[SOLVED] I'm looking for HTC One M8x LTE-A repair guide or schematics (free) - Phones & Tablets Forum

Hi,

I'm hoping you can help me out with my HTC One M8x LTE-A. 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.

@Lorraine

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 HTC One M8x LTE-A 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/firmware-kk-beta-international.2766713/
Take a look at comment #520
Also, this : https://www.ifixit.com/Answers/View/435704/Why+does+my+phone+always+die+and+restart+at+high+percentages.
You can also check this video starting from minute 3:

The HTC One M8x LTE-A 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 HTC One M8x LTE-A 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 HTC One M8x LTE-A 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 HTC One M8x LTE-A 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/miui-multilanguage.1920786/

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

When you navigate to your phone's Wi-Fi settings, you might find that the Wi-Fi toggle is greyed out and cannot be activated, or it might constantly switch itself off. Restart the Smartphone: A simple reboot can often resolve software glitches that might be making the phone misinterpret headphone insertion or blocking audio output. It opens up a world of customization but also introduces security risks and often voids the manufacturer's warranty. A short circuit on a power rail is a common cause of a dead device, and TPs help locate which rail is shorted and where the fault might lie. Router Settings: Check for any enabled Quality of Service (QoS) settings, MAC filtering, or parental controls that might be inadvertently blocking or throttling your phone. Inspect the Cable Connector: Look closely at the metal tip of your charging cable. This is a common cause of "searching for service" or poor Wi-Fi range. Frequent Disassembly/Reassembly: Repeated threading and unthreading can wear out plastic threads over time. Research the Method: Search for known unlock methods for that specific device. Lifted Pads: Applying too much force when lifting the old IC or cleaning can damage the board pads. Check SIM Reader Assembly (if modular): Some phones have a modular SIM reader that connects via a flex cable or a board-to-board connector. Known Good Camera Module: The most reliable hardware diagnostic is to replace the suspect camera module (including its attached flex cable) with a known good, working module. By paying close attention to visible gaps, creaking sounds, and abnormal flexibility, users can detect issues early. Systematic Approach: Always start with the simplest checks (network, software) before moving to complex hardware diagnostics. This layered design allows for incredibly dense component packing but makes internal trace damage particularly difficult to diagnose and repair. `Apply update from ADB`: Allows flashing updates or custom ROMs via Android Debug Bridge. However, keep in mind that a dry external LDI does not guarantee the absence of internal moisture damage, as liquid can sometimes seep in through other crevices without activating the readily visible indicators. Battery Discharge (Partially): If possible, discharge the battery to below 25% to reduce the risk of thermal events if the battery is accidentally punctured. The miniaturization of components on smartphone logic boards has reached extraordinary levels, with surface-mount devices (SMDs) often measuring fractions of a millimeter. Many heat guns have adjustable temperature settings; always start with the lowest effective setting. Fine-Tip Soldering Iron: A high-quality iron with a very fine tip (e.g., chisel or needle point) for intricate soldering work. Visible Cracks or Breaks: Direct impact damage can crack or shatter sections of the frame. Intermediate Connections: The speaker's ground might not connect directly to the main logic board ground. It requires not only advanced micro-soldering skills but also a systematic diagnostic approach and a deep understanding of smartphone sensor circuitry. If the power supply immediately shuts down (goes into constant current mode) and you don't detect a hot spot: This indicates an extremely low resistance short (almost direct short) drawing a lot of current very quickly. This requires advanced micro-soldering skills and often schematics/boardview. This degradation is not uniform; different colored sub-pixels (red, green, blue) degrade at different rates, with blue typically degrading fastest, followed by red, and then green. General-purpose oils can attract more dust or, worse, seep into the display layers, causing permanent damage. Purpose: Specialized tools made from static-dissipative or conductive materials. The components and pads are often measured in fractions of a millimeter.

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