Motherboard has no power - Clevo W650SC

[vcolella]

Hello all,

I've been for some time now trying to troubleshoot this Clevo W650SC laptop motherboard. It has no power, no charging lights, nothing. Now please bear in mind I don't have much experience with this stuff, so looking for some info online I decided to search for shorts.

Luckily I've managed to find this service manual.

VIN is not shorted and I'm reasonably convinced of a short on VDD3. I've desoldered most mosfets, disconnected coils and removed some caps without success in pinpointing the faulty component. The lowest resistance I could find was near ME and BIOS ROM (U27, U28), but desoldering these didn't fix the short.

Any ideas on how to go forward ? Thanks in advance !

[amyk]

Current-limited power supply and a thermal camera.

[vcolella]

Unfortunately a thermal camera is not really an option right now

[modoran]

Then use IPA to see what is getting hot. Is not as fast as a thermal camera, but it will din the job.

Inject 1V and a lot of amps into the circuit.

[vcolella]

Alright ! Just ordered a rosin short "detector", will try that as well as IPA. Any suggestions on where to inject the voltage ?

[amyk]

Apply power via VIN, since anywhere else could risk backfeeding and damage (there are often "discharge FETs" used to pull rails to ground quickly if the power sequencing determines they shouldn't be on yet.)