Identify SMD transistor - top marking BC RJ
Tracing the circuit, I got:-



simulate this circuit &ndash; Schematic created using CircuitLab
The biasing of Q5 suggests it is a PNP bipolar transistor. The resettable fuse rating of 0.3 A indicates that the transistor must be rated for &gt;0.3 A, and the rating of EC2 suggests a voltage rating of 16 V or higher. The package appears to be SOT89.
I did a Google image search on &quot;PNP SOT89&quot; looking for a marking code similar to &quot;BC&quot; and found an On Semi 2SB1302 with code &quot;BJ&quot;. I then searched On Semi's website for other similar transistors, and found the marking code order was the same as the listing order. This suggested that &quot;BC&quot; should correspond to 2SB1120. Finally I Googled that part number and got this:-
2SB1120