[SOLVED] I'm looking for TAMBO A1806 repair guide or schematics (free) - Phones & Tablets Forum

Hi,

I'm hoping you can help me out with my TAMBO A1806. 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.

@Hélène

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 TAMBO A1806 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/how-to-flash-chinese-rom.2351361/
Take a look at comment #402
Also, this : https://xdaforums.com/t/solved-asking-for-previous-password-after-wipe-wont-accept-google-credentials.4412375/.
You can also check this video starting from minute 6:

The TAMBO A1806 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 TAMBO A1806 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 TAMBO A1806 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 TAMBO A1806 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/psa-att-introduces-mobile-share-today.1849305/

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

Depending on the phone architecture, you might need to transfer one or more of these critical chips. This can happen due to failed updates, improper rooting/jailbreaking, or malware. Allow the solvent to soak for a few seconds, then rub or gently scrape. A faulty charging IC can overcharge or improperly charge the battery, triggering thermal runaway. If using solder wire, you can "tin" each pad lightly with fresh solder. Repairing this issue involves opening the phone, carefully removing the old cable, and installing a new one. Clean the motherboard thoroughly, especially around the PMIC, with IPA and a brush. While usually granted by default, sometimes they can be revoked or corrupted. If the issue persists, flashing the stock firmware can address corrupted system files that might be misinterpreting sensor data or managing thermal profiles incorrectly. I2C/SPI Communication Lines: Used for communication between the CPU and display/digitizer controller ICs for initialization and status. The Charging IC is a crucial component on the logic board, responsible for managing the flow of power from the charger to the battery and often the overall power distribution to other phone components during charging. If the problem persists after a factory reset, it's a strong indicator of a hardware fault. This IC rectifies the alternating current induced in the coil by the external charging pad, converts it to a stable DC voltage, and then feeds it into the main charging circuit, often directly to the PMIC, effectively bypassing the USB port for power input. Description: These highly specialized tools are primarily used by law enforcement, government agencies, and data recovery specialists. A preheater, while not strictly mandatory for every repair, is highly recommended as it helps prevent motherboard warping and reduces thermal stress on surrounding components. ESD Protection: Always use an ESD mat and wrist strap when working with internal phone components to prevent static discharge damage. Microphone/Speaker Issues: If the separation occurs near microphone or speaker grilles, it could affect audio quality or volume, as the acoustic chamber integrity is compromised. Precision screwdriver set (Phillips, Pentalobe, Torx, Tri-point, etc., specific to your phone model) Liquid Damage: Corrosion leading to open traces, short circuits, or damaged ICs/connectors. Remove Logic Board: After disconnecting all peripherals, carefully remove the entire logic board from the phone's frame. Research Specific Model: Look up specific tear-down guides or videos for your exact phone model. Prioritizing genuine parts not only ensures the longevity and proper functioning of the repaired device but also upholds the integrity of the repair industry.4. Beyond the financial loss of the device, the theft of a smartphone can lead to severe data breaches, identity theft, and significant reputational damage for the repair business. New Adhesive Strips (for reinstallation): For securing the new battery. Obstruction: Double-check that the external microphone hole and the mic on the flex cable are not obstructed. Fortunately, replacing a plastic back cover is one of the more straightforward and accessible DIY smartphone repairs, making it an excellent starting point for those new to phone repair. Power Instability: The main battery's output or a power rail on the motherboard might be unstable, leading to inconsistent power delivery. Software Bugs: A bug in the camera app or OS can cause inefficient resource allocation. Observing the battery usage graph in your phone's settings (`Settings > Battery > Battery Usage` or similar) can reveal erratic charging patterns. Reconnect Components: Reconnect all flex cables and components that attach to the logic board.

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