[SOLVED] I'm looking for GETEK GK390 repair guide or schematics (free) - Phones & Tablets Forum

Hi,

I'm hoping you can help me out with my GETEK GK390. 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.

@Billy

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 GETEK GK390 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://www.ifixit.com/Answers/View/781504/Can+I+replace+the+headphone+jack+in+my+mid-2012+MBP
Take a look at comment #544
Also, this : https://xdaforums.com/t/wrist-charger.3118568/.
You can also check this video starting from minute 1:

The GETEK GK390 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 GETEK GK390 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 GETEK GK390 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 GETEK GK390 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/695334/Hi+I+got+a+cinema+display+that+was+broken+the+PSU+and+I+fix+it

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

A technician has specialized tools for cleaning, diagnosing internal damage, and performing repairs that require opening the phone. With under-display optical sensors, the sensor is typically located directly beneath the screen's active area. While pulling up gently on the suction cup, insert a thin prying tool (e.g., guitar pick, thin plastic card) into the gap created. This includes media volume, ringtone volume, alarm volume, and in-call volume. Start by holding the phone flat and moving it in a horizontal figure-eight pattern. If all other software troubleshooting fails, a factory reset will erase all user data and settings, restoring the phone to its original state. Re-evaluate Custom ROMs: If a custom ROM is causing issues, try a different, more stable version, or revert to stock firmware. The core of the repair lies in trace repair and pad reconstruction using microsoldering. Updates: Did stuttering begin after a recent software update? Sometimes, updates can introduce bugs or reduce optimization. Gentle Lift: Once the solder reflows, the connector will visibly "float" on the pads. The LED array itself is a small strip or cluster of tiny light-emitting diodes, often mounted on a flexible circuit board or directly on the display panel's flex cable. Understanding the signs and causes of motherboard flexing is crucial for accurately diagnosing persistent, intermittent phone malfunctions and determining whether a repair is feasible or if a replacement is the more practical solution.10. You will need a new display bracket specific to your smartphone model. However, if the module isn't even detected by the system, it's more likely a digital communication fault or a power supply issue to the module itself. ESD Protection: Use an anti-static mat and wrist strap to protect sensitive electronic components from static discharge. It is always recommended to seek out a professional repair service with proven micro-soldering expertise for such intricate tasks. Plastic Pry Tools (Spudgers) and Guitar Picks: Essential for safely separating components, disconnecting flex cables, and removing adhesive. If the reading is very high (over 100 ohms, or "OL" for open circuit), the coil is broken. Reset App Preferences: This step resets all default apps, disabled apps, app permissions, and background data restrictions without deleting any user data. Clean Corroded Contacts: Use isopropyl alcohol and a fine brush to meticulously clean any corrosion found on the logic board contacts or flex cable connectors. Replacing internal plastic shielding is a meticulous but essential repair that restores the smartphone's designed resilience and functionality. Dirt, lint, and other debris can accumulate around the button’s edges, obstructing its movement or preventing it from seating correctly. This helps verify if the IC is receiving proper power and if its data lines are intact. Apply Flux: Liberally apply high-quality liquid or gel flux around all pins and anchor points of the charging port connector. Diagnosis: If the flickering is only present at low brightness and disappears when brightness is increased, it's likely PWM. Avoid Heavy Usage While Charging: Charging generates heat, and heavy usage (like gaming or streaming) also generates heat. Crucially, check for any shorts on the line where the fuse blew before reconnecting the battery. If the RAM corruption symptoms persist under these conditions, it provides strong evidence of a hardware RAM fault. Replacement Wi-Fi Antenna: Ensure it's the correct and compatible part for your specific phone model. Front display removal: Use a suction cup and opening picks after heating the display edges.

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