[SOLVED] I'm looking for CHEERS Sleek 12 repair guide or schematics (free) - Phones & Tablets Forum

Hi,

I'm hoping you can help me out with my CHEERS Sleek 12. 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.

@Tyler

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 CHEERS Sleek 12 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/incoming-call-i-can-not-see-my-name.3659758/
Take a look at comment #297
Also, this : https://www.ifixit.com/Answers/View/172978/iPhone+4+-+extra+metal+part,+not+contact+clip.
You can also check this video starting from minute 6:

The CHEERS Sleek 12 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 CHEERS Sleek 12 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 CHEERS Sleek 12 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 CHEERS Sleek 12 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/Guide/iPhone+14+Plus+Taptic+Engine+Replacement/153356

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

Rooted Devices/Custom ROMs: Devices with modified software (rooted, custom recovery, custom ROMs) often cannot install official OTA updates. Refer to specific repair guides for your phone model for detailed opening instructions. Look for signs of liquid damage indicators (LDI) or visible corrosion if you open the phone. Vibration/Noise: Loose components can rattle inside the phone, creating unwanted noise. Check for App Permissions: Ensure the camera app has necessary permissions. Clean with Compressed Air: Use short, controlled bursts of compressed air (holding the can upright) to blow out any loose debris. Carefully transfer all the small components identified in the previous step from the old mid-frame to the new one. Inventory Management: Keep a record of all sensitive parts, including their condition (new, tested good, faulty) and origin. Physical Impact: Cracks in the logic board or dislodged components near the PMIC. Features: It displays estimated battery wear, current battery capacity, design capacity, and charging/discharging speeds. If the new chip is a BGA (Ball Grid Array), you'd typically need a reballing stencil, but most magnetometers are QFN or LGA, allowing paste application to the board pads. The front-facing camera, often referred to as the selfie camera, has become an indispensable feature of modern smartphones. The jack consists of several contact points inside that make electrical connection with the plug on your headphones. Heat Gun or Hot Air Station: To soften adhesive for screen or back cover removal. Battery Health Monitoring Utilities: Apps like AccuBattery (Android) or desktop tools like iMazing (iOS) can provide detailed battery cycle counts, estimated health, charge/discharge rates, and temperature. Always Replace Shielding: During any repair, always make an effort to replace all internal shielding exactly as it was found. Sideload: In your command prompt/terminal (from within your `platform-tools` directory), type: `adb sideload ` (replace `` with the actual name of your downloaded OTA file). External: Carefully examine the sensor area (or the screen above it) for any physical damage like cracks, deep scratches, liquid residue, or excessive wear. Ensure all dust and smudges are gone, and no new ones have been introduced. A failed LED array can manifest in several ways: a completely black screen with the phone still on, a very dim display, flickering backlight, or uneven illumination (e.g., bright spots and dark patches). Preventing such issues involves performing clean software updates, avoiding untested custom ROMs, and always backing up data regularly. A broken trace typically results in the failure of a specific component or function directly connected to that trace. This security measure means that simply swapping a faulty sensor with a new, generic one will often result in a "fingerprint sensor not recognized" error or a complete loss of functionality. Replace any missing foam pads or small adhesive pieces that help hold components in place or prevent light leaks. Power Management IC (PMIC): Some network issues can stem from a faulty PMIC that supplies power to the Network IC. Disconnect all flex cables connecting the old screen to the logic board. For more advanced diagnostics, typically performed by professional technicians, a multimeter can be used to check for continuity on the camera module's flex cable and specific voltage rails on the motherboard that power the camera. It not only provides a powerful means to repair complex smartphone failures but also fosters a deeper understanding of electronics and circuit board design. Location and Securing: First, confirm the motor is in its intended location. Boot Loops or Soft Bricks: In severe cases, a completely dead baseband can prevent the phone from booting up correctly due to a critical system component failure.

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