Hi,
What do you think this is doing? I'm really missing something here.
This is a PCIe adapter board, and the input signal is the PCIe reset.
I tried to reverse engineer based on the board:
It would make a lot of sense IF resistor R4 was populated.
But it isn't:
What's even more interesting is that this is a similar PCIe board from another vendor, and it has a same looking circuitry but doesn't even have a location for what's R4 on the first one. You can see that the collector of Q2 and the base of Q1 is directly connected without anything else. There is no via visible from the other side either.
(R5->R3; R3->R2)
Did I misidentified the transistor as 3904? (Marking 1AM?)