[SOLVED] I'm looking for Siemens C35 repair guide or schematics (free) - Phones & Tablets Forum

Hi,

I'm hoping you can help me out with my Siemens C35. 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.

@Ignacio

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 Siemens C35 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/807183/Mi+power+bank+balge
Take a look at comment #237
Also, this : https://xdaforums.com/t/q-problems-with-location.4097911/.
You can also check this video starting from minute 3:

The Siemens C35 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 Siemens C35 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 Siemens C35 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 Siemens C35 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/q-recover-data-red-triangle.2533537/

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

While a factory reset is usually the go-to solution to restore device functionality, it invariably leads to complete data loss. Component Alignment: They ensure components are seated correctly and consistently, which is vital for proper connection and function. If your phone has optical image stabilization (OIS), and it’s also failing, it might present similar symptoms, but a specific focus actuator issue will manifest primarily as an inability to acquire sharp focus. Proximity Sensor: Uses infrared light to detect objects close to the screen. If the digitizer controller IC is on the motherboard (less common now), inspect it for physical damage, liquid damage, or overheating. Eye Protection: Use safety glasses, especially when soldering or using a heat gun. For instance, `camera_service_died` points to the camera module, its power supply, or flex cable. Common issues include the switch becoming loose, unresponsive, stuck, or simply failing to register its position correctly. They are more energy-efficient for short bursts but can be more complex to drive. When this seal is compromised, whether due to a screen replacement, a prior repair, or manufacturing defect, the sensor's performance degrades, leading to frustrating recognition failures. For hot air, apply even heat to the switch until all pads reflow and the switch settles firmly. Crucially, on iPhones, the fingerprint (Touch ID) function is tied to the original button's secure enclave and cannot be transferred to a new, non-OEM button. Align it precisely over the pads on the logic board, ensuring its orientation matches the original (this is where your reference photo helps). Demanding Applications/Usage: Heavy gaming, prolonged video streaming, graphic-intensive apps, or running many applications simultaneously push the SoC to its limits, generating significant heat. No Touch Response: The entire screen, or specific rectangular areas of it, becomes completely unresponsive to touch. Connectors are tiny, and subtle damage is easily missed without proper magnification. For most Android phones: Press and hold the Power button and Volume Down button simultaneously for 10-20 seconds. If using a preheater, set it to around 100°C to 120°C and allow the board to stabilize. Foreign objects can bridge contacts, tricking the phone into thinking a charger is connected. IMEI Verification: Check the new IMEI number (usually in Settings > About phone or by dialing #06#) and ensure it's valid and matches any documentation provided with the new motherboard. Go to your phone's Settings > Connected devices > Bluetooth, and toggle the switch off, wait 10-15 seconds, then toggle it back on. Ensure it sits flush and properly engaged with any alignment pins or grooves. The phone might also experience slow performance, freeze, or restart unexpectedly, especially when trying to access data from the SD card. Battery Swelling: In rare cases, a severely swollen internal battery can put pressure on internal components and flex cables, stressing and potentially damaging connectors. This ensures that your navigation apps work flawlessly and your phone continues to be a reliable guide in the real world. Anti-static Wrist Strap/Mat (Recommended): To prevent electrostatic discharge (ESD). If it works on another computer, the problem is definitively with your original computer's setup (drivers, ports, software conflicts). Place the old, damaged shielding (if available) onto the new material as a template. This intricate process, combining careful assessment, meticulous trace repair, precise component reattachment, and structural reinforcement, highlights the depth of expertise required to work at the component level of modern smartphone electronics.3. Aftermarket (Low Quality / Copy / Generic): Cheap imitations, often using inferior materials and manufacturing processes.

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