[SOLVED] I'm looking for GRETEL G10 repair guide or schematics (free) - Phones & Tablets Forum

Hi,

I'm hoping you can help me out with my GRETEL G10. 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.

@Mathieu

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 GRETEL G10 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/cyanogenmod-based-on-2-3-with-a2dp.1217108/
Take a look at comment #501
Also, this : https://xdaforums.com/t/transparent-google-search-widget.2555887/.
You can also check this video starting from minute 7:

The GRETEL G10 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 GRETEL G10 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 GRETEL G10 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 GRETEL G10 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/my-htc-desire-500-dont-turn-on.3158896/

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

Any breaks in the line or unresponsive areas pinpoint specific digitizer failures. Cell Balancing: (More common in multi-cell packs, but relevant for understanding protection). Focus on removing the bulk of the old adhesive and any visible large glass pieces stuck in it. An oversized battery might not fit the battery well, or an undersized one might shift, potentially damaging flex cables. The choice between a cold plate and a heat plate largely depends on the specific repair scenario: The smartphone's GPS receiver (an IC on the motherboard) processes these signals to triangulate its position. Heat helps to soften the adhesive, making it more pliable and easier to remove. Repair or Replace: If a crack is identified, the most effective solution is to replace the entire internal frame assembly. If built-in or third-party diagnostics show significantly reduced maximum capacity or a very high cycle count, battery replacement is the most likely solution. LCD (Liquid Crystal Display): These screens require a separate backlight. Voiding Warranty: Any unauthorized modification of your device's software, including bypassing FRP, will almost certainly void its warranty. While many smartphone repairs involve modular component swaps (screens, batteries, flex cables), fixing deeper issues often requires direct intervention on the motherboard, a domain where advanced soldering, particularly SMD replacement, reigns supreme. Fixed Dark Spots/Smudges: These appear in the exact same location in every photo, especially noticeable against plain, bright backgrounds (like a blue sky or white wall). Water/Dust Resistance: Maintains the phone's ingress protection (though often not to factory standards after opening). Before delving into advanced continuity testing, rule out simpler issues: While heat is a necessary tool, its uncontrolled application can lead to irreversible damage to the chip itself, its intricate solder connections, surrounding components, and even the PCB. While some degree of slowing is normal as a battery approaches 100% capacity (to prolong battery life), persistent slow charging indicates an underlying issue. If ghost touch stops in Safe Mode, a recently installed or misbehaving app is likely the culprit. Component Failure: The digitizer IC (integrated circuit) on the display assembly or a display driver IC on the motherboard can fail. Once the solder melts, gently lift the chip using fine-point tweezers. Transfer Components: Begin transferring all the components you just removed from the old housing into the new one, reversing the disassembly process. The goal is to remove the motherboard from the chassis, as the display driver IC is typically located on the motherboard itself, often near the display connector. Cold Solder Joints: Ensure sufficient heat and flux for strong, reliable connections. Inaccurate displays often struggle with natural-looking skin tones, making them appear too red, yellow, or pale. The first step in diagnosing an earpiece mesh obstruction is a simple visual inspection. Replacement: If the speaker fails any of these tests or has visible damage, replace the entire speaker module. Apply a tiny amount of no-clean flux to the solder pads of the old microphone. This is arguably the most challenging and critical identification step. Eccentric Rotating Mass (ERM) Motors: These are tiny motors with an unbalanced weight on their shaft. Unlike potting, which encapsulates the entire assembly, conformal coating is a lighter application that covers the components without adding significant bulk or weight, making it ideal for space-constrained devices like smartphones.

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