USB power management IC location on T43 system board?

[SteveS]

One of the T43 machines I own gives a “Power Surge on Hub Port” error message after it warms up. Clicking the bubble shows that the top USB port in the list (which is not numbered) shows “Unknown USB Device", with the remaining 7 showing “Unused Port” I believe the offending port is the one that serves the docking connector, as my USB mouse and keyboard freeze when the error appears when using the Port Replicator II. The two side mounted USB ports remain functional. The error appears with or without the dock attached.

I am not too found of the idea of shelling out $400 or so for a new system board, so I would like to try to repair it first. I believe it may be a solder problem as it appears when the system board is flexed just a slight amount. I have been running the machine with the palm rest and bezel removed, with the keyboard in a double plastic bag to prevent shorting something out. I was hoping to isolate the problem with freeze spray, but it is very intermittent, although flexing just about any part of the board invokes the error.

I did a quick visual with a magnifying glass looking for solder problems, but I don’t know where to look, and what I saw looks OK. I did not peel up any of the insulating plastic which covers some ICs on either side or the board.

The system board is FRU# 39T0476. The model is 2686 E7U, with the SXGA+ display.

Has anyone ever seen this error? It looks like 4 USB ports come out of the Intel 82801 chip, which provides most of the system IO. But this is the data pair only, not the USB power management. That is probably done in another chip somewhere. Any ideas where, and if there are any chips further downstream between it and the docking port? I know that it is quite common to use extra USB ports internally for on-board devices in laptops, although I don’t know if the T43 does this. I have removed the modem and wireless LAN cards, along with the PCMCIA expander, and the error will still appears.