I'm digging into a piece of HP gear, a 3466A digital multimeter, and I need to understand how I'd find a suitable replacement for a given transistor. My question is more of a "how to do this" one versus a "which part do I need in this specific case" question.
For instance, I've got a TO-92 at Q906 which has less-than-helpful silkscreen printing on it and the parts list in the schematic hasn't helped me so far. For those of you who know HP Agilent Keysight gear well, how should I decode the following line from the parts list into a real, specific transistor? Once I've got that, I know how to find a replacement (based on cross ref or just parameters):
Ref HP PN Description Mfr Mfr PN
A4Q906 1853-0016 TRANSISTOR PNP SI TO-92 PD=300MW 28480 1853-0016
Googling 1853-0016 doesn't give me anything useful and I don't want to just drop a random transistor in there. Where can I take the above info, look it up, and yield a datasheet or at least the critical parameters to then go look for a replacement transistor?