[SOLVED] I'm looking for Vivo Y300 GT repair guide or schematics (free) - Phones & Tablets Forum

Hi,

I'm hoping you can help me out with my Vivo Y300 GT. 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.

@Margaret

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 Vivo Y300 GT 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/rom-official-kitkat-4-4-2-p705-pac-man-4-4-beta1-0.2704650/
Take a look at comment #1361
Also, this : https://www.ifixit.com/Wiki/HP_Stream_11-r020nr_Troubleshooting.
You can also check this video starting from minute 1:

The Vivo Y300 GT 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 Vivo Y300 GT 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 Vivo Y300 GT 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 Vivo Y300 GT 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/need-warp-4g-n9510-drivers-for-pc.2712085/

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

Internal Coatings: Some internal components or the entire logic board may have a conformal coating for added protection. Phase 2: Functional and Internal Indicator Checks (Advanced User/Technician Assessment) Often, the secondary loudspeaker is located near the top of the phone, either under the earpiece speaker or as a separate module near the top edge. Liquid Damage: Corrosion on antenna contacts, flex cables, or the amplifier ICs can severely degrade signal. Screen Protectors with Lens Protection: Some screen protectors include a cutout or an additional layer of glass over the camera lens. To prevent overheating and performance throttling, manufacturers incorporate various cooling mechanisms, collectively forming the smartphone's internal cooling system. Systematic Scan: Inspect every accessible connector on the motherboard and all flex cables. Test in Safe Mode (Android Only): This disables all third-party applications. Signal layers carry electrical signals between components, while power and ground planes provide stable voltage and ground references. Set your multimeter to continuity mode (or resistance, typically 200 ohms range). Charring/Burn Marks: Blackened areas, indicating severe overheating or short circuits. Physical Security: The clips also help secure the metal shields to the PCB, preventing them from vibrating or coming loose, which could cause shorts or damage components. Symptoms of haptic response delays are primarily subjective but can be quite noticeable. Purpose: This technique re-melts the solder joints beneath the IC, often resolving issues caused by micro-fractures from drops or manufacturing defects. Moreover, the seals are often comprised of adhesive gaskets and rubber seals around openings like charging ports, SIM trays, buttons, and speakers. This issue can stem from a variety of sources, ranging from simple software glitches and incorrect settings to more serious hardware failures. Gently disconnect and then carefully, perfectly, and securely re-seat all relevant flex cable connectors (display, front camera, charging port, etc.). An equally critical aspect of the IC's function is its implementation of the Medium Access Control (MAC) layer. Regular wiping: Routinely wipe your phone with a microfiber cloth to prevent dust buildup. This might involve gentle scraping with a scalpel (cold or slightly warm) or using a fiberglass pen, followed by IPA cleaning. The inductor might not have been the sole problem; there could be other damaged components on the power rail (e.g., the PMIC itself, a shorted capacitor). Essential tools include precision screwdrivers (Phillips, Pentalobe/Torx), a plastic spudger, thin pry tools (e.g., guitar picks), a heat gun or hairdryer, isopropyl alcohol (90% or higher concentration), a lint-free microfiber cloth or cotton swabs, and possibly fine-tipped tweezers. Higher refresh rates place greater demands on the display driver IC and the display flex cable's integrity. Optimizing these settings isn't about magical fixes, but rather about identifying and controlling the biggest power drains and adopting habits that promote efficiency. Document Everything: Take photos at every step, especially of screw locations and component placements. Once the adhesive is softened, use a suction cup to create a small gap, then insert a thin opening pick and slowly work your way around the perimeter, prying the screen or back cover away from the frame. This provides an accurate distance measurement, aiding in rapid focus. Logcat (Advanced): For experienced users, connecting the phone to a computer via ADB (Android Debug Bridge) and pulling a logcat can be highly informative. Headphone Jack Replacement: If cleaning fails, and there's clear evidence of physical damage to the headphone jack (bent, broken, or corroded pins), or if the issue persists despite thorough cleaning and software troubleshooting, the headphone jack assembly itself likely needs to be replaced. Magnifying Glass or Microscope: For visual inspection of small components, solder joints, and traces.

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