[SOLVED] I'm looking for Motorola E390 repair guide or schematics (free) - Phones & Tablets Forum

Hi,

I'm hoping you can help me out with my Motorola E390. 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.

@Astrid

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 Motorola E390 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/gyro-sensor-issue.3410384/
Take a look at comment #924
Also, this : https://www.ifixit.com/Answers/View/446758/How+do+you+hook+up+Bluetooth+headphones+to+a+Samsung+smart+tv.
You can also check this video starting from minute 3:

The Motorola E390 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 Motorola E390 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 Motorola E390 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 Motorola E390 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/hot-galaxy-note-5-apps-and-mods-port-for-t-w-lollipop-5-1-1-updt-19-01-16.3296150/

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

While gently pulling up on the suction cup, use a plastic opening tool (like a thin guitar pick or a specialized opening tool) to carefully insert into the tiny gap between the screen and the frame, starting near the charging port. Inspect any small cavities, recesses, or speaker grilles around the frame's perimeter. Software Updates: Ensure your phone's operating system is fully updated. NAND Flash: The primary storage for the operating system, user data, and applications (gigabytes in size). Wireless data instability refers to a scenario where a smartphone struggles to maintain a consistent, high-quality connection to wireless networks. Perform a hard reset by holding the Power button (or Power + Volume Down, depending on your model) for 10-30 seconds until the phone powers off and attempts to restart. If the camera works correctly and focuses sharply, you can proceed with full reassembly. Try ports on the back of a desktop computer (which are usually directly connected to the motherboard) rather than front-panel ports or USB hubs. Heat: Use heat sparingly and carefully, especially around the battery or display components. Carefully disconnect the screen's flex cables from the logic board and set the old screen aside safely (or dispose of it if it's completely beyond repair). A single slip of the separation wire or too much force can easily crack the LCD/OLED, render the digitizer unresponsive, or create dead pixels, turning a potentially cheaper repair into a more expensive full assembly replacement. With patience and dedication, you can master this challenging repair and save numerous smartphones from an untimely demise.The Power Management IC (PMIC), often pronounced "P-MIC," is one of the most critical components on a smartphone's logic board. Smartphone displays are a marvel of modern engineering, providing us with vibrant visuals and crystal-clear text. Mechanical Durability: The secured jumper must be robust enough to withstand minor vibrations, impacts, and pressure from reassembly. Flux dramatically improves solder flow, reduces surface tension, and prevents oxidation, making it easier to achieve clean, strong joints. Kapton tape (for protecting sensitive components during heat application) It's adhesive on one side, and the other side is conductive (single-sided conductive adhesive is preferred, ensuring the adhesive side is non-conductive and the copper/aluminum side is conductive). Specialized eMMC/UFS Programmer: Examples include JC P13, WL, EasyJTAG, UFI Box, Medusa Pro, etc. The vibration motor in a smartphone is a small, often overlooked component, yet it provides crucial haptic feedback for notifications, calls, and screen touches. Understanding and analyzing thermal throttling helps you manage your phone's performance expectations and ensures its longevity.### 8. Soft Brush: Use a clean, dry, soft-bristled brush (like an old toothbrush) to gently sweep away surface dirt and lint from all speaker grilles (earpiece, loudspeaker) and microphone holes. The polarizer's role is to filter this light, allowing only light waves oscillating in a specific plane to pass through, thus creating the contrast and visibility necessary for a legible image. Each Wi-Fi/Bluetooth IC is assigned a unique 48-bit MAC address, a hardware identifier that allows it to be uniquely identified on a network. This method will completely wipe your device and install a fresh copy of Android. If attempted, use a warm (not hot) damp cloth over the area for a very short duration, ensuring no moisture enters the device. An ultrasonic cleaner uses high-frequency sound waves to create microscopic bubbles in a cleaning solution, which then implode, generating tiny jets that dislodge contaminants from every crevice of the board. When it fails, the symptoms can be varied and severe, making diagnosis challenging for the untrained eye. A clean surface is essential for the new adhesive to bond properly and maintain water resistance. When it malfunctions , producing blurry images, black screens, focus issues, or generating a "cannot connect to camera" error despite software troubleshooting , replacing the entire camera module becomes a necessary repair. Missing screws, especially conductive ones, can break critical ground connections.

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