[SOLVED] I'm looking for LG Optimus Pro C660 repair guide or schematics (free) - Phones & Tablets Forum

Hi,

I'm hoping you can help me out with my LG Optimus Pro C660. 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.

@Bilal

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 LG Optimus Pro C660 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/893803/What+the+heck+happened
Take a look at comment #668
Also, this : https://www.ifixit.com/Guide/CR-10+V2-V3+all+metal+hotend/146684.
You can also check this video starting from minute 10:

The LG Optimus Pro C660 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 LG Optimus Pro C660 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 LG Optimus Pro C660 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 LG Optimus Pro C660 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/q-using-nexus-5-with-tablet-data-only-sim-on-t-mobile.2739396/

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

Sometimes, the obstruction might not be immediately obvious, especially if the mesh is very fine or the debris is light-colored. Keys in a pocket, a gritty surface on a desk, or an accidental drop can leave unsightly marks. Warning: Excessive heat is dangerous and can lead to thermal runaway and fire. Power on your device once more and perform a final, comprehensive check of all functionalities to ensure the repair was completely successful. Apply carefully, allowing it to fully cure according to product instructions. Was it connected to a charger during a power outage or storm? Was it connected to a non-certified, cheap charger or a public charging station? Was it plugged into a computer when the computer experienced a fault? To circumvent this, smartphone manufacturers often integrate "antenna windows" or "antenna lines" , sections made of plastic, glass, or ceramic that are transparent to RF signals. In conclusion, the internal cleanliness and maintenance of a smartphone are not just cosmetic concerns but fundamental aspects of its functionality and longevity. Compare the reading to the expected battery voltage (typically around 3.7V to 4.2V for a fully charged lithium-ion battery). While persistent issues might point to rare hardware faults, the vast majority are resolvable through diligent software troubleshooting.The plastic mid-frame is a foundational component within a smartphone, serving as the skeletal structure to which nearly all other internal components are mounted. Very Low Resistance (near 0 ohms): Confirms a short circuit to ground on the main power rail. If you lack the necessary experience or equipment, it is always best to entrust such a repair to a professional micro-soldering technician. ESD Protection: Always work on an anti-static mat with a wrist strap to prevent electrostatic discharge damage to sensitive components. Interpretation: The PMIC initiated the power-on sequence, but immediately encountered a critical failure or short on a secondary rail that it tried to activate. Install Proper USB Drivers: Ensure your computer has the correct USB drivers for your specific phone model. Check Power Delivery: Ensure the charging port and PMIC (Power Management IC) are functional enough to deliver power to the CPU and eMMC/UFS. This step is critical for a successful connection and preventing shorts. Without it, the advanced biometrics of modern smartphones remain crippled. Hidden Connections: Ensure all flex cables and antenna cables are disconnected from the logic board. If light from the display is visibly leaking through the seam, it's a definitive sign of separation. Disconnect these carefully with a spudger before fully separating the part. "No Storage" or "Storage Full" Errors: The phone might report incorrect storage capacity or claim to be full even if there should be free space. Procedure: Carefully de-solder the old reader (often a small FPC or a soldered-down component), clean the pads, and then solder a new, OEM-quality reader in its place. Tools at Hand: Organize your tools (tweezers, spudgers, flux, soldering iron, desoldering braid) within easy reach, so you don't have to constantly move away from the eyepieces. Press and hold the Home button and the Side (or Top) button simultaneously for 10 seconds. Pay particular attention to delicate ZIF (Zero Insertion Force) connectors and ribbon cable sockets, ensuring they are not crushed. Gently heat the bent area of the metal frame with your heat gun for 30-60 seconds. Precision Screwdriver Set: Containing Pentalobe, Torx, and Phillips bits as required by your phone's fasteners. Essential for fixing soft bricks, updating, or downgrading Samsung devices. Prying Components: Attempting to pry off components that are still soldered to the board, rather than properly desoldering them, almost guarantees lifted or torn pads.

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