Lenovo G40-30 NM-A311 - U401 burning

[ktmmotocross]

Hello.
Have this Lenovo G40-30 NM-A311, that have U401 /3,3ALW/burning.

I replaced it but still the same. no short on any rail. when i remove coil 3,3V is there. so i inject 3,3V, but when i inject it the the EN signal FROM KBC is lost.

any hints? every voltage is ok when removed PJP

[mcplslg123]

Re: Lenovo G40-30 NM-A311 - U401 burning

Was that IC burnt before it came to your bench?? If so then check VIN 19V pin resistance to ground. Had a similar case on HP Quanta U81 mb where 3.3v IC get burnt though no short on jumper and coil. I found that 19v Vin was showing 430 resistance to gnd whereas it should be close to infinity. May be this is the issue. Just check once.

[ktmmotocross]

Re: Lenovo G40-30 NM-A311 - U401 burning

close to infinity.