[SOLVED] I'm looking for BBK Vivo X90 repair guide or schematics (free) - Phones & Tablets Forum

Hi,

I'm hoping you can help me out with my BBK Vivo X90. 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.

@Marion

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 X90 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/ois-not-working.4470425/
Take a look at comment #1292
Also, this : https://www.ifixit.com/Wiki/Panasonic_ARC_ES-LT3N.
You can also check this video starting from minute 6:

The BBK Vivo X90 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 X90 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 X90 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 X90 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/Guide/Aiper+Seagull+Pro:+Button+bearing+replacement/177344

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

Quality Control: Allows for the retention of the original OEM display panel, which often offers superior image quality compared to aftermarket full assemblies. Screen protectors, especially full-coverage or poorly applied ones, can sometimes cover the earpiece grille (which might house a microphone) or other small microphone holes, leading to muffled input. Slowly work your way around all four sides of the phone, reheating as needed, to carefully slice through the adhesive. If pins are shorted while the phone is on, it can cause severe damage to the charging IC or other logic board components. Therefore, "calibrating" a new earpiece speaker largely shifts to a focus on: Wi-Fi and Bluetooth may still work: Since these are handled by separate chips (Wi-Fi/Bluetooth IC), they usually remain functional, helping to distinguish baseband issues from other motherboard problems. If a generic replacement doesn't work, research if that specific model uses pairing. Faulty Display Panel: The display panel itself might have a manufacturing defect, age-related degradation (especially with OLEDs, where individual pixels can degrade unevenly), or internal component failure. Hot Air Rework Station (if soldered): Essential for safely desoldering and soldering surface-mount components to the motherboard. Toggle Wi-Fi/Bluetooth: Turn Wi-Fi and Bluetooth off, wait 30 seconds, then turn them back on. OLED (Organic Light-Emitting Diode) displays have become the gold standard for high-end smartphones, celebrated for their vibrant colors, deep blacks, high contrast ratios, and energy efficiency. If it has, power off, disconnect the battery, and proceed to full reassembly. Clean the Board: After soldering, clean the area thoroughly with isopropyl alcohol to remove any flux residue. Remove Mid-Frame/Shields (if applicable): Depending on the phone model, you might need to unscrew and remove a mid-frame, various metal shields, or internal components to gain access to the wireless charging coil and its surrounding magnet assembly. Remove the Port: Once the solder melts (it might take 30-60 seconds, or more depending on heat settings and board characteristics), gently nudge the port with your tweezers. Explain that the repair cost is disproportionate to the device's current value. Avoid globs, gaps, or getting adhesive into sensitive ports or sensors. Carefully reinstall the camera module(s) and reconnect their flex cables. Permissions: Apps might be using location services, camera, or microphone in the background without clear reason. This is typically a hardware defect at the transistor level and is rarely fixable without physical replacement. Apps with High Background Activity: Any app that shows a disproportionately high "Background Activity" compared to its "On Screen" time, or simply a very high overall percentage when you haven't been actively using it. This can lead to uneven melting of solder balls, cold joints, or thermal stress on the board. Drivers (PC Side): On a Windows PC, open Device Manager and check for any "Unknown Device" or devices with yellow exclamation marks under "Universal Serial Bus controllers" or "Portable Devices." Update or reinstall drivers as necessary. Precision Screwdriver Set: For internal disassembly if required (often necessary to fully separate screen and frame). Scenario 1: Soldering a New Component to Fresh Gold Pads (less common in rework, but good for understanding) You might need to add more adhesive or apply clamps for a longer period. Selective Conduction: Under heat and pressure, the particles deform and create reliable electrical pathways only where they are compressed between the corresponding conductive pads. Desoldering/Soldering: For logic board repairs, a hot air station melts solder, allowing for the removal and replacement of tiny surface-mount components like ICs, capacitors, and connectors. For an independent repair, if a specific component like the IR camera or dot projector is identified as faulty, the "repair" solution typically involves desoldering the paired, encrypted IC (integrated circuit) from the original, faulty TrueDepth module and carefully transferring it to a new, identical module. If your phone was water-resistant, apply new, model-specific adhesive strips to the frame before re-attaching the display or back cover.

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