It actually helps a little to know that these people in Russia were asking the same question in 2005. They mention 19V, which suggests that the charger voltage appears here, as you'd expect.

Based on all input I guesstimate that it may be a PNP transistor or P Channel transistor used as a high side switch for the adaptor power input.

Emitter or Source as shown. Similar for smaller device at left.
Knowing the label or functionality of the long thin device just above the 8C6xx would be interesting ( ...7C64? - but it looks more like a crystal than a memory).

Candidates - examples only:

Bipolar

Infineon PNP Darlington BSP60 - 62. 45V+, 1A. Current too low for safety.

Better BDP954 PNP Infineon 45V+, 3A cont, 5A peak, SOT223.

MOSFET - MANY good candidates.

eg Zetex ZXMP3016GNTF6P02

6A+, 30V, SOT223-4

It actually helps a little to know that these people in Russia were asking the same question in 2005. They mention 19V, which suggests that the charger voltage appears here, as you'd expect.

Based on all input I guesstimate that it may be a PNP transistor or P Channel transistor used as a high side switch for the adaptor power input.

Emitter or Source as shown. Similar for smaller device at left.
Knowing the label or functionality of the long thin device just above the 8C6xx would be interesting ( ...7C64? - but it looks more like a crystal than a memory).

The markings in red on the diagram are my guesstimates - not based on any sure knowledge. Knowing hat voltage is measured at the points marked "+19V" would be useful.

Candidates - examples only:

Bipolar

Infineon PNP Darlington BSP60 - 62. 45V+, 1A. Current too low for safety.

Better BDP954 PNP Infineon 45V+, 3A cont, 5A peak, SOT223.

MOSFET - MANY good candidates.

eg Zetex ZXMP3016GNTF6P02

6A+, 30V, SOT223-4