[SOLVED] I'm looking for Sendo S1 repair guide or schematics (free) - Phones & Tablets Forum

Hi,

I'm hoping you can help me out with my Sendo S1. 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.

@Mario

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 Sendo S1 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/ivangaj-go.3618330/
Take a look at comment #25
Also, this : https://www.ifixit.com/Answers/View/662650/Where+do+I+go+to+replace+the+sync+button+on+the+actual+console+itself.
You can also check this video starting from minute 10:

The Sendo S1 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 Sendo S1 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 Sendo S1 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 Sendo S1 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/htc-hd2-flaxcable-board-function-keys.658837/

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

Shielding: Ensure all metal shields and covers that go over the GPS circuitry are reinstalled correctly. Reason: Some older or cheaper data plans do not include hotspot/tethering functionality, or they have separate, lower data caps specifically for hotspot usage. Before attempting such an advanced repair, a thorough diagnosis is crucial to confirm the DAC is the culprit: Avoid Physical Damage: Protect your phone from drops and impacts, which can physically damage internal components, including the storage chip. Burnt Spots/Discoloration: Overheating due to a short circuit or excessive current can cause sections of the flex cable to appear discolored (brown, black) or even visibly burnt. While primarily for media playback, sometimes these can indirectly affect call audio. It won't delete personal data but will require you to re-enter Wi-Fi passwords and re-pair Bluetooth devices. Many issues resolve simply by replacing a faulty or substandard cable. Fine-Gauge Solder Wire (Lead-free or Leaded, depending on original): High-quality solder for secure connections. While these devices offer a glimpse into the future of mobile computing, their intricate design also introduces unique challenges when it comes to repair and maintenance. Double-check the color and any specific cutouts for buttons, ports, and sensors. Prepare New Component: Ensure the new backlight filter component is clean and free of oxidation. Conversely, some users might experience sound, but it is heavily distorted, crackling, or intermittently cutting out, regardless of the audio source or volume setting. Motherboard Repair: If the issue is with the connector on the motherboard or the home button control IC, this requires advanced micro-soldering and board-level repair, which is typically expensive and beyond the scope of most DIYers. Mastering the art of reading and interpreting schematics transforms a repair technician into a true electrical diagnostician, capable of tackling even the most challenging and seemingly "dead" devices.## 2. After removal, clean the solder pads on the flex cable thoroughly using solder wick and IPA (Isopropyl Alcohol) to remove any old solder residue and ensure a flat, clean surface for the new component. Crucial: Disconnect the battery flex cable from the motherboard as soon as the phone is opened, even if you couldn't remove it earlier. Disconnect the battery flex cable as the very first step to prevent short circuits and component damage. Before considering hardware intervention, it's crucial to exhaust all software-related troubleshooting steps. If you've removed old adhesive, clean off all residue from both the frame and the screen/back cover. If the buttons work correctly in these modes, an app might be the culprit. Power on the phone and immediately try to enable Bluetooth and search for devices. Insufficient Heat: Trying to pry without adequately softening the adhesive will lead to excessive force, potentially bending the frame, cracking glass further, or damaging internal components. Reliable Sources: Only download firmware, custom ROMs, or recovery images from trusted sources (e.g., official XDA Developers threads, manufacturer websites). Difficult Reassembly: A bent frame makes any subsequent repairs or reassembly extremely difficult, as parts simply won't fit correctly. A typical smartphone PCB consists of multiple layers of copper traces separated by insulating dielectric material. Noise Varying with Movement: The static changes (gets louder, softer, disappears, or changes character) when you wiggle or rotate the headphone plug in the jack, or when you gently press on the phone's frame near the jack. Antenna Cables/Modules: Disconnect and remove any antenna cables or modules. NEVER use metal objects (like a paperclip or needle) as this can bend the delicate charging pins or cause a short circuit. Component Identification: Using schematics and boardview, precisely locate the Memory Controller IC and note its orientation.

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