T23 starts only from battery, not from AC

[RealBlackStuff]

This T23 has a new motherboard, but will only boot with a main battery installed.
If any charger is connected, no go...
My T23 knowledge has become rather rusty, any suggestions?

[ajkula66]

What happens if you insert the charger once the machine has started booting?

New motherboard or not, still sounds like a board problem to me.

[rkawakami]

Going to have to agree with George on this one... sounds like the DC input circuit is toast. I'm assuming that whenever an AC adapter is plugged in, the system shuts down and no indicator lights are on, yes?

[kfzhu1229]

Also try what happens if you dock it in ThinkPad dock as charger.

[RealBlackStuff]

No luck in the dock.

I can start on battery, then put in AC, makes no difference.
But if I leave AC in and remove the battery, it immediately switches off.

Guess I'll have to measure the MOSFETs FDS6990A and replace them if needed.
I have another mobo with only 1 working RAM-slot, that I can use as donor.

[kfzhu1229]

Do you think a blown fuse is more like it?

[RealBlackStuff]

No, they're all good.

[kfzhu1229]

Then I guess take a voltmeter and see if it gets any electricity with AC adapter and also check antenna routing if you have antennas in that machine.
Let's just hope that there isn't any capacitor failure or microcracks