[SOLVED] I'm looking for Infinix S3X repair guide or schematics (free) - Phones & Tablets Forum

Hi,

I'm hoping you can help me out with my Infinix S3X. 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.

@Erol

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 Infinix S3X 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/flashing-magisk-with-twrp-without-ramdisk.4465765/
Take a look at comment #1541
Also, this : https://www.ifixit.com/Answers/View/621449/How+do+I+get+out+of+PUK+mode.
You can also check this video starting from minute 5:

The Infinix S3X 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 Infinix S3X 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 Infinix S3X 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 Infinix S3X 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/xoom-updated-to-3-2-6.1496499/

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

LED Array: A series of small white Light Emitting Diodes, usually arranged along one or more edges of the display. Test on Another Device: The first and most critical step is to test the suspect SD card in another compatible device, such as another smartphone, a tablet, or a computer with an SD card reader (using an adapter if necessary). Disconnect Battery (CRUCIAL): This is the most important step when working inside any electronic device. For Thermal Paste (if chosen): Apply a tiny, rice-grain-sized dot of thermal paste to the center of the SoC. User-level fixes are virtually non-existent, and solutions typically involve professional hardware intervention or, if severe and persistent, a warranty claim. Suction cup and heat gun/hair dryer: To soften adhesive for screen/back panel removal. For troubleshooting and prevention, always handle the SIM tray with care. Feel and Click: Does the power button feel "clicky" and responsive, or is it mushy, stuck, or loose? A lack of tactile feedback can indicate a broken button mechanism. A new replacement battery: Ensure it is specifically designed for your exact phone model and purchased from a reputable supplier. Power Lines: The main positive and negative terminals connecting the battery cell to the phone's charging and power delivery circuits. Whether it's a digital crown or a side key, the fundamental components involved are similar: This provides a soft surface and helps prevent tiny parts from rolling away or getting lost. Manufacturing Defects: In some cases, components might not have been perfectly installed at the factory. This damage disrupts the electrical pathway, leading to display malfunction, intermittent connectivity, or complete display failure. Specifically, Section 17 of the Theft Act, dealing with false accounting, and Section 22, handling stolen goods, are relevant. Visual Scan: With magnification, carefully scan the area around the camera lens within the module. Current Limit: Set a reasonable current limit to protect both the phone and the power supply from severe shorts. However, with the right tools, techniques, and meticulous attention to detail, it's possible to revive a device that might otherwise be deemed irreparable. Start with recommended settings (e.g., 350-380°C for lead-free) and adjust. Gently Lift: Once all screws are removed, the display module can usually be gently lifted away from the main frame. Speakerphone Mic (Secondary): Test by using speakerphone during a call. Gentle Handling During Repairs: Always use plastic tools when prying connectors and be extremely careful not to apply excessive force to clips. Reduce brightness, enable adaptive brightness, or use dark mode/themes. Few things are as frustrating as a smartphone that won't charge or connect to a computer. Before fully reassembling your phone, it’s a good practice to perform a preliminary check. SIM/SD Card Tray Guide: The slot where the SIM/SD card tray slides into the motherboard and through the chassis. Reconnect the flex cable to the logic board, ensuring it "clicks" into place. Once the adhesive is in place on the frame, leave the top protective layer on for now. In conclusion, diagnosing smartphone boot errors related to a corrupt partition table is a complex task requiring methodical steps. This is often caused by rough handling during disassembly or reassembly.

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