[SOLVED] I'm looking for LeTV X621 Le 2 repair guide or schematics (free) - Phones & Tablets Forum

Hi,

I'm hoping you can help me out with my LeTV X621 Le 2. 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.

@Grzegorz

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 LeTV X621 Le 2 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/572656/How+to+work+with+iPhone+5s+glass+without+OCA+layer
Take a look at comment #1573
Also, this : https://www.ifixit.com/Answers/View/650580/My+MacBook+Pro+charging+light+stays+red.
You can also check this video starting from minute 1:

The LeTV X621 Le 2 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 LeTV X621 Le 2 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 LeTV X621 Le 2 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 LeTV X621 Le 2 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/Answers/View/69244/iPad+1+Droped+into+water+and+breakdown+the+connect+lines!

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

Remember: patience, gentle handling, and non-metallic tools are your best friends. Damaged Battery: An aging, physically damaged, swollen, or internally shorted battery is a common culprit. What should be a simple step in disassembly can quickly become a monumental roadblock, threatening to turn a routine repair into a device-bricking nightmare. While some issues might point to complex internal damage, many common audio problems can be diagnosed and fixed with basic troubleshooting steps. Excessive, localized heat can damage the battery, wireless charging coil, or other components. Before discarding the old screen, carefully inspect it for any components that need to be transferred to the new screen. Re-inspect: Carefully check the installed IC for alignment, cold joints, or shorts. Magnifying Glass/Microscope: For inspecting tiny connectors and components. On some phones, particularly older models, the plastic bezel might be a distinct, separate part that clips onto the phone's main frame. If your phone's battery percentage increases slightly, then drops, then increases again, all while unplugged, it could be a sign of ghost charging. Restart your phone into Safe Mode (specific steps vary by device, often involving holding the volume down button during boot). A failed LED array can manifest in several ways: a completely black screen with the phone still on, a very dim display, flickering backlight, or uneven illumination (e.g., bright spots and dark patches). Purpose: To pinpoint a component that is shorted to ground, which often heats up when power is applied. Headband Magnifier: Allows for hands-free magnification, which is incredibly useful for intricate work. These can easily scratch, bend, or short-circuit delicate internal pins and components, leading to irreversible damage. `dumpsys` can also provide `last_kmsg` (last kernel messages) after a crash. Once aligned, apply heat with the hot air station, using similar settings as for removal. Position New PMIC: Carefully place the reballed (or pre-balled) new PMIC onto the pads on the motherboard. Final Reassembly: If the new display works flawlessly, power off, disconnect the battery, apply new adhesive strips to the phone's frame, and carefully re-seat the display. High, Unstable/Pulsing Current: Could be a short or a component repeatedly activating and deactivating OCP. If the antenna is part of a flex cable (e.g., Wi-Fi/Bluetooth flex), disconnect it. Be extremely cautious not to pry too deeply, as internal flex cables (fingerprint sensor, wireless charging coil) are often attached to the back cover. If your device has a water resistance rating, understand that even with new adhesive, it might not be restored to its factory specifications unless done in a controlled environment with specific tools to test and certify the seal. Hot Air Rework Station: Crucial for desoldering the old port and sometimes for initial placement of the new one. These imperfections, no matter how small, can create microscopic gaps that a new gasket cannot fully bridge, leading to potential leak paths. This prevents accidental power to components and reduces the risk of short circuits. Clean Area: Once the old flex cable is removed, gently clean any old adhesive residue or debris from the mounting area using a cotton swab lightly dampened with isopropyl alcohol. Precision Screwdriver Set: You might need small Phillips (PH00/PH000) if internal components need to be moved, or a fingerprint sensor on the back cover needs to be transferred. Reference Guide: Obtain a disassembly guide or service manual for your exact phone model. Lines that Appear and Disappear: Might be intermittent, especially with movement or temperature changes, often indicating a loose connection.

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