[SOLVED] I'm looking for STRAWBERRY ST 22 repair guide or schematics (free) - Phones & Tablets Forum

Hi,

I'm hoping you can help me out with my STRAWBERRY ST 22. 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.

@Giovanna

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 STRAWBERRY ST 22 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/693898/How+can+I+fix+bugs+related+to+wifi+and+Bluetooth+in+my+iPhone+6plus
Take a look at comment #1709
Also, this : https://xdaforums.com/t/can-we-change-boot-animation-bootloader-unlocked.4420303/.
You can also check this video starting from minute 1:

The STRAWBERRY ST 22 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 STRAWBERRY ST 22 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 STRAWBERRY ST 22 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 STRAWBERRY ST 22 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/Answers/View/663332/Plan+to+fix+overheating+GPU+in+iMac:+thermal+pad+or+thermal+paste

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

For ICs, solder paste is usually applied to the pads on the flex cable. By using extenders, the technician can apply heat to one layer without directly subjecting the other layer to the same thermal stress, isolating the heat to the target area. Schematics & Boardview Software: Absolutely indispensable for identifying specific OCP/OVP ICs, charging pathways, test points, and component values. Screen Separation: Check if the screen assembly has separated or lifted from the phone's frame, especially at the corners or edges. Also, inspect the corresponding contact pads on the antenna module or frame for corrosion or dirt. Background Processes: Close unnecessary background applications that might be consuming CPU resources and slowing down audio processing. Full Boot/Idle: Once the phone has fully booted and is displaying the home screen, the current draw will stabilize at a lower idle level, fluctuating based on background tasks. Third-Party Tools: There are third-party hardware "boxes" and software (e.g., Z3X, Octoplus, UMT) that claim to "repair" or "write" IMEIs. If these creases are not sharp and the cable functions, they may be acceptable, but avoid introducing new, sharper ones. Virtually any smartphone component can be counterfeited, but some are more commonly targeted due to their high demand and perceived value: If a part isn't coming loose, recheck for hidden screws, clips, or adhesive. Be careful not to damage the earpiece speaker, front camera, or any other components that might be integrated with or adjacent to the flex. In most smartphones, the haptic motor is a small, self-contained module, often located near the bottom of the device or integrated into a speaker enclosure. Initial Troubleshooting: Rule out simpler causes like faulty components or software issues. If inspection reveals damage to the flex cable, or if reseating the connector doesn't resolve the issue, the most common fix is to replace the entire flex cable assembly that contains the ALS. Intermittent Vibration: The vibration works sometimes, but not consistently. If the wireless charging IC on the logic board is confirmed to be faulty (e.g., via thermal imaging, short detection), it will need to be replaced. By ensuring you have the correct replacement part and exercising a little care, you can easily perform this fix yourself.2. USB Protocol Analyzer: For complex USB-C charging issues, a protocol analyzer can decode the Power Delivery (PD) or Quick Charge (QC) negotiation to see why charging protocols are failing. Prepare Your Device: Power off your phone and remove the SIM card tray. It not only provides a powerful means to repair complex smartphone failures but also fosters a deeper understanding of electronics and circuit board design. Connector: Ensure the flex cable connector on the motherboard is clean and fully latched. If the basic checks don't resolve the issue, you'll need to delve deeper into the logic board. The goal is to very slightly increase the angle of the tongue so it makes better contact with the cable's connector. The presence of such debris is a strong indicator that there's an opening or a compromised seal, which often goes hand-in-hand with misalignment. As the wear progresses, the problems tend to become more persistent and severe, potentially leading to a completely blank screen, even though the phone itself may still be powered on and receiving notifications. Risk to Safety: If you encounter a severely swollen battery or suspect a major electrical fault. Incorrect Ejector Tools: Using a non-standard or blunt object (e.g., a thick needle, a screwdriver) can damage the internal spring or the ejector hole. Efficient storage of new and salvaged parts is crucial for quick turnaround times. A stripped head indicates that the screw is likely not properly tightened or cannot be removed easily.

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