Hello,
Can you help me troubleshoot this laptop?
Model: Lenovo Thinkpad T480
Symptoms: When pressing the power button, powers on : power button is lit, the fan starts spinning, but it stops after a few seconds. Then the fan starts again, very fast. No picture. Same behavior with or without battery (which is charging fine by the way).
Current drawn:
- when plugged in and powered off, without battery : 45mA @ 19.9V
- when I press the power button, current jumps to 620mA, then goes up fast to 1.3A, and stays at 1.3A. Fan spins very fast.
Main power rail is not shorted, and I observe fairly low resistance values on many of the main inductors (7, 10, 12, 22 Ohms for the coils next to the CPU; 63 and 65 Ohms on other coils)
When the laptop is on, I do have 3.3 and 5V power rails, as well as lower voltage power rails. Note: I only have 10.2V on the main power rail, I don't know if it's normal.
CPU gets hot when current drawn is 1.3A, and fan is spinning fast. I have checked voltages on coils next to the CPU, I read 1.22V, 1.22V and 0.77V.
What surprises me is the high current drawn by the board. Without battery it shouldn't go and stay this high, should it?
What do you think? Does it sound like a shorted CPU? How can I confirm this diagnosis?
Regards,
mkdj
Can you help me troubleshoot this laptop?
Model: Lenovo Thinkpad T480
Symptoms: When pressing the power button, powers on : power button is lit, the fan starts spinning, but it stops after a few seconds. Then the fan starts again, very fast. No picture. Same behavior with or without battery (which is charging fine by the way).
Current drawn:
- when plugged in and powered off, without battery : 45mA @ 19.9V
- when I press the power button, current jumps to 620mA, then goes up fast to 1.3A, and stays at 1.3A. Fan spins very fast.
Main power rail is not shorted, and I observe fairly low resistance values on many of the main inductors (7, 10, 12, 22 Ohms for the coils next to the CPU; 63 and 65 Ohms on other coils)
When the laptop is on, I do have 3.3 and 5V power rails, as well as lower voltage power rails. Note: I only have 10.2V on the main power rail, I don't know if it's normal.
CPU gets hot when current drawn is 1.3A, and fan is spinning fast. I have checked voltages on coils next to the CPU, I read 1.22V, 1.22V and 0.77V.
What surprises me is the high current drawn by the board. Without battery it shouldn't go and stay this high, should it?
What do you think? Does it sound like a shorted CPU? How can I confirm this diagnosis?
Regards,
mkdj
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