Schematics for HP/Compak NX9110 Notebook Main Board

Alf Katz · 2006-11-18T09:23:29+00:00

I have a dead HP/Compak NX9110 laptop. Of course HP have quoted a new motherboard price that is higher than the value of the laptop.After investigating a ~3 Hz ticking sound, I have narrowed the problem down to a MAX1902 multiple output switching regulator which regulates the 3V and 5V supplies. Nice looking device really. It looks like the device is being shut down via the Time/ON5 input. However, I can't see what is driving this input (naturally it's a multilayer board making further diagnosis difficult).It doesn't seem to be going into current limit, or tripping either the overvoltage or undervoltage circuits.What would really help is a mainboard schematic. Does anyone have one they can scan, or know where to find one?Thanks,Alf

Nov 18, 2006 21 Replies

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mike 19 years ago

Don't know about English made, but the Programmer's Reference Guide for my C64 had a schematic in the back. mike

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mike 19 years ago

What do you see when you look at the outputs of the supplies with a scope?

First thing I'd try is to bridge a big cap at each of the voltage outputs. Designers are expecting too much out of filter caps these days. They go open and the first pulse out of the switch overvoltages the system. Since there are multiple feedback and control paths, it's not always easy to see.

I have a HP LCD monitor with an open cap. The power supply put out

20V spikes on the 5V line as part of the shutdown cycle. Fixing the cap fixed the supply, but the control processor has taken offense and died. mike

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