[SOLVED] I'm looking for AMGOO AM86 repair guide or schematics (free) - Phones & Tablets Forum

Hi,

I'm hoping you can help me out with my AMGOO AM86. 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.

@Akram

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 AMGOO AM86 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/q-major-help.2509385/
Take a look at comment #2
Also, this : https://www.ifixit.com/Answers/View/679708/Why+is+my+laptop+not+charging.
You can also check this video starting from minute 10:

The AMGOO AM86 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 AMGOO AM86 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 AMGOO AM86 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 AMGOO AM86 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/806193/Should+I+attempt+to+replace+my+logic+board

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

Screen Damage: The most common risk is cracking the screen due to uneven pressure or torsion. Hot Air Rework Station: For removing components that might be covering the damaged area. CPU/RAM communication issues: The CPU is alive but cannot properly communicate with RAM or NAND. Heat gun or iOpener: To soften adhesive holding the screen or back panel. As the solder melts, the IC will visibly "settle" or self-align into place. This controller triangulates the touch location and sends the data to the phone's CPU. Consistent Intermittent Charging: If the wiggle test fails repeatedly. Use the appropriate precision screwdriver (e.g., Tri-point for many iPhones) to remove these screws. Component Orientation: For SMD microphones, confirm the correct orientation (pin 1 marking, dot, or line) before soldering. Purpose: Thin, flexible plastic pieces used to gently pry apart adhesive-bonded components like screens or back covers. Incorrect Paste Type: Using conductive paste can short circuit components. Verification of Ownership: Any repair involving an IMEI should ideally begin with verifying the customer's legitimate ownership of the device. Their operation is simple yet profoundly effective: a thin wire or filament within the fuse is engineered to melt and break the circuit when the current flowing through it exceeds a predetermined safe limit. Connectors: Carefully connect the flex cable to its FPC connector on the logic board or other components. Consult the solder paste/ball manufacturer’s datasheet for recommended profiles. Using a plastic spudger, carefully pry up and disconnect the display and digitizer flex cables from their sockets on the motherboard. Initial Test (Before Full Reassembly): Temporarily power on the phone (without fully sealing it) and perform the microphone test (make a test call, use the voice recorder). Magnification (magnifying lamp or microscope for inspecting small connectors) Crucially, mask off all surrounding components meticulously with Kapton tape or other protective layers. However, the symptoms that lead a technician to open the phone might include chronic device overheating (even during light use), unexpected shutdowns, poor overall performance (throttling), battery drain, boot loops, or the failure of specific components (e.g., Wi-Fi module, charging IC) without any apparent external damage. Sensors/Earpiece Blocked: The adhesive might have covered a sensor or the earpiece mesh. Often, port replacement is the safest solution for significant intrusions. Boot into Safe Mode (Android): If the issue might be caused by a third-party app, boot into Safe Mode (disables third-party apps). Excessive Wobble: A loose fit indicates a worn or deformed outer shell, a damaged central tongue (USB-C), or worn internal retention clips. It's a journey into the deeper layers of your smartphone's software, and successful navigation requires careful planning, thorough research, and meticulous execution.4. Stencils come in two main types: "direct heat" stencils (where heat is applied directly through the stencil during reflow) and "indirect heat" stencils (used with reballing jigs, where the IC is removed from the jig for reflow). After cleaning a grille, replacing a speaker, or reconnecting a cable, partially reassemble the phone enough to test the speakerphone. For repair shops, offering this service demonstrates a high level of technical capability, but it should only be attempted when confident in the skills and with all necessary equipment. While less complex than micro-soldering, it still requires precision, patience, and careful handling of delicate components. Proceed with caution and only if you are comfortable with smartphone disassembly.

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