Transistor Replacement

[Dreato]

I had the dim display problem recently, too. I replaced all 3 transistors (Q 2, 3 and 4) with generics: 2N3906 (I had a bunch of these) for Q 3 and 4, and MPSU56 for Q2. This last is an audio transistor I had on hand, but it worked fine.

The original Q 3 and 4 tested bad, but Q4 was fine, so I kept it in the parts box.

This leads me to a question: Generics have worked for me in many HP applications over the years. In this case, Q 3 and 4 have different parts #s. Do you think they actually have significantly different specs?

What does everyone think??