[SOLVED] I'm looking for Samsung SM-S936N Galaxy S25 repair guide or schematics (free) - Phones & Tablets Forum

Hi,

I'm hoping you can help me out with my Samsung SM-S936N Galaxy S25. 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.

@Rob

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 Samsung SM-S936N Galaxy S25 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-problem-with-alcatel-ot-985.2059839/
Take a look at comment #937
Also, this : https://xdaforums.com/t/restore-to-stock-after-rooting-and-unlocking-bootloader.3474039/.
You can also check this video starting from minute 3:

The Samsung SM-S936N Galaxy S25 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 Samsung SM-S936N Galaxy S25 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 Samsung SM-S936N Galaxy S25 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 Samsung SM-S936N Galaxy S25 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/bricked-samsung-galaxy-note-8-0-shw-m500w.2512035/

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

Next, you will need to open the phone, which usually involves removing screws from the bottom (often Pentalobe or Torx) and then carefully prying open the display assembly from the frame. When an SoC generates heat, it needs an efficient way to dissipate that heat to prevent overheating, which can lead to performance throttling, system instability, and even long-term damage to components. Restart the Phone: A simple reboot can resolve temporary software glitches. This method involves applying gentle pressure to the pixel, sometimes combined with software. Branding & Certifications: Look for clear manufacturer branding, capacity ratings (mAh), and safety certifications (CE, UL, RoHS). By systematically testing for continuity, resistance, and voltage, you can logically deduce the cause of a malfunction, moving beyond guesswork to precise, component-level diagnostics. While less common in modern smartphones, if the device utilizes thermal paste (e.g., on a central processing unit under a heat spreader), inspecting and replacing degraded paste can improve thermal efficiency. Modern smartphones often boast impressive water and dust resistance ratings, typically expressed as an IP (Ingress Protection) code like IP67 or IP68. For many users, if the whine is minor and only audible in specific, low-load situations, they may choose to live with it. Approach: Install a robust battery monitoring app (like GSam or AccuBattery) and let it run for a day or two, through several charge cycles. If software troubleshooting and external inspection yield no results, the problem likely lies with the hardware. Diagnostic Apps: Re-run sensor diagnostic apps to verify that the accelerometer and gyroscope are now reporting correct, stable data. Misalignment: The sensor might not be perfectly seated behind its dedicated window on the display. Incorrect Functionality: Flashing the wrong firmware version or one intended for a slightly different model can lead to non-functional components (Wi-Fi, camera), network issues, or instability. Does it spike, drop, or become erratic? This is a strong indicator of a flexing problem, but carries high risk. The primary risk of jumpering a fuse is that you are removing a safety feature. Thorough analysis of smartphone touchscreen dead zones empowers technicians and DIY repair enthusiasts to accurately pinpoint the problem, avoid unnecessary repairs, and confidently proceed with the correct solution, primarily involving the replacement of the entire display assembly.2. Be sparing with the adhesive; too much can seep into the phone's interior or create a messy bond. Apply a thin, even layer of no-clean liquid flux to the cleaned pads on the motherboard. Battery First: The battery is typically the first component to be removed in a modular phone, which immediately de-energizes the device, preventing accidental shorts. Use a Dremel with a very fine grinding or cutting wheel to carefully cut a new slot into the stripped screw head. Physical Damage: The external button caps are missing, broken, or the underlying switch mechanism is visibly damaged. Protective Gear: Safety glasses and cut-resistant gloves are highly recommended due to glass shards. Accidental damage to these cables is often irreparable without specialized equipment and can necessitate an expensive screen replacement. These drivers are often generic but sometimes device-specific, so ensure you download the correct ones. Manufacturing Defects: Rarely, the OIS module might fail prematurely due to a defect. While it offers a glimmer of hope for irreplaceable data, the pervasive use of hardware-level encryption in modern devices significantly reduces the chances of success, making it a complex ethical and technical challenge for repairers.8. Phone Case or Screen Protector: An improperly designed or poorly fitted case or screen protector might inadvertently cover this essential port, preventing the sensor from reading external pressure. If the signal improves, it indicates environmental interference (buildings, walls). The Baseband processor, often referred to as the modem IC, is one of the most vital integrated circuits on a smartphone's logic board.

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