[SOLVED] I'm looking for BBK Vivo Y937 repair guide or schematics (free) - Phones & Tablets Forum

Hi,

I'm hoping you can help me out with my BBK Vivo Y937. 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.

@Roy

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 BBK Vivo Y937 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/564572/%C2%BF+Qu%C3%A9+tipo+de+bater%C3%ADa+de+litio+es+la+que+utiliza+el+iPhone+6
Take a look at comment #589
Also, this : https://www.ifixit.com/Guide/Milwaukee+Impact+Wrench+9070-20+Motor+Field+Winding++Replacement/127420.
You can also check this video starting from minute 9:

The BBK Vivo Y937 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 BBK Vivo Y937 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 BBK Vivo Y937 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 BBK Vivo Y937 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/40691/How+to+dismantle+MBP+and+clean+the+keyboard+backlight+after+spill

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

Restart Router/Modem: Power cycle your router and modem (unplug for 30 seconds, then plug back in). Unscrew and Remove Components: Following your guide, unscrew any shield plates, camera modules, or other components necessary to access the logic board. Antenna Design: Ensure the new antenna is identical to the original; subtle differences can affect performance. Be extremely careful not to scratch the SoC die or surrounding components. You may be prompted to enter your PIN, pattern, or password to confirm. Don't carry it in your back pocket where it can be bent or put under pressure when sitting. Front Camera / Proximity Sensor / Ambient Light Sensor: Often on a single flex cable assembly. Ensure "Vibration for calls," "Vibration on touch," or "System haptics" are enabled. This repair essentially involves fully disassembling your phone and then rebuilding it into the new housing. If the motor appears damaged, consider replacing the motor along with the bracket. Avoid forcing it, as this can easily bend pins or damage the connector housing. Place the multimeter's red probe on a known ground point on the motherboard. If these fail, a careful hardware inspection, focusing on the flex cable connection, is the next step. Software Updates: Ensure your phone's operating system and modem firmware are up to date. Stereo Microscope: Crucial for precise work on tiny chips and inspecting solder joints. This is essential for proper re-soldering and alignment of the new/original can. Replacing a damaged plastic camera lens ring is a relatively straightforward repair that significantly improves both the aesthetics and long-term protection of your smartphone's camera. It's crucial to log raw angular velocity for all three axes (x, y, z). Replacing the power flex cable is a precise repair, but it's very satisfying once completed, restoring full control over your smartphone. Gentle Lift: Once the solder reflows, the connector will visibly "float" on the pads. ESD-Safe Mat and Wrist Strap: To protect sensitive electronic components from static discharge. By systematically working through software fixes first, you can often resolve the issue. By carefully following the appropriate steps for your specific device model, cleaning the camera lens thoroughly, and properly installing the new glass, you can restore your smartphone's aesthetic appeal and protect its sensitive camera components for years to come.The "ghost touch" issue on a smartphone is one of the most maddening problems a user can encounter. Disconnect the Battery: Once the phone is open, locate the battery connector on the motherboard. Excessive Heat: While often indicative of a short, sometimes poor grounding can cause inefficient power delivery leading to localized heat. After the reset, you'll go through the initial setup process as if it were a new phone. Restore Backup (Optional): During setup, you'll have the option to restore your data from an iCloud or computer backup. Evaluating smartphone PCB solder joint cracks is a challenging but essential part of complex smartphone repair. ESD (Electrostatic Discharge) Awareness: Although the phone should be reassembled, a basic awareness is good practice. You might notice your phone no longer holding a charge as long as it used to, unexpected shutdowns even with a seemingly adequate charge, excessive heating during use or charging, or even the battery physically swelling.

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