[SOLVED] I'm looking for HTC Desire 650 LTE repair guide or schematics (free) - Phones & Tablets Forum

Hi,

I'm hoping you can help me out with my HTC Desire 650 LTE. 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.

@Joaquin

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 Desire 650 LTE 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/discontinued-minimalism-google-play-3-10-10-market-only-gapps.1918484/
Take a look at comment #1348
Also, this : https://www.ifixit.com/Answers/View/473593/Faulty+display+after+replacing+HDD.
You can also check this video starting from minute 10:

The HTC Desire 650 LTE 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 Desire 650 LTE 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 Desire 650 LTE 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 Desire 650 LTE 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-is-the-exynos-galaxy-siv.2192403/

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

For Android: In Recovery Mode (as above), select "Wipe data/factory reset." Confirm the action. Replacing the Dedicated Image Signal Processor (ISP) in a Camera-Focused Smartphone Bluetooth operates on the 2.4 GHz radio frequency band, similar to Wi-Fi. If the phone does NOT respond: The problem is on the logic board, either the FPC connector itself, the traces leading to the PMIC, the PMIC, or surrounding components. Backup Data: Always back up all user data before flashing, as many processes will erase it. Accurate Diagnosis: To pinpoint the root cause of a malfunction (e.g., if the phone isn't charging, identifying whether the issue is with the PMIC, charging IC, or a simple capacitor). Wi-Fi Connectivity Issues: Difficulty connecting to Wi-Fi networks, frequent disconnections, very slow Wi-Fi speeds, or a significantly reduced range. Do not pull it by the cards themselves, as they might detach and fall. Commonly, the NFC antenna is located on the rear housing, adhered to the back of the battery, or integrated into a larger flex cable near the camera module, loudspeaker, or wireless charging coil, typically in the upper or lower part of the phone's back. It’s a process of gradually refining the damaged area, often involving sanding, polishing, and sometimes even filling or touch-up painting. Reinstall apps from the Google Play Store or Apple App Store, being mindful of permissions. The problem often develops gradually, as dust and debris accumulate over weeks or months, making it easy to dismiss initially as a poor network connection or a caller's microphone issue. The intricate world of smartphone repair demands a blend of precision, knowledge, and the right tools. Investing in a high-quality replacement (OEM, refurbished OEM, or premium aftermarket) significantly increases the chance of matching original volume output. If the phone is still functional enough, system logs (Logcat for Android) might show repeated thermal warnings, critical temperature alerts, or shutdowns triggered by over-temperature conditions. This is particularly challenging due to the thinness of the traces and the flexible nature of the material. If integrated with the power button, the power button becomes unresponsive or requires excessive force. Burnt Components: Components that have overheated due to excessive current draw or short circuits may appear discolored, swollen, or have visible burn marks. Anti-Static Precautions: ESD mat and wrist strap to protect sensitive electronics. The NAND flash memory Integrated Circuit (IC) is the solid-state "hard drive" of a smartphone. Screen Protectors with Lens Protection: Some screen protectors include a cutout or an additional layer of glass over the camera lens. Before diving into smartphone specifics, let's review the core functions: It's a high-reward repair when successful, restoring full functionality to an otherwise unusable device. A moderate humidity level, typically between 30% and 50%, is recommended. Use third-party apps like CPU-Z, AccuBattery, or similar system monitors. If everything works perfectly, power off the phone, disconnect the battery, and then disconnect the new display flex cables. This distinction is key to understanding why charging might succeed in one state but fail in another. These issues highlight the convergence of hardware and software in modern devices, where a physical repair is often only the first step in restoring full functionality. Power Off: Always power down your phone completely before starting any repair. Bluetooth Codecs: If using Bluetooth, check which codec is being used (e.g., AAC, SBC, aptX, LDAC).

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