Thinkpad T43 mod. 2373: no pwr on, no LED, Vcc until TPC8014

[coindigger]

Hi specialists,
I have the above notebook here of a freind to provide some help.
The notebook is absolutely dead, no power on ist possible, no LED lights, nothing...
I checked the PS - 16.5V - fine.
I put the PS on my ear during pressing the power key - nothing changed within the PS - means no current.
I thought of a broken fuse or an open "L" in the very beginning after the power plug, thus I opened the T43.
I striped the mobo totally, just CPU and proc are still on it. The same - no power on at all.
I examined (nearly) all fuses. They count until F17. I found all except F13 and F14.
All the found ones were fine... I think there is a little hope with F13 and F14 but I doubt... Maybe somebdy could point me to these...?!
I found the voltage is going through a 4433 and through a TPC8014. Bit then it is going to a second TPC8014 and it is not released from that. The control pin of the second TPC is lost somewhere in the board...
Has anybody out here an idea where to proceed with checking?
I assumed the power on key on the keyboard could be the reason, but I was not able to check this and I don´t really focussed on that.
Thanks for any help.

Tom

[SMA]

Some of the fuse numbers aren't used.

The point between the 2 mentioned TPC8014 chips are the system DC. Voltage will come to this point from either the AC Adapter through one
of the two mosfets or from the battery through the other mosfet.

If you start your fault finding at the DC in jack and goes sideways through all the components one by one and also wants to know
where all the mosfet gate signals are comming from, then I will say that you have a long way to go.

Instead, step down to the MAX1631 and see how things are going there. Does it give out the 3.3V and 5V as it is supposed to.
Try putting your finger on the MAX1631 and see if it heats up.

You do not need the cpu and the power on switch when doing these initial power checks. The 3.3V and the 5V out of the MAX1631 is supposed
to come on as soon as the AC Adapter is connected.

And welcome to the forum.

[coindigger]

Thanks!
To observe the Maxim nearer sounds good. I will do these days. Unfortunately, I think, there are no 3.3V and 5V anywhere - at least I haven´t found them by chance.
But, I will go on reporting...

[coindigger]

Ok. Got the MAXIMs pinout and wiring at the datasheets page. Unfortunately: only V+ gets 16V, nothing else, Y6 oscillates, the package around the MAX1631 looks fine, so probably, the chip has gone dead (it´s at room temperature). As I have no donor boards anymore I feel like stopping at this point...
Tom