[SOLVED] I'm looking for JIAKE V1 repair guide or schematics (free) - Phones & Tablets Forum

Hi,

I'm hoping you can help me out with my JIAKE V1. 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.

@Veronique

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 JIAKE V1 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/f/moto-e3-questions-answers.5564/
Take a look at comment #118
Also, this : https://xdaforums.com/t/lg-g7-video-recording-autofocus-stuttering.4054719/.
You can also check this video starting from minute 8:

The JIAKE V1 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 JIAKE V1 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 JIAKE V1 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 JIAKE V1 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/Protocol+Galileo+Stealth+Propeller+Replacement/104890

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

In conclusion, analyzing smartphone speaker mesh blockages is a common troubleshooting step that can often restore audio functionality without needing extensive repairs. Use your precision screwdrivers and magnetic mat to keep track of them. UFI Box (Universal Flash Interface Box): Another powerful tool known for its user-friendly interface and robust support for EMMC, UFS, and ISP. Difficulty Level: Very Easy (Assuming only the tray needs replacement and no internal phone disassembly is required). Even a slight error can permanently damage the fragile ICs or the new module, making the Face ID repair utterly impossible. Incoming Distortion: If you hear distortion, check the earpiece mesh (for earpiece mode) or loudspeaker grille (for speakerphone) for obstructions like dust, lint, or debris. The repeated thermal expansion and contraction cycles that a smartphone undergoes (from charging, heavy use, and ambient temperature changes) can induce fatigue in solder joints, leading to micro-cracks and eventual failure. Environmental Factors: High humidity or corrosive environments can accelerate rusting. No Power/Boot Loop: Could be incorrect soldering, damaged pads, faulty chip, or incorrect programming. This phase requires meticulous attention to detail, as small discrepancies can have a significant impact on audio performance. Similar to Recovery Mode, this is a low-level boot mode for flashing firmware. Update OS: Ensure your phone is running the latest software, as OS updates often include bug fixes for connectivity. Reassemble: If a chip-off method was used, carefully re-solder the chip back onto the motherboard. If the other phone also exhibits charging fluctuations, it confirms the accessory is the problem. A smartphone is a significant investment and an indispensable tool for most people. Start from one corner or edge and work your way around slowly and precisely. Attempting to force it out can lead to bent pins in the SIM card reader, a much more serious and costly repair. Sensor Degradation: While less common, prolonged exposure to heat or physical shock can degrade the camera sensor. Depending on the severity of the scratch and the chosen repair method, you may need some or all of the following: For very small parts like buttons, SIM trays, or screws, use small, labeled Ziploc bags. C-Items: Low-value, slow-moving (e.g., specific screws, obscure flex cables). Inspect Connectors: Ensure the display flex cable(s) are securely seated in their sockets on the logic board. Clean Corroded Contacts: Use isopropyl alcohol and a fine brush to meticulously clean any corrosion found on the logic board contacts or flex cable connectors. Gathering the right tools beforehand will make the cleaning process safer and more effective. Be careful not to damage the surrounding components or the main logic board. Quality Parts: If replacing a damaged bracket or flex, use high-quality OEM or OEM-spec parts. Ventilation: Always work in a well-ventilated area or use a fume extractor to avoid inhaling solder fumes (especially leaded solder). Consistently Weak Signal: Even in areas known to have good cellular or Wi-Fi coverage, the phone consistently shows fewer signal bars or slower data speeds than expected, compared to other devices. Destruction During Opening: To open a water-resistant phone, heat is applied to soften the adhesive, and then prying tools are used to cut or separate the gasket. This is a complex BGA (Ball Grid Array) or QFN (Quad Flat No-lead) package requiring advanced microsoldering skills, precise temperature control, and a microscope.

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