[SOLVED] I'm looking for DL YC-335 repair guide or schematics (free) - Phones & Tablets Forum

Hi,

I'm hoping you can help me out with my DL YC-335. 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.

@Solange

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 DL YC-335 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/626049/Can+I+use+different+size+of+Black+and+colored+ink+cartridge
Take a look at comment #1696
Also, this : https://www.ifixit.com/Answers/View/350240/Kodak+ESP3+owner+needs+a+power+supply+replacement.
You can also check this video starting from minute 4:

The DL YC-335 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 DL YC-335 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 DL YC-335 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 DL YC-335 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/bluetooth-logtiec-headset-with-htc-3600.345545/

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

Use the volume buttons to highlight "Reboot system now" and press the power button to select it. Bootloader: A low-level program that runs when your phone starts, responsible for initiating the operating system. Dry Thoroughly: Once clean, use compressed air to quickly dry the area. Download the correct stock firmware: Get it from a reputable source (e.g., official manufacturer support site, XDA Developers forum for verified firmwares). Acoustic Ports: Crucially, ensure that the tiny acoustic port (the hole allowing sound into the microphone) is perfectly aligned with the corresponding hole in the phone's frame/casing. Physical signs often include a loose connection with the charging cable, bent or broken internal pins, or visible corrosion within the port. Carefully remove the back cover or display assembly, depending on the phone's design. Check for Software Updates: Ensure your phone's operating system is up to date, as bugs can sometimes affect charging functions. Unlike the primary microphone, which is usually found at the bottom of the device near the charging port, auxiliary microphones are typically situated in other strategic locations. Hot Air Rework: Set your hot air station to an appropriate temperature for lead-free solder (e.g., 350-380°C) with a moderate airflow. Patience and a methodical approach are key to successfully resolving this common smartphone problem.8. The shielding cans are typically soldered to ground pads on the mainboard. Vapor Inhalation: Inhaling high concentrations of IPA vapor can cause dizziness, headaches, nausea, and, in extreme cases, central nervous system depression. Power Off Completely: Turn off the smartphone to prevent accidental shorts or damage during manipulation. Windows: Navigate to your `platform-tools` folder, then type `cmd` in the address bar and press Enter. Hot Air Rework Station: For separating and rejoining logic board layers, and for IC replacement. Plastic prying tools (spudgers): To separate panels and disconnect flex cables. In summary, assessing smartphone USB charging fluctuation requires a methodical progression from testing external components to inspecting the internal port, leveraging software monitoring for real-time data, and using dedicated hardware tools for precise measurements. Water damage and corrosion are notorious for causing dead shorts, destroying ICs, rendering connections open, and corrupting data. The main "tools" will be built-in phone settings, third-party storage analyzer apps, and potentially a computer with ADB (Android Debug Bridge) for more advanced diagnostics. This prevents any power from flowing through the board and eliminates the risk of accidental shorts. After checking with pure black, switch to a dark grey test image (e.g., #333333 or #666666 RGB). Never exceed the working voltage of the circuit you are injecting into. Multimeter: With continuity test function for diagnosing and verifying connections. This skill transforms guessing games into evidence-based problem-solving.5. Disable Find My iPhone (Optional but Recommended): If your phone can boot sufficiently, disable "Find My iPhone" in Settings > Your Name > Find My. Schematics will provide the component's part number and location on the PCB, often labeled as "MAG," "COMPASS," or by its manufacturer's specific IC code (e.g., AKM, Bosch, STMicroelectronics). While primarily a repair tool, the controlled heat from a hot air station can provide crucial insights into a device's malfunction. Go to "Settings" -> "Apps" -> select your browser (e.g., Chrome, Firefox). Gently nudge the component with your tweezers if necessary to ensure it settles correctly.

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