16IAH7H minor liquid damage around GPU buck. boardiew and schematic included.

[GGEZ]

Hi. I have a lenovo 16IAH7H (NM-E231) with a small amount of water spilled on the RT8816CGQWGPU buck converter. When powering on, keyboard lights up, fans will spin slowly. CPU and GPU are getting hot. No image. Not via HDMI either.

Part number is PU4001. The liquid spillage looked minor so I cleaned it up with some alcohol and cleaned ups some crusty joints with solder and flux.

BoardView and schematic is provided. The buck converter diagram is on PAGE 107.


I'm inquiring about any troubleshooting tips like probe points to measure and such. I can access a hot air station and micro soldering tools if necessary. Any tips and suggestions would be greatly appreciated. thanks.

[MOD EDIT] Link to schematic/boardview https://www.badcaps.net/forum/troubl...15#post1719615

[mcplslg123]

Are you getting output on coil from PU4001?

[GGEZ]

Are you getting output on coil from PU4001?

Hi.Thank you for the reply.
Yes im getting .75v from coils. and 1.25V on VRAM

Im only getting voltage on one side of the coils. is that normal?

[mcplslg123]

You must be measuring the coil with multimeter and its normal not to see anything on the other side. With DSO you should get a voltage on one side and pwm pulses on another side.
Just make sure both ends of the coil is beeping when measured in diode mode with multimeter.

[GGEZ]

Multimeter is beeping on both sides. Interesting that voltage can only be measured on one side. Learning something every day!
Resistance to GND on all coils are just 0.3-/.4 OHMS.

[GGEZ]

I have seen some videos from "Laptop Repair School" on YouTube that the CPU intel Intergrated graphics will boot before the big GPU takes over. So technically i should have a boot screen and since I'm not even getting an image at post, I'm starting to think that this could possibly some other issue than GPU. Maybe BIOS? Is it possible to probe for a "ALL_SYS_PWRGOOD" type of signal I could do for Lenovo laptops?