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

Hi,

I'm hoping you can help me out with my Hmd Bold. 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.

@Amine

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 Hmd Bold 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/8mp-versus-6-5mp-widescreen.1621723/
Take a look at comment #1499
Also, this : https://xdaforums.com/t/rom-official-resurrectionremix-v6-1-0-android-8-1-0-19-07-2018-bi-weeklies.3819129/.
You can also check this video starting from minute 10:

The Hmd Bold 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 Hmd Bold 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 Hmd Bold 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 Hmd Bold 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/128964/memory+RAM+stuck+inside+at+the+bottom+slot

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

Stock recovery often has options for wiping data or applying updates from ADB/SD card, which can help fix OS corruption, but not necessarily bootloader issues. Improper Disassembly/Reassembly: Pinching, tearing, or bending the flex cable during repair. Clean Other Components: Use IPA and cotton swabs or a soft brush to clean any water-damaged flex cables, camera modules, speaker contacts, and other removed parts. Clean Pads: After removal, use solder wick and a soldering iron to clean the old solder from the pads on the mainboard. The Wi-Fi/Bluetooth IC communicates with the smartphone’s main system-on-chip (SoC) , the central brain of the device , through a high-speed digital interface, typically SPI (Serial Peripheral Interface), SDIO (Secure Digital Input/Output), or PCIe (Peripheral Component Interconnect Express). Heat softens the adhesive, making it easier to remove both the glue and the trapped glass. Precision Hobby Knife or Razor Blade: For trimming plastic (use with extreme caution). Ensure no glass shards or tiny pieces of debris remain, as these can cause pressure points or damage the new adhesive. Dispose of used cleaning solutions responsibly, according to local environmental regulations. Recent Repairs: Has the phone undergone any repairs, especially screen or battery replacements? If so, the Wi-Fi antenna's flex cable or connector might have been accidentally left loose or improperly reconnected during reassembly. It's usually situated at the top of the phone, adjacent to the earpiece speaker. Aftermarket (Standard / Mid-Grade): Generally acceptable quality for budget-conscious repairs, but may have minor differences in performance (e.g., slightly lower brightness, less vibrant colors). Heat Gun or Hot Air Station: To soften adhesive for screen or back cover removal. Internal Components: Many phones have components (like wireless charging coils, NFC antennas, camera flash modules, microphones) directly adhered to the back glass or positioned very close to its edges. Power Management IC (PMIC) Failure: The PMIC is a crucial chip that manages all power functions in the phone, including charging, battery regulation, and power distribution. Open the Google Play Store and check for updates for all your installed apps, especially Google apps and the Camera app. Liquid Damage: Even if external signs are minimal, internal liquid damage can cause shorts on the motherboard, particularly around the charging control components. The SIM card communicates with the baseband processor via several data lines (e.g., SIM_DATA, SIM_CLK, SIM_RST). Effective cooling allows the SoC to run at peak performance for longer. Once cured, this excess glue becomes extremely difficult to remove without damaging the phone. Locate the battery connector (usually covered by a small metal bracket held by tri-point or Phillips screws). While many factors contribute to battery depletion, an unusually rapid discharge that isn't attributable to heavy usage, constant screen-on time, or a dying battery could be caused by hardware components being kept active unnecessarily or drivers consuming excessive power due to a software bug. Display Driver IC: This highly specialized integrated circuit is responsible for controlling the individual pixels of the display. Video Guides: Always search for a specific video guide for your phone model. Define Support Boundaries: Clarify what kind of post-flash support, if any, will be provided. Motherboard: The primary RF transceiver and power amplifiers for cellular and Wi-Fi are usually tiny ICs directly on the main logic board. Systematically tap each number or letter, observing if the correct input is registered. Most modern SoCs also utilize Package-on-Package (PoP) technology, where the RAM (Random Access Memory) chip is stacked directly on top of the SoC, connected by even finer solder balls. Digitizer Layer: A grid of transparent electrodes embedded in or beneath the glass, which senses touch input. Apply new adhesive around the perimeter of the new housing where the screen sits.

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