[SOLVED] I'm looking for Yezz Andy A4 repair guide or schematics (free) - Phones & Tablets Forum

Hi,

I'm hoping you can help me out with my Yezz Andy A4. 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.

@Emiliano

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 Yezz Andy A4 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/649981/My+phone+is+stuck+on+boot+loop+after+clearing+cache.
Take a look at comment #1715
Also, this : https://www.ifixit.com/Answers/View/370631/Why+won't+my+tablet+let+me+sign+into+my+Google+account.
You can also check this video starting from minute 7:

The Yezz Andy A4 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 Yezz Andy A4 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 Yezz Andy A4 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 Yezz Andy A4 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/q-wifi-tether-windows-doesnt-see-it-mac-does-as-device.2241953/

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

Interference (Wi-Fi/Bluetooth): Other electronic devices (microwaves, cordless phones, even neighbors' Wi-Fi) can cause interference. A missing voltage, an incorrect voltage, or a short circuit on a power rail will invariably lead to problems. Do not force it or pull it completely off, as the display's flex cables are still connected. This guide will walk you through the best practices for safely and effectively cleaning dust from your smartphone's speakers and ports. Collect a very long dataset (ideally several hours, 2-4 minimum) of static angular velocity data. The phone should now detect the SIM card and attempt to register on the cellular network. Action: Briefly touch the tip of a fine-point soldering iron to the head of the screw for 5-10 seconds. Precision Screwdriver Set: Pentalobe, Phillips, Torx bits as required for your phone model. Install New Battery: Install a new, high-quality replacement battery using fresh adhesive. Brush Gently: Use a soft brush to gently scrub the pins and surrounding areas. Display assembly replacement is one of the most common and impactful repairs a technician or DIY enthusiast will undertake. Common causes include: a physically damaged or swollen battery, a loose or corroded battery connector, a faulty charging port module, a software bug causing miscommunication, or, more seriously, a damaged PMIC or battery ID circuit on the motherboard. Unlike a dead short or a completely failed component, a loose connection might only manifest under specific conditions , perhaps when the phone is flexed, dropped, or experiences a slight temperature change. Use Device Manager to check for unrecognized devices and update drivers manually. In rare cases, a component failure on a power line or data line leading to the SIM reader could also cause issues, requiring advanced board-level schematics and diagnostic skills. They attempt to bypass or brute-force encryption, which is beyond the scope and ethical boundaries of a typical repair shop. Addressing this issue promptly and effectively is paramount for both the longevity of your device and your personal safety. Heat Adhesive: Apply gentle, even heat to the edges of the back panel or display to soften the adhesive. If it's adhered to the rear glass or a plastic shield, you may need to apply a small amount of heat to soften the adhesive and then carefully pry it off with a plastic spudger or tweezers. While these components are marvels of engineering, they are also prone to damage from drops, water ingress, or improper handling during screen replacements, leading to the dreaded "Face ID Not Available" message. Incorrect Version/Region: The OS boots, but it's the wrong region or a significantly older version, leading to compatibility issues. Consult a reliable repair guide or teardown video specific to your device. Check the flex cables (display, charging port, button flexes, antenna cables) that will connect to the motherboard; ensure they are clean, free of kinks, and positioned so they won't be pinched or creased during the motherboard's placement. Electrical Insulation: Prevents shorts to adjacent traces or components. The abrasive in toothpaste is meant for enamel, not glass, so choose the least abrasive type. By understanding the fragility of these sophisticated lenses and committing to non-abrasive, proper cleaning techniques, you can ensure your smartphone camera continues to capture crisp, clear, and vibrant images for years to come. Once warm, carefully use a plastic spudger or thin plastic card to gently pry and peel the old module away from its adhering surface. Trace Repair: Repairing broken electrical pathways on the PCB, often due to physical damage or corrosion, using jumper wires and UV solder mask. Crucially: Use compressed air or a blower bulb to thoroughly blow away any dust, lint, or debris that might have entered the camera lens cavity. The alcohol will dissolve remaining adhesive residue, grease, and grime.

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