HP Touchsmart 520 - IPISB-NK

[IHackStuff]

So I've been working on this motherboard for a while now. I have the schematic pdf of a very similar (but just different enough to be annoying) motherboard. It will work, rarely. The rest of the time, it powers up and just sits there. No POST. No error beeps when I pull the RAM. Nada.
I went all over the board checking voltages and power_ok signals. VAXG wasn't coming up, so I forced it by changing a resistor value. After that, it worked a few more times, and I thought I had it solved. But, I was wrong, and now it's dead again.

Any ideas or tips of where to look now would be greatly appreciated.

[KE0ITR]

I had a similar problem with one I worked on. I ended up swapping the processor and it worked fine afterwards. The symptoms I had were it would turn on, but the LED for the power button (white) would not come on, and the CPU fan ran at 100%. No system beeps or any other indications.


After the cpu swap the system has worked fine for the last 3 months.