SescoTech Computers

26/04/2026

Charging Chip Data Communication testing with Dso

11/03/2026

31/12/2025

Laptop Repair Case Study | Complex I/O Controller Issue
Problem:
A laptop was received in a completely dead condition. On initial inspection, the AC section was not functioning properly.
Diagnosis:
During tracing, a short circuit was found on the 3.3V LDO line. Although the 3.3V LDO IC was generating voltage, there was no clock and data activity present. After detailed diagnosis, it was confirmed that the I/O controller was shorted.
Solution (First Repair):
The faulty I/O controller was replaced with a new IC. After replacement, the laptop powered on successfully and worked normally on Windows.
New Issue (After 1 Hour):
After approximately one hour, the laptop started powering on but:
Windows would not load
The system shut down automatically
BIOS showed abnormal readings
Observed BIOS abnormalities included:
Battery percentage showing beyond normal limits
Fan speed stuck at a fixed value
Abnormal BIOS interface behavior
This was a rare and unusual case.
Further Action:
The BIOS was reprogrammed, but the issue remained and the case became more complicated.
Final Diagnosis & Solution:
After a full day of deep diagnostics, suspicion again fell on the replacement I/O controller. A new I/O controller was ordered and replaced.
Result:
After replacing the I/O controller again, the issue was completely resolved.
The laptop booted normally, BIOS readings returned to normal, and the system operated stably without shutdown.
Conclusion:
This case highlights that:
Faulty or low-quality replacement I/O controllers can cause intermittent and abnormal BIOS behavior
Deep diagnosis and patience are critical in complex motherboard repairs
📸 Attached are images showing abnormal BIOS behavior, incorrect battery readings, and stuck fan speed.

31/12/2025

Fault Finding Game

31/12/2025

Capture Leackage

17/04/2025

11TH Genration Laptop repair Sucsessfully

13/04/2025

Laptop Leackage trace With Osiliscope

21/03/2025

Case Study: Laptop Power Issue Diagnosis & Repair

Today, I received a laptop with a power issue. The system would turn on but then shut down immediately. To diagnose the problem, I followed the power sequence step by step:

1. Checked the Charging IC requirements – Everything was fine.

2. Examined the Step Down section – No issues found.

3. Verified the IO requirements – All signals were present.

4. Checked the System Power OK signal – It was intact.

5. Analyzed the PLT_RST and CPU Reset signals – Both were fine.

6. Checked the DRAM Power Good signal – It was working.

7. Identified a missing RAM Reset signal – The required 1.35V on pin 30 was absent.

Tracing the Issue

I traced the signal path and found that the SOC chip was outputting the signal correctly to a resistor, and the signal was also passing through the resistor. However, it wasn’t reaching the RAM slot. Interestingly, there was no short circuit on that line.

Since this was unusual, I suspected a PCB trace issue. Upon close inspection under a microscope, I found a very minor break in a track. This break was preventing the signal from reaching the RAM slot.

Repair Process

1. Cleaned the broken track thoroughly.

2. Cut the track completely to ensure a clean repair.

3. Created a new connection using a jumper wire.

4. Rechecked the circuit to confirm continuity.

After completing the repair, I powered on the laptop, and it successfully booted with a display.

Conclusion: The issue was a broken PCB trace affecting the RAM reset signal. By carefully diagnosing and repairing the broken connection, I was able to restore the laptop’s functionality.

This case highlights the importance of meticulous circuit tracing and deep analysis using a microscope when dealing with power sequence failures.

13/03/2025

https://www.fiverr.com/s/e656XXP