[SOLVED] I'm looking for CTL Chromebook Tab Tx1 repair guide or schematics (free) - Phones & Tablets Forum

Hi,

I'm hoping you can help me out with my CTL Chromebook Tab Tx1. 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.

@Saber

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 CTL Chromebook Tab Tx1 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/924346/Temporarily+joining+the+two+halves+of+a+logic+board
Take a look at comment #1427
Also, this : https://www.ifixit.com/Answers/View/391600/broken+cooling+assembly+part.
You can also check this video starting from minute 7:

The CTL Chromebook Tab Tx1 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 CTL Chromebook Tab Tx1 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 CTL Chromebook Tab Tx1 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 CTL Chromebook Tab Tx1 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-exterinal_sd-folder-not-working-after-4-0-3-install.1518660/

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

The problem often develops gradually, as dust and debris accumulate over weeks or months, making it easy to dismiss initially as a poor network connection or a caller's microphone issue. Re-seal and Close Phone: If all tests are successful, power off the phone. Carefully connect its flex cable to the motherboard, ensuring it's fully seated. Manufacturing Defects: Although less common, a faulty component can fail prematurely. Water resistance ratings are for accidental splashes, not intentional cleaning with water jets into tiny openings. Visual Inspection: Under a microscope, look for physical signs of damage: cracks, chips, burns, discoloration, or if the component is missing entirely. Physical Impact: Drops and impacts can cause stress on the board, leading to microscopic cracks in traces, especially near BGA chips or connectors. Excessive ripple indicates poor power filtering, which can be a source of EMI. Antenna Performance: Avoid covering or interfering with antennas (Wi-Fi, cellular, Bluetooth, GPS) with shielding materials unless specifically designed for that purpose, as this can degrade signal performance. Thermal Camera: While a coil itself might not get excessively hot unless it's shorted or dissipating a lot of power, a thermal camera can help identify an open coil by showing that subsequent components in the power rail are cool (not receiving power) while the component feeding the coil might be normal or even hotter if it's trying to push current through an open circuit. Work in a clean, well-lit, and organized environment to minimize the chance of losing tiny screws or damaging components. One-Way Audio (Recipient Hears You, You Don't Hear Them): This specifically points to an earpiece or audio output issue. Locate the GPS IC (often integrated with the Wi-Fi/Bluetooth IC, sometimes part of the main PMIC or baseband). Forcing screws can strip threads on the posts, damage the motherboard, or even crack the PCB. Faulty or failing components, such as a shorted capacitor, a struggling power management integrated circuit (PMIC), or an overloaded processor, can also generate abnormal heat. Safety First: Always power off the phone and disconnect the battery before attempting any disassembly. For soldering, temperatures are higher (300-400°C), but equally critical to get right. Phase 2: Locating the Short with a DC Power Supply (The "Short Killer" Method) Use a plastic spudger or fine-tip tweezers to gently pry straight up on the metal collar of the connector. Remove Screws and Brackets: Once the back cover or display is open, you will typically find various small Phillips, Torx, or Pentalobe screws securing metal shields and component connectors. Smartphone repair shops are unique environments where valuable, data-rich devices are routinely disassembled and left exposed. Then, dampen a lint-free cloth with isopropyl alcohol and meticulously wipe down the entire frame where the new adhesive will sit. Diagnosing distorted earpiece audio can range from a simple cleaning job to a complex micro-soldering repair. The final result should be shiny, silvery-tinned pads, indicating that the gold has been effectively "washed away," and the underlying nickel/copper is properly wetted. Metal tools can easily scratch, dent, or deform the frame, so use them sparingly and with minimal force. A capacity below 80% or performance management active is a strong indicator of a failing battery. For specific areas of interest or suspected damage, macro photography becomes necessary. The golden rule: use only non-conductive tools and be incredibly gentle. 90%+ Isopropyl Alcohol (IPA): For cleaning flux residue and board surfaces. Screen/Touch Not Working: This is unrelated to the antenna, but often occurs if the display/digitizer flex cables were not reconnected properly or were damaged during reassembly.

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