Maybe this is a useful info for someone with LAN connection problems:
My ThinkPad R40 had a loose connection with its LAN connection.
I thought it was a loose conducting path of the RJ45 jack (this is the LAN jack) but i was wrong. I soldered the RJ45 pins but no luck. I even replaced the RJ45 jack with another one but again no success.
The LAN came back only if i was bending the circuit board at the upper left corner.
I've seeked a long time in the internet for the schematics of the R40 and then i've found it.
There i saw that the IC HB914-3A is connected to the RJ45 jack and it is in the area where my bending let the LAN came back. So i soldered all the pins of that IC and that was the solution.
The LAN connection is all right again




