[SOLVED] I'm looking for Celkon AR40 repair guide or schematics (free) - Phones & Tablets Forum

Hi,

I'm hoping you can help me out with my Celkon AR40. 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.

@Jéssica

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 Celkon AR40 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/533559/I+need+a+Screwdriver+set+to+take+this+motherboard+out+do+you+have+one
Take a look at comment #1253
Also, this : https://www.ifixit.com/Guide/How+to+Refinish+a+Scratched+Wood+Table/147514.
You can also check this video starting from minute 5:

The Celkon AR40 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 Celkon AR40 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 Celkon AR40 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 Celkon AR40 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/709607/Press+power+button+multiple+times+to+on

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

Adhesive Issues: If the adhesive used to seal the screen or back cover is not fully cured, applied unevenly, or missing in areas, it can create points of weakness where the panel can vibrate. Around the perimeter of the display assembly, bonding it to the phone's mid-frame. Diagnostic Tools (if available): Some phone manufacturers include hidden diagnostic menus (e.g., `#0#` for Samsung devices). Ensure its pins are clean and tinned (have a thin layer of solder on them). Quality Components/Repairs: When replacing components, ensure proper soldering techniques are used with quality solder. Near Field Communication (NFC) has become an indispensable feature in modern smartphones, enabling convenient functionalities like contactless payments (e.g., Apple Pay, Google Pay), quick pairing with Bluetooth accessories, and reading NFC tags for various applications. Aftermarket: Less smooth, often lacks effective oleophobic coating (fingerprints accumulate quickly), feels cheaper, more prone to scratches and cracking. If your phone isn't detected, re-check drivers, cable, and ensure the phone is in the correct flashing mode. Remove SIM Card Tray and Case: Clear the device of any external accessories. Inductor: A key component of the boost converter, storing energy magnetically and releasing it to step up the voltage. A malfunctioning autofocus system can render a powerful camera virtually useless, resulting in consistently blurry photos and a frustrating user experience. A damaged port can cause poor contact, increased resistance, and heat generation. Software Glitch: Less common for a brand new part, but a factory reset can sometimes help rule it out. Ensure they are properly sealed to prevent contamination or evaporation. Before even considering a physical antenna break, always rule out common software and pairing problems: Set up automatic backups to a cloud service (iCloud, Google Drive) or regularly back up to a computer. Mechanical Wear and Tear: Over thousands of presses, the tiny internal switch on the flex cable can degrade and lose its responsiveness. Electromagnetic Interference (EMI) is a persistent challenge in compact electronic devices like smartphones. C-Items: Low-value, slow-moving (e.g., specific screws, obscure flex cables). Backlight Inductor: Can go open or have internal shorting, causing inefficiency or complete failure. Environmental Obstructions: Thick walls, basements, high-rise buildings, mountains, or even weather conditions can block or attenuate cellular signals. While the repair itself might not directly interact with your phone's storage, any unforeseen issue during disassembly or reassembly could lead to data loss. Always follow reputable guides when flashing firmware, ensure stable power and connections, and use correct files for your device. If the new SIM works, it confirms your original SIM card is faulty (despite working in another phone, perhaps it's an intermittent issue, or sensitive to specific reader tolerances). Use a heat gun or hair dryer on a low-to-medium setting to gently warm the edges of the cracked back panel for 30-60 seconds. Network registration failures: Error messages indicating that one or both SIMs cannot connect to their respective networks. Factory Reset (Last Resort): If all software troubleshooting fails, a factory reset (which erases all data, refer to Topic 7) can rule out deep-seated software corruption. Thermal Imaging (Optional but helpful): Sometimes a damaged ground plane can indirectly cause other components to overheat if their heat dissipation path is compromised. It typically sits behind a small translucent window on the phone's front bezel. Reseat: Carefully disconnect and then firmly re-seat both display and digitizer flex cables.

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