[SOLVED] I'm looking for MAXCOM Comfort MM445 repair guide or schematics (free) - Phones & Tablets Forum

Hi,

I'm hoping you can help me out with my MAXCOM Comfort MM445. 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.

@Vinicius

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 MAXCOM Comfort MM445 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/xperia-go-mod-statusbar-for-sde.1913032/
Take a look at comment #1011
Also, this : https://www.ifixit.com/Answers/View/352034/I+can't+turn+my+Nikon+on.
You can also check this video starting from minute 2:

The MAXCOM Comfort MM445 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 MAXCOM Comfort MM445 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 MAXCOM Comfort MM445 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 MAXCOM Comfort MM445 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/cant-access-to-bootloader.689768/

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

Wireless charging has become an indispensable feature for many smartphone users, offering convenience and reducing wear on physical charging ports. Using the suction cup on the display (if applicable) and plastic opening tools, gently work your way around the perimeter of the screen, slowly separating it from the frame. Solder Jumper: Carefully solder the tinned end of the jumper wire to the exposed and tinned trace on the logic board. Replacing the internal plastic vibration motor mount is a moderate-difficulty repair due to the extent of disassembly required. The core of the dilemma lies in the vast amount of sensitive data stored on a smartphone: personal photos and videos, private messages, financial apps, health data, browsing history, and more. Without them, diagnosing complex power issues is significantly harder, if not impossible. Battery Health: A severely degraded battery can sometimes cause heat issues, although this usually manifests as rapid drain or swelling rather than direct thermal throttling of the SoC. Method: To check for burn-in, display a full-screen pure gray image (around 50% gray is often best). Lifting: Once the solder melts (you might see a slight sheen or movement), carefully lift the shield using tweezers or a vacuum desoldering tool. Once the back cover, battery, and potentially the display assembly are removed, the hinge mechanism becomes accessible. Re-partitioning and Flashing (Advanced): In very rare and severe cases, where the partition table itself is corrupted (often due to hardware failure or extreme mishandling), it might be necessary to re-partition the internal storage before flashing firmware. If reseating the flex cables and cleaning the contacts doesn't resolve the lines, the display panel itself is highly likely to be damaged internally. If on Mid-Frame: On some Android devices, the flex might be secured to the mid-frame itself, connecting to the logic board with its own connector. Antenna Contact Points: Some antennas rely on spring contacts or pogo pins directly on the logic board or frame. Brownish/Black Discoloration: This can indicate severe oxidation, burning (due to short circuits caused by corrosion), or carbonization from electrical arcing. Audio Processing Bugs: Software can sometimes incorrectly process or filter audio during video recording. Purpose: To quickly determine if there's a continuous electrical path between two points. The accelerometer's Z-axis reading should be close to 9.81 m/s² (gravity), and X and Y should be near 0. Use the physical volume buttons during video playback, or go to `Settings > Sound & vibration > Volume` and adjust the "Media" slider. Component Identification and Orientation: Every component has a specific function and orientation. Muffled or Distorted Sound: Audio from the affected speaker sounds unclear, dull, "underwater," or scratchy, even at high volumes. Torn traces: The microscopic copper pathways (traces) leading to the pads can be torn or scratched, effectively breaking the circuit. A consistent, uncorrectable color inaccuracy might be a permanent hardware characteristic of the panel. When using third-party apps, it's important to remember that their "health" estimations are often based on observed behavior and algorithms, not direct access to the battery's internal controller (which usually requires root access on Android). Recent SIM Swap/Upgrade: If you've recently upgraded your phone or performed a SIM swap, the new SIM might not be fully provisioned yet, or the old one might have been deactivated prematurely. Step 2: Thoroughly Remove All Old Adhesive Residue (THE MOST IMPORTANT STEP) A simple swap will result in the phone not booting or failing security checks unless the new chip is "programmed" with specific device identifiers from the original phone. Battery: If reusing the old battery, apply new adhesive to secure it firmly in the new housing. Once you've identified a shorted power rail using the multimeter, the next crucial step is pinpointing the exact location. Using your fine-tipped soldering iron, carefully apply a very small amount of fresh solder to "tin" these exposed copper points.

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