[SOLVED] I'm looking for YESTEL S10 repair guide or schematics (free) - Phones & Tablets Forum

Hi,

I'm hoping you can help me out with my YESTEL S10. 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.

@Imran

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 YESTEL S10 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/891447/How+can+I+fix+My+ps5+controller+drift+on+the+left+joystick
Take a look at comment #1727
Also, this : https://xdaforums.com/t/wild-blood.1937272/.
You can also check this video starting from minute 3:

The YESTEL S10 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 YESTEL S10 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 YESTEL S10 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 YESTEL S10 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/android-vs-ios.1140102/

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

Understanding its nature, common triggers, and how to systematically pinpoint its source can help distinguish between a normal, albeit undesirable, operational noise and a symptom of a deeper issue. If the phone powers on or the issue resolves: The disconnected component (or its flex cable) is likely faulty or causing a short. The thriving smartphone repair industry has created a vast market for replacement parts, ranging from screens and batteries to cameras and charging ports. Before applying any external power (other than the multimeter's internal battery), you need to ensure no critical power rails are shorted to ground. Therefore, the general rule of thumb is to repair lead-free devices with lead-free solder and, if working on very old devices that were originally leaded, to use leaded solder. This helps to identify if image retention is more prevalent in certain color channels. Consulting device-specific repair guides, schematics, or board views is absolutely essential to accurately pinpoint its location and understand how it’s integrated. Charging Works in Safe Mode: Definitive proof that a third-party app is causing the conflict. Overheating Still Occurs: The thermal pad might be the wrong thickness, or there's still poor contact. In conclusion, replacing the display flex cable, which often involves replacing the entire display assembly, is a common yet intricate smartphone repair. They display real-time voltage (V), current (A or mA), and sometimes wattage (W) and accumulated charge (mAh). Perform thorough testing in different scenarios: calls, messages, notifications, and haptic feedback for screen touches (if applicable). The primary challenge in removing a broken charging port connector lies in its typical construction. Intermediate/Advanced Tools (Optional but Recommended for Regular Repairers): Procedure: Power off the phone, remove the SIM tray, open the device (back cover or screen removal depending on model), disconnect the battery. Modem/RF Circuits: During heavy cellular data usage, especially in areas with poor signal, the modem works harder and generates more heat. Common BGA chips found on smartphone motherboards that often require reballing include the Application Processor (AP, or CPU), NAND flash memory, Baseband processor, RAM, and sometimes Wi-Fi/Bluetooth modules or power management ICs (PMICs). Unexpected Shutdowns: The phone may spontaneously power off to prevent damage. To measure ambient pressure, the sensor typically requires a tiny, unobstructed hole or port on the phone's frame. Sometimes, a loose or partially disconnected flex cable can cause intermittent or localized touch issues. Check for continuity from these pins to their respective connection points on the motherboard connector. Excessive ripple indicates poor power filtering, which can be a source of EMI. For instance, after the initial spike, it might settle around 100-200mA as the CPU and RAM initialize and the bootloader loads from the NAND storage. Reseat the Connector: Carefully disconnect and then firmly re-seat the flex cable that connects the headphone jack assembly to the motherboard. Use cloud services, connect to a computer, or use an external drive for a comprehensive backup. If they are gone, it indicates a software issue within your previous setup or apps. Too Much Dust: If there's too much dust, it might be better to remove the protector, clean both the protector (if possible, with clear tape on the adhesive side) and the screen again, and re-apply. Note: This test usually requires disassembling the phone to get a clear view of the camera module, which carries its own risks. Align and Close: Carefully align the top edge of the new display with the phone's frame first, then gently lower the rest of the display into place. Reconnect Battery: Reconnect the battery flex cable, pressing it firmly into its socket.

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