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Update on this one: I actually noticed we had used an incompatible ISL (9900); I replaced with the correct one (9901) and the symptoms changed slightly; now PPBUS_AON cycles from ~11v to 12v, over and over. Not sure if this matters with regards to diagnosing this specific issue, but wanted to include it. -
820-02918 PPBUS Cycling, Minor Liquid.
Working on an 820-02918 board that had a minor liquid spill, but it was directly to the ISL/U5200. Essentially the entire area had to be replaced due to corrosion. Got it all cleaned up and everything looks good and checks out, but we're hitting a cycling PPBUS issue now. PPBUS_AON cycles quickly from ~9v-12v, indefinitely.
Knowing this is typically a sign of a possible short on a lower rail, we checked all around and found no obvious damage or shorts. We have VERY LIMITED parts for this model (exactly 1 single U5200 chip), but I suspect it will end up being a continuity issue or another component damaged by proxy during the original spill event.
Since this is the very first 820-02918 board we've seen and worked on, I figured I'd go ahead and ask the experts! Without a solid PPBUS, I figured we need to start there and get it stable first. Any and all help is very much appreciated!!
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Just wondering if anybody has seen this issue. I'm assuming that all of the CD3217's are semi functional for the chips to request 20V from the PSU.
This unit had some soda spattered up into the side vent. I ultrasonic cleaned the board, now getting this weird sometimes requesting 20V behavior, then it goes back to 5.2V ~ 25mA The U3200 jack cycles.
I'm hoping this is just an issue with some components between the TOP Jack and U3100 and not U3100 itself.
Not seeing anything unusual on thermals just some of the power supply inductors getting warm when it's requesting...08-25-2025, 01:13 PM -
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... -
Hello everybody, I could use some help on this one... It's got me guessing...
I took pictures of all the boards and the pin out of the connector on the power supply that goes to the main board... I measured all the pins in relation to chassis ground, here are the result.
(B13v)1. 12.7 volts cycling (Vamp) 2. 12.7 volts cycling
(B13v)3. 12.7 volts cycling (PWM5) 4. 1.0 volts cycling
(OD_LE)5. 2.8 volts cycling (PWM4) 6. 0.9 volts cycling
(OD_ON)7. 2.8 volts cycling (PWM3) 8. 0.9 volts cycling
9. ground (PWM2) 10. 0.9 volts cycling... -
Hello guys. I got this motherboard that had liquid damage. The motherboard's type-c controller IC got shorted which resulted in main power rail failing to be produced and after replacement of the IC the main power rail returned. But the board is turning on and off. The current consumption is around 0.120Amps@20volts. After like 10 seconds it turns off and on endlessly. Checking the voltages on the coils:
pl701-9.04 volts
plpl101-5.1 volts
pl201-1.2 volts
LT1-0(0.685kohms)
pl301-1.05 volts
pl100-3.3 volts
pl614-1.04 volts
pl402-0.9 volts
pl613-0...03-21-2024, 05:49 AM -
TLDR:
Are these voltage readings normal? What should I do next?
Long story:
I have an Asus FX505GT laptop that received a small amount of liquid.
Since then, installing the Intel GPU drivers causes a black screen, then an infinite Windows loading until I uninstall the driver using safe mode.
The laptop still works when using the default Microsoft display driver, but the video memory shows as unknown in hwinfo.
Installing the GTX 1650 max-q drivers works, but there does not seem to be any acceleration....12-07-2022, 02:54 PM
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