Nice, board missing from retroweb. 386XS build on guts of 286 design.
Its related to earlier
https://theretroweb.com/motherboards/s/ald-dat203-rev-b
https://theretroweb.com/motherboards/s/ald-dat203-rev.-c
oscillators are standard 32Khz and 14.something MHz. Transistors are either reset circuit, power good generation or battery charging.

On further investigation Q1 and Q2 are with high probability 3906 and 3904 but which is which must be researched, because on some boards the are marked in reverse Q2 and Q1.
X3 is 14.31818 Mhz and X2 is a clock oscilator of 32.768 Khz.

Need an owner of the exact board to confirm!

Just because another board used those transistors (like M396F) doesnt mean this also does. On the other hand 2N3906 and 2N3904 are what one calls jelly bean components. The most basic NPN and PNP transistors used (well, 30 years ago) in everything.
If you really dont want tracing where those are connected and what function they perform its ~moderately safe to just guess and solder randomly :] then switch around if board doesnt start.

rasz_pl wrote on 2026-05-18, 12:03:

Just because another board used those transistors (like M396F) doesnt mean this also does. On the other hand 2N3906 and 2N3904 are what one calls jelly bean components. The most basic NPN and PNP transistors used (well, 30 years ago) in everything.
If you really dont want tracing where those are connected and what function they perform its ~moderately safe to just guess and solder randomly :] then switch around if board doesnt start.

when i see EXACT same transistors on 4 different boards from this era, i think it's safe to asume that this was the standard.
I tried to power on the board without them (nothing blew in my face!) but the diag board complained about the reset circuit!

rasz_pl wrote on 2026-05-18, 12:03:

Just because another board used those transistors (like M396F) doesnt mean this also does. On the other hand 2N3906 and 2N3904 are what one calls jelly bean components. The most basic NPN and PNP transistors used (well, 30 years ago) in everything.
If you really dont want tracing where those are connected and what function they perform its ~moderately safe to just guess and solder randomly :] then switch around if board doesnt start.

For NPN/PNP - it should be relatively easy to do a couple simple measurements to figure out which one goes where - base and collector polarities are reversed between the two types.

holoprox wrote on 2026-05-23, 09:42:

when i see EXACT same transistors on 4 different boards from this era

thats what jelly bean means 😀 just like you will see LM339 or NE555 in everything. What I meant is you dont need to use _those exact transistors_ because original designer didnt really pick them specifically.

holoprox wrote on 2026-05-23, 09:42:

but the diag board complained about the reset circuit!

as was my first guess, most likely arranged as monostable multivibrator https://www.tutorialspoint.com/pulse_circuits … ltivibrator.htm Circuit that generates a pulse of fixed guaranteed width (important in case of Reset) on input pulse of varied width + will also generate said pulse on power up automagically as a side effect of its design.

TLDR: you can use any two random ordinary PNP/NPN transistors, for example seeing you are from EU you can slap BC547 (NPN) and BC557 (PNP) in there no problem.