[SOLVED] I'm looking for TELPO TPS450 repair guide or schematics (free) - Phones & Tablets Forum

Hi,

I'm hoping you can help me out with my TELPO TPS450. 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.

@Hanna

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 TELPO TPS450 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/28756/Replaced+LCD+shows+strange+Colors.+Whats+Wrong
Take a look at comment #1695
Also, this : https://xdaforums.com/t/q-help-with-rom-liquidsmooth-v2-9.2833392/.
You can also check this video starting from minute 9:

The TELPO TPS450 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 TELPO TPS450 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 TELPO TPS450 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 TELPO TPS450 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/314514/Need+to+replace+Cracked+Visio+E601i-A3+screen.

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

Reboot to Safe Mode: On Android, booting into Safe Mode disables all third-party apps. Charger and Cable: This is by far the most common reason for slow charging. If, after all these analytical steps, storage performance remains significantly degraded, especially after a factory reset, it points towards hardware degradation of the NAND flash memory. When this shielding is damaged or missing, it can lead to unexpected shorts, degraded performance, or increased vulnerability of delicate internal components. Manage Storage: Keep sufficient free internal storage (aim for at least 15-20% free). Built-in Android Dial Codes: Many Android manufacturers have hidden diagnostic menus accessible via dialer codes (e.g., `#0#` for Samsung, `##4636##` for general info). If software optimization and a factory reset fail to yield improvement, the issue likely points to hardware degradation, particularly of the internal storage, warranting professional attention. This step cannot be stressed enough , residual dust or smudges will ruin your photos. If something isn't working, immediately power off, disconnect the battery, and recheck all flex cable connections and component placements. Expected Result: The multimeter should beep (indicating continuity) and show a very low resistance reading, typically between 0.1 and 10 ohms (often less than 1 ohm for power coils). While some specific phone models might allow for the replacement of a separate, intermediate display flex cable (e.g., a specific FPC that bridges the main display flex to the logic board), for the vast majority of modern smartphones, a damaged "display flex cable" implies that the cable integrated into the display panel itself is faulty. Reassemble the Logic Board: Carefully reinstall the logic board into the phone frame. Navigate with volume buttons, select `Wipe cache partition` with the power button. Restart: Once at a normal temperature, restart the phone and try charging. Cleaning Liquid Damage: If minor corrosion, cleaning with isopropyl alcohol might help. This guide provides a comprehensive, step-by-step approach to diagnosing and fixing this critical error, ranging from simple recovery actions to more advanced flashing procedures. A loose headphone jack is a common problem that, with careful diagnosis and the right approach, can often be effectively repaired. Android: Go to `Settings > Location > Location services` or `Settings > Location > Advanced`. Dust under the screen protector or glass can sometimes mimic a pixel issue, but it can be wiped away. In diode mode, place the red probe on ground and the black probe on the suspicious line (or vice-versa, depending on your meter). Multiple Batteries: Many folding phones utilize two separate battery cells, one in each half of the device, increasing the complexity of battery replacement. Painting: Fine-detail model paint (acrylic or enamel), plastic-specific primer, clear coat sealant (matte or gloss), fine paint brushes or airbrush. Rather than traditional external whip antennas, contemporary devices embed multiple specialized antennas directly within the phone's structure , often as flex circuits, etched lines on the PCB, or integrated into the frame. Separate with Plastic Tools Only: Slowly and carefully work your way around the edges using only plastic opening picks. This threshold varies, but it's often more than just one or two pixels. Excessive pressure, even with a clean microfiber, can still cause scratches if an unseen particle is trapped. This method has the highest risk of battery deformation or damage if rushed. Consult Schematics/Boardview: Use software like ZXWTools, Refox, or official service manuals to pinpoint the exact location and identify the sensor's component designator (e.g., UXXXX). For photos, it can contribute to sharper results by aligning multiple rapidly captured frames (computational photography) or correcting subtle motion during a single exposure. Action: Advise the customer to contact the official service center first.

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