[SOLVED] I'm looking for KXD D70 repair guide or schematics (free) - Phones & Tablets Forum

Hi,

I'm hoping you can help me out with my KXD D70. 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.

@Joseph

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 KXD D70 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/Guide/Lenovo+Tab+2+A7-20F+LCD+Screen+Replacement/99629
Take a look at comment #403
Also, this : https://www.ifixit.com/Answers/View/792611/I+need+Samsung+SGH+C450+back+&+front+panels,+do+I+get+it.
You can also check this video starting from minute 10:

The KXD D70 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 KXD D70 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 KXD D70 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 KXD D70 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/calling-screen-bug.3951509/

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

Antenna Cables/Modules: Disconnect and remove any antenna cables or modules. Access: Access to these tools is generally restricted to authorized service centers. Bent Pins: Very gently attempt to straighten them with fine-tipped tweezers or a needle. This usually involves removing a small metal bracket securing the connector, then gently prying the FPC connector straight up. Missing Features: Some replacement screens might lack features like ambient light sensors or proximity sensors, or their functionality might be impaired. Incorrect Colors or Color Shifts: Gamma correction issues or data conversion errors. Modern smartphone camera lenses are often made of sapphire glass or hardened glass, which are much harder and less susceptible to these DIY methods. Halide Content: Lower halide content is generally preferred as halides can contribute to corrosion. NAND corruption/failure: The phone cannot read the bootloader or OS from the storage. Physical Damage: Drop impact damaging the sensor module or its internal components. Take Photos: Document all signs of liquid damage with clear photos for your records and for the customer. Earpiece Speaker/Front Sensor Flex: In many designs, the secondary mic is part of the same flex cable as the earpiece speaker or front sensor array (proximity/ambient light sensors). Given the critical role of the USB-C port, its failure necessitates prompt and often precise repair. Magnetic Dust: Over time, fine magnetic dust particles can accumulate around the OIS coils and magnets, interfering with their precise movement. Test SIMs in Another Device: If possible, insert both SIM cards into another known-good dual-SIM phone. Software Glitches: While less common for direct coil overheating, software issues could lead to excessive power draw in background processes that contribute to overall phone heat during charging. Apply New Adhesive: If your new display assembly doesn't have pre-installed adhesive, apply new, thin, even adhesive strips around the perimeter of the phone's frame where the screen will sit. Heat Gun or Hair Dryer: To soften the old adhesive and for initial phone opening. Instructions to enter these modes typically involve pressing a combination of volume and power buttons while powering on the device. They are typically part of a larger mid-frame assembly that includes critical structural elements. The new/repaired shield might not be properly grounded (bad solder joints). Issues can range from no audio whatsoever, to distorted sound, only one channel working, or physical obstruction. Solder Wick (Desoldering Braid): Used to meticulously clean up residual solder from the pads after the connector has been removed, ensuring a flat and clean surface for the new connector. Filters/Duplexers: Small RF filters can be damaged by liquid or impact. Perform a factory reset from within the phone's settings (if accessible) or from recovery mode ("Wipe data/factory reset"). The causes of a smartphone battery overheating can be broadly categorized: Smartphones, being ubiquitous and increasingly integrated into our daily lives, have become prime targets for malware. Visual Inspection: Carefully examine the screen for any visible cracks, even hairline ones, chips, or pressure marks. Note: Keep meticulous track of all screws, noting their sizes and locations. An open circuit (no beep, OL reading) indicates a severed ground connection.

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