[SOLVED] I'm looking for Blu G51S repair guide or schematics (free) - Phones & Tablets Forum

Hi,

I'm hoping you can help me out with my Blu G51S. 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.

@Dominik

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 Blu G51S 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/how-to-download-xposed-framework-for-moto-g-running-cm14-1.3523060/
Take a look at comment #1676
Also, this : https://xdaforums.com/t/modem-flashable-mk3-sprint-modem.2538978/.
You can also check this video starting from minute 7:

The Blu G51S 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 Blu G51S 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 Blu G51S 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 Blu G51S 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/solved-duplicate-items-in-settings.3789089/

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

If the frame is bent or cracked, it can deform or damage the integrated antenna, impairing its performance. The issue can manifest in various ways: you might hear static or muffled voices, the person on the other end might not be able to hear you, your calls might drop frequently, or you might experience echoes. This usually involves removing a small metal bracket securing the connector, then gently prying the FPC connector straight up. This is crucial for True Tone to function with a non-original display. Governor and I/O Scheduler Tuning: Experiment with different CPU governors and I/O schedulers if the custom kernel offers them. This is crucial for high-speed data lines (e.g., MIPI DSI for display), clock signals, or communication buses (I2C, SPI) to check for correct frequency, amplitude, and timing. Internal Lens Elements: Look through the lens barrel from both the front and back. The camera is arguably one of the most emphasized features in modern smartphones, with manufacturers constantly pushing boundaries in image quality, low-light performance, and computational photography. Repair: Once the internal trace is exposed, the repair typically involves bridging the break with solder or a micro-jumper wire, similar to external trace repair, but within a much smaller, excavated cavity. Ensure no screws are in the wrong place, potentially shorting something. Inspect the SIM Card: Examine the SIM card itself for any physical damage. Inspect Connectors: Ensure the flex cables are securely seated in their sockets on the logic board. This creates a fully functional antenna directly on the device's structural elements. Take the new replacement front glass (which often has the digitizer already integrated). Disassembly: Carefully disassemble the smartphone, following a reliable guide for your model. The most common indication is blurry images, regardless of lighting conditions or subject distance. Button Cap Replacement: If only the external cap is damaged (rarely the only issue). Initial Testing: Before full reassembly, connect the logic board to a battery, display, and charging port. Obtain a Replacement Screen: Source a high-quality replacement screen assembly specific to your smartphone model. Position the motherboard on the preheater and set it to a temperature around 100-120°C. Replacing a smartphone front-facing camera is a precise repair that requires patience and careful handling of delicate components. ADB (if USB debugging enabled previously): If USB debugging was already enabled and authorized, connecting to a PC might allow you to use ADB commands to pull data. No Charging: The phone doesn't detect the charger at all, even with known good cables and chargers. This means you cannot simply swap a baseband chip from one iPhone to another, even if they are the same model. Reflow Oven: Designed for automated, controlled heating of an entire PCB or a specific region. If these preliminary checks confirm a hardware issue related to cellular connectivity and the IMEI/Baseband version is compromised, suspicion falls heavily on the Network IC. A swollen smartphone battery is not just a mere inconvenience; it's a critical safety hazard that demands immediate attention. Gently work it around the perimeter of the phone, slowly separating the back cover/screen from the frame. In conclusion, refurbishing the housing of a vintage or older smartphone is a detailed, multi-faceted process that goes far beyond a simple repair. If visual inspection reveals a damaged port, or if cleaning doesn't help, the entire charging port assembly (often on a flex cable or daughterboard) needs replacement.

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