T400 takes WAY TOO LONG to turn on

[Buzon de voz]

hello group!
I have a very strange problem. Yesterday I bought a Thinkpad T400 to get spare parts, but it turns out that when testing the notebook it works perfectly, but it has a very strange problem.
When you press the power button, the computer "turns on", the cooler spins, the hard drive boots up, the notification bar lights up. But the computer doesn't give an image, it doesn't do anything at all for exactly 10 minutes.
when I say that the thinkpad do nothing, it means that the screen does not turn on, it does not respond to the keyboard, it does not give any sign that anything is happening, it seems that it is "dead". The only reason I realized it wasn't broken is because I left it plugged in and went away for a while.
After that time, the computer works perfectly, wifi, bluetooth, all the keys, the disk reader, the mouse, the screen. And the performance is exactly as expected, the computer does not suddenly shut down or crash or reboot.
The only problem is that it really takes a long time to start. And I don't know what could be the reason.
I tried touching options in the bios to see if it changed anything, but nothing. This happens before reaching the lenovo screen, literally before the computer starts, when it starts everything is perfect.

[kfzhu1229]

hello group!
I have a very strange problem. Yesterday I bought a Thinkpad T400 to get spare parts, but it turns out that when testing the notebook it works perfectly, but it has a very strange problem.
When you press the power button, the computer "turns on", the cooler spins, the hard drive boots up, the notification bar lights up. But the computer doesn't give an image, it doesn't do anything at all for exactly 10 minutes.
when I say that the thinkpad do nothing, it means that the screen does not turn on, it does not respond to the keyboard, it does not give any sign that anything is happening, it seems that it is "dead". The only reason I realized it wasn't broken is because I left it plugged in and went away for a while.
After that time, the computer works perfectly, wifi, bluetooth, all the keys, the disk reader, the mouse, the screen. And the performance is exactly as expected, the computer does not suddenly shut down or crash or reboot.
The only problem is that it really takes a long time to start. And I don't know what could be the reason.
I tried touching options in the bios to see if it changed anything, but nothing. This happens before reaching the lenovo screen, literally before the computer starts, when it starts everything is perfect.

To solve this mystery you have to learn a few more things about the behaviour of the laptop. With a known good charger and a known good battery, see if the behaviour changes when on both AC and batt, just on battery or just on charger.
If it works much better just on battery or much worse just on battery, I have a suspicion that the main 3.3V filtering cap, C216, is failing (It could also be the 5V power rail's C388 and C511, but having a cap on 3.3V rated for only 4V sound very suspicious). I've had this happen on HP laptops of the same generation where the electrolytic SMC capacitor is leaking due to high stress for running very close to its ratings the whole time.
C216 is the capacitor right beside the Ultrabay SATA Connector. You CANNOT just remove the capacitor - there are no redundancies for this capacitor, you have to replace it.

[Buzon de voz]

To solve this mystery you have to learn a few more things about the behaviour of the laptop. With a known good charger and a known good battery, see if the behaviour changes when on both AC and batt, just on battery or just on charger.
If it works much better just on battery or much worse just on battery, I have a suspicion that the main 3.3V filtering cap, C216, is failing (It could also be the 5V power rail's C388 and C511, but having a cap on 3.3V rated for only 4V sound very suspicious). I've had this happen on HP laptops of the same generation where the electrolytic SMC capacitor is leaking due to high stress for running very close to its ratings the whole time.
C216 is the capacitor right beside the Ultrabay SATA Connector. You CANNOT just remove the capacitor - there are no redundancies for this capacitor, you have to replace it.

The truth is that I have little experience handling hardware and I have no knowledge of soldering.
The notebook has a broken charging port (I already removed it, because they had destroyed it), so the only way to connect it directly to the current is through the advanced dock 2503 that I have for my main t400.
Try turning it on with only battery power, and plugged into the dock, and both simultaneously, but the standby times are the same.

[kfzhu1229]

The truth is that I have little experience handling hardware and I have no knowledge of soldering.
The notebook has a broken charging port (I already removed it, because they had destroyed it), so the only way to connect it directly to the current is through the advanced dock 2503 that I have for my main t400.
Try turning it on with only battery power, and plugged into the dock, and both simultaneously, but the standby times are the same.

Well unfortunately if it had a broken charging port and somehow 20V was sent down to the sense pin, then this motherboard might be very difficult to fix. See if for the broken charging port you have continuity from the sense pin to the main 20V pins