialized equipment, you can perform basic functional tests. Any flux residue, dust, oils, or contaminants will be sealed under the coating, potentially causing future issues. No calibration is needed or possible in the traditional sense; you're just preserving the original part. This often involves removing the screen, back cover, and sometimes other components. It's the protective barrier shielding the delicate camera sensor and optics from dust, scratches, and moisture. When heat and pressure are applied, the particles form electrical connections between the traces on the flex and the corresponding pads on the glass, while the resin cures to provide insulation in other areas. Tools: Requires standard smartphone repair tools (precision screwdrivers, spudgers, heat gun/iOpener, suction cup, etc.). Remove Old Module: If cleaning and reseating failed, carefully remove the screws (if any) securing the camera module. Avoid Extreme Temperatures: Both excessive heat and cold can degrade battery health and performance. If nothing is visible even with a flashlight, then either the LCD panel, its data lines, or the display driver IC is at fault. DO NOT Apply Heat: Avoid blow dryers, ovens, direct sunlight, or microwaves. This isolation is crucial for features like NFC payments (e.g., Apple Pay, Google Pay), secure boot, Digital Rights Management (DRM), and secure identity verification. As the solder melts, the IC should subtly "snap" or "settle" into its correct position due to surface tension. Motherboard Holding Fixtures (Fixture): Robust metal frames with adjustable clamps that hold a smartphone logic board perfectly flat and stable under a microscope or hot air station, preventing warping during rework. Check Card for Physical Damage: Inspect the SD card for any visible physical damage: cracks, bends, discolored contacts, or damage to the plastic casing. No sound from the main loudspeaker (for music, ringtones, speakerphone). Both the board and the chip are meticulously cleaned with Isopropyl Alcohol (IPA) to remove flux residue. While throttling reduces power consumption by lowering clock speeds, a phone that constantly hits thermal limits and then has to recover might experience inefficiencies. Final Reassembly: If the new display works flawlessly, power off, disconnect the battery, apply new adhesive strips to the phone's frame, and carefully re-seat the display. Search for these error messages online, as they often point to known issues or specific components (e.g., file system corruption, incompatible partitions). Fix Power Button: A faulty power button can prevent the phone from turning on. Gently disconnect and reseat it, ensuring it's flush and fully engaged. Removing the SIM card tray is also a necessary preliminary step, as it often helps secure the phone's casing.

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