[SOLVED] I'm looking for Doogee S40 Pro repair guide or schematics (free) - Phones & Tablets Forum

Hi,

I'm hoping you can help me out with my Doogee S40 Pro. 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.

@Manish

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 Doogee S40 Pro 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/who-here-disabled-tf3d.549505/
Take a look at comment #1082
Also, this : https://www.ifixit.com/Guide/Nokia+3395+Back+Case+Replacement/4044.
You can also check this video starting from minute 3:

The Doogee S40 Pro 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 Doogee S40 Pro 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 Doogee S40 Pro 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 Doogee S40 Pro 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/Audio+Technica+ATH-AD500+Right+Headphone+Cable+Replacement/12858

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

Fine Enamel-Coated Copper Wire (Jumper Wire): Extremely thin (e.g., 0.01mm-0.05mm, often found in old speaker coils or magnet wire). Organize Screws: Keep track of screws as they vary in size and length. Sometimes, the "System UI isn't responding" error is a momentary hiccup. They play a pivotal role in holding together the myriad of components, providing structural integrity, creating water and dust seals, and even assisting with thermal management. Check Temperature Readings: Some diagnostic apps can report internal battery and CPU temperatures. In the dynamic world of smartphone repair and customization, technicians are occasionally approached with requests to flash customized firmware (often referred to as custom ROMs or modified operating systems) onto a customer’s device. For example, `adb shell dumpsys battery` provides detailed battery stats, `adb shell dumpsys input` for touch/keypad, `adb shell dumpsys media.camera` for camera status. Impact Damage: A drop or blunt force impact, even without a visible crack, can damage the digitizer matrix underneath the glass. For persistent issues, a factory reset (Settings -> General -> Transfer or Reset iPhone -> Erase All Content and Settings) or restoring via iTunes/Finder is the most effective solution for iOS. Adjacent Component Damage: The heat from a hot air station can radiate outward, affecting nearby capacitors, resistors, and even other ICs that are not intended for removal. By monitoring the current draw from the power supply during different states (off, booting, idle, in use), a technician can identify abnormal current spikes or constant high draw that points to specific component failures. Even a tiny speck of dirt or dust can block the infrared emitter/receiver. Cleanliness: Ensure all contact points, flex cables, and sensor areas are impeccably clean. These gases build up inside the sealed battery casing, causing it to swell. Visual Inspection: Look for any missing, cracked, or corroded filters/switches. Replacing a dedicated DSP in a smartphone is undoubtedly one of the pinnacles of micro-soldering skill. Clean the Area: Thoroughly clean the area where the new antenna cover will sit. Pry Open: Use a suction cup and plastic prying tools to carefully separate the display or back panel from the frame. Look for visible dirt, lint, earwax, corrosion, or damage/absence of the mesh. While replacing the sensor IC is an advanced repair, a systematic diagnostic approach can quickly pinpoint the problem and guide the repairer to the correct solution, restoring full smart-case functionality to the device.10. Place the new flex cable assembly into position, ensuring it's properly aligned and secured with screws/adhesive. Faulty Replacement Part: Though unlikely for a new part, the replacement daughterboard itself could be faulty. They have specialized tools for cleaning and can assess if the port needs replacement or if there's damage to the motherboard. Initial Separation: Once adequately heated, attach a suction cup to a strong, intact part of the screen, ideally near the bottom edge. Disconnection: Ensure the flex cable connecting the ALS module to the logic board is securely seated. Suction Cup: To help lift the display assembly (if opening from the front). Always consult a specific teardown guide for your exact model (websites like iFixit.com are excellent resources). This often appears as a greenish, whitish, or reddish discoloration on the metal surfaces, indicative of liquid exposure. Plastic Pry Tools (Spudgers/Guitar Picks): Essential for safely disconnecting flex cables, prying up components, and separating panels without causing damage. Flex Cable Assembly: Due to their small size and close functional relationship, these sensors (and sometimes other components like the front camera or earpiece) are typically manufactured together on a delicate, flexible printed circuit board (FPC) that connects to the main logic board.

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