T60 strange issue

[PuuFa]

When I plug in the power cord; the power led and the battery led are lit up normally. But when I press the power button; both lights immediately switch off and absolutely nothing happens, no fan movement or anything. The machine becomes completely dead until I reconnect the power cord and battery, after which it's the same thing again.

However, it powers on perfectly normal on battery power and as soon as the fan spins up I can connect the power cord and it works! I can connect and disconnect the cord when the system is up and running with no problems, Windows 7 runs stable and I've found absolutely nothing wrong with it except that it cannot be powered on when the power cord is connected. Same applies to waking up from stand by. Have to briefly disconnect the power cord or it will die and have to reconnect the battery to be able to power on again.

Sometimes the problem disappeared for a few days but reappeared again with no warning.

Things I've tried:
-flashed the latest BIOS
-another battery
-another 90W power supply
-another power jack
-another keyboard
-another LCD assembly
-another RAM
-stripped off every component that's not essential for powering up the system

None of the above helped so it's quite clearly a motherboard fault. Any hardware gurus around who'd have some ideas what could be done to repair this? I don't have experience on this kind of repairs but I've done a few SATA mods to T43's and X41's among other similar mods so I suppose I've got the right equipment and soldering skills. Just need advice what to do.

The board has X1400 graphics if that makes any difference.

Thanks in advance!

[ajkula66]

FWIW...

I've had the exact same set of symptoms on a T42 some years ago, and when I ripped it apart some moisture damage to the motherboard - in the power plug area - became evident.

Needless to say, the board was trashed then and there.

Good luck.

[PuuFa]

Thanks for the suggestion... I've had the motherboard out and I did try to look for signs of moisture damage but couldn't find any. Visually the board looks clean and good.

Some years ago I got one dead T60p with a major noodle soup damage inside and another Lenovo G550 with similar damage and both were completely revived and still working today after I soaked the motherboards in contact cleaner and replaced the keyboards. Guess I was lucky. I soaked the power plug area with contact cleaner in this T60 too, just in case, but it made no difference.

[FryPpy]

And i have exact the same thing on my T60 with X1400 couple years ago. And the solution was very simple - i have built Frankenpad But this mainboard is still with me (on shelves). It is waiting for some BIOS mod tortures;)
I have checked it and haven't found any damage in power connector area (i'll check bottom surface near power connector tomorrow). I don't remember any spilling accidents with that mainboard. But that T60 was (and is) my dailydriver - so it sustain many falls and winter journeys.

Other bad habits of that BAD mainboard.
It can charge battery even in off state. So it can startup with fully discharged battery (charge some time in off state -> disconnect AC -> start it and connect AC).
Couple of times (one time when i fully discharged battery and it abnormally powered off) it locks down completely off and only disconnecting AC + main battery + backup (yellow coin) battery can unlock it.

[4uk4a]

I'm sorry, to bring back up an old thread.
I had the same problem (T60p cpu T7400, gpu FireGL V5200), helped replacement cpu.
T60p got another cpu and works perfectly.