[SOLVED] I'm looking for Samsung A687 Strive repair guide or schematics (free) - Phones & Tablets Forum

Hi,

I'm hoping you can help me out with my Samsung A687 Strive. 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.

@Jake

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 A687 Strive 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/571659/Unable+to+Activate+Shutdown+message+(BB_CPU)
Take a look at comment #230
Also, this : https://xdaforums.com/t/solved-htc-one-usb-not-recognizing-after-downgrade-hboot.2661271/.
You can also check this video starting from minute 10:

The Samsung A687 Strive 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 A687 Strive 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 A687 Strive 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 A687 Strive 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/update-online-petition-to-att-to-unlock-bootloaders.2809343/

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

NFC Malfunctions: Contactless payments or tag reading fails intermittently. After securely connecting the display and the battery, power on the device to perform a basic functionality test (display on, touch response, no flickering) before applying permanent adhesive or closing the device. Inspect and replace door seals/gaskets as needed to maintain an airtight seal. Software Update: Ensure the OS is up to date, as updates can contain modem firmware fixes. Sites like iFixit.com and numerous YouTube channels offer excellent step-by-step instructions. Continuity from Logic Board to Speaker Contacts: With the logic board accessible and the speaker removed, you can use a multimeter to check for continuity from the relevant pads on the logic board (where the speaker connects) back to the audio IC. Technicians must exercise extreme caution, utilize preheating plates, and apply precise temperature profiles with their rework stations. Always start with the simplest checks and progressively move to more complex diagnostics to minimize unnecessary component replacement or further damage. Troubleshooting microphone problems after a screen replacement requires patience, methodical inspection, and attention to the fine details of flex cable connections and routing. Remove these carefully if they are needed for the new flex cable or if you need to clean behind them. Filter Coils, Diodes, Capacitors: Associated passive components in the backlight circuit. The mount will be the plastic piece immediately surrounding or cradling the motor. Apply Flux: Apply fresh, liberal amounts of liquid flux to the cleaned pads on the logic board where the new port will sit. Smell Test (Cautionary): In some cases, a faint, acrid "burnt electronics" smell can be detected from a PCB that has experienced severe overheating. Plastic Spudgers and Precision Screwdrivers: For initial phone disassembly. Replacing a smartphone ambient light sensor is a manageable repair that requires patience, attention to detail, and a clean environment. Carefully align the new screen with the frame and gently press it down around the perimeter to engage the adhesive and any clips. Reboot: After the script finishes, your phone will reboot into the freshly installed stock Android. High-quality precision tweezers are essential for manipulating tiny components. Carefully align the new connector precisely over the clean solder pads on the logic board. Known Good Charging Port Assembly: Ensure the charging port and its flex cable are functional. Heat Generation: Excessive heat during charging or discharge is a major red flag. Plastic Pry Tools (Spudgers/Guitar Picks): Essential for safely separating components without scratching or damaging the plastic. If present, carefully disconnect them using a plastic spudger and tweezers. Connectors: Examine both ends of the cable for bent pins, corrosion, dirt, or debris. Persistence: Does the ghosting disappear quickly, or does it linger for several minutes or longer? Solder Paste and BGA Reballing Stencils (specific to the ICs being transferred). Age and Wear: Over many years, the adhesive can naturally degrade due to environmental exposure, thermal cycles, and general wear and tear. No Mobile Data: The phone cannot connect to cellular data, relying solely on Wi-Fi. If you experience eye strain, fatigue, headaches, or a general sense of discomfort after prolonged use of an OLED smartphone, especially in low-light conditions or at lower brightness settings, it's a strong sign that you might be sensitive to its PWM flicker.

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