Hi People,
i have a really strange fault on a laptop, which i am reparing. It's a Lenovo Thinkpad L13 18834-1M.
Visually I could see that PU4501 (TPS51393RJER-GP) was burned so I removed the IC and ordered a spare part. Looking into Schematics showed, that the IC is responsible for the 3.3V rail. I noticed, that after removing the IC there is still a short on that bus (0.4 Ohm). Furthermore PU5201 & PU4551 are also short. Voltage injection showed a huge current drawn of up to 2.5 A but with only a slight temperature flickering at U4004 (TPS22976DPUR-GP) using ethanol. I removed that IC too and the short is still present. IC appears to be fine after testing.
Although taking the great amount of current at 3 V I could not find any component getting hot. Also CPU is not hot at all.
Using the USB-C charger there is no input voltage present when battery is disconnected. With battery attached, I get 12V at Vin. Vin seems to not be short. EC seems to not function, since the charging LED does not turn on. However, I can confirm 12V also being present at the battery + side. So I guess it's charging. When battery is attached alone, it's less than 1 V so indicating, that the battery is entirely empty.
Does anyone have an idea to identify the fault?
Thank you very much in advance!
All the best
Cool-Oase
i have a really strange fault on a laptop, which i am reparing. It's a Lenovo Thinkpad L13 18834-1M.
Visually I could see that PU4501 (TPS51393RJER-GP) was burned so I removed the IC and ordered a spare part. Looking into Schematics showed, that the IC is responsible for the 3.3V rail. I noticed, that after removing the IC there is still a short on that bus (0.4 Ohm). Furthermore PU5201 & PU4551 are also short. Voltage injection showed a huge current drawn of up to 2.5 A but with only a slight temperature flickering at U4004 (TPS22976DPUR-GP) using ethanol. I removed that IC too and the short is still present. IC appears to be fine after testing.
Although taking the great amount of current at 3 V I could not find any component getting hot. Also CPU is not hot at all.
Using the USB-C charger there is no input voltage present when battery is disconnected. With battery attached, I get 12V at Vin. Vin seems to not be short. EC seems to not function, since the charging LED does not turn on. However, I can confirm 12V also being present at the battery + side. So I guess it's charging. When battery is attached alone, it's less than 1 V so indicating, that the battery is entirely empty.
Does anyone have an idea to identify the fault?
Thank you very much in advance!
All the best
Cool-Oase
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