[SOLVED] I'm looking for RELAXX Z12 repair guide or schematics (free) - Phones & Tablets Forum

Hi,

I'm hoping you can help me out with my RELAXX Z12. 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.

@Kate

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 RELAXX Z12 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/tutorial-existenz-z-z2-z3-custom-header-image.3231802/
Take a look at comment #840
Also, this : https://xdaforums.com/t/mobile-data-not-working-on-international-s3.2409916/.
You can also check this video starting from minute 7:

The RELAXX Z12 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 RELAXX Z12 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 RELAXX Z12 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 RELAXX Z12 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/best-treble-rom-for-xiaomi-mix2s.3825627/

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

Samsung (newer): Press and hold Power button + Volume Down for about 10 seconds. Battery Disconnection: Once the back cover is off, immediately disconnect the battery to prevent accidental short circuits during the repair. Research Your Model: Display removal and flex cable locations vary significantly. Follow up with a small amount of 99% isopropyl alcohol on a cotton swab if there's residue, allowing it to fully dry before reconnecting. Another software diagnostic technique is booting the phone into Safe Mode (available on most Android devices). Unfortunately, software solutions are generally ineffective for these errors. Installation of New Connector: Apply a small amount of fresh flux to the cleaned motherboard pads. Be careful not to damage the earpiece speaker, front camera, or any other components that might be integrated with or adjacent to the flex. Pentalobe, Phillips, and/or Tri-point screwdrivers: Depending on your phone model. In conclusion, the careful and complete removal of oxidation from water-damaged smartphone connectors is a critical repair process. Lack of Updates: Unlike OEM firmware, custom ROMs rely on community support for security patches. This is highly risky and should only be attempted by experienced individuals, as springs are brittle. If the new display works perfectly, it confirms that your original display assembly (digitizer) is faulty and needs full replacement. By understanding the interaction between gold and solder and applying precise preparation methods, reliable and durable solder joints can be consistently achieved, ensuring the longevity of smartphone repairs.## 7. If the known good card also exhibits read issues, the problem is with your smartphone's SD card slot or its software/hardware. Remove the Faulty Headphone Jack Assembly: Once all screws and connectors are removed, carefully lift and remove the old flex cable assembly. They are linked to thyroid disruption, developmental problems, and neurological damage. This step cannot be stressed enough , residual dust or smudges will ruin your photos. It often goes through a few components (like a fuse Fxxx or a current sense resistor Rxxx) before reaching the main PMIC (Uxxx). Hardware Inspection: If the phone is opened, visually inspect the battery. Enable USB Debugging: Keep USB debugging enabled (if you understand the security implications) on Android, as it can be a lifesaver for data extraction from non-booting devices. This often appears as a greenish, whitish, or reddish discoloration on the metal surfaces, indicative of liquid exposure. Without pre-heating, applying intense, localized heat directly to a large component can cause significant thermal stress to the board and surrounding components. The primary tool for diagnosing stuck pixels is your smartphone itself, along with specific software applications or online tools designed for display testing. Water and Dust Resistance: Sealing a phone for ingress protection can inadvertently trap heat, making dissipation harder. Reconnect Battery: Reconnect the battery flex cable to the motherboard. Before diving into specific troubleshooting steps, it's crucial to define the scope of the problem. CPU not responding: The CPU might be dead or not receiving its first power/clock signals, preventing it from performing its initial handshake with the PMIC. Place the black probe on a known ground point on the logic board (e.g., a metal shield, a ground test pad, the negative battery terminal). Rapid Evaporation: Dries quickly, minimizing the risk of moisture entrapment and allowing for faster turnaround times.

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