Fender Bassman 200

[Delta362]

I'm working on a Fender Bassman 200 that had distorted output. I found some cracked solder joints on Q15 while probing the topside of the board. I also found a shorted Q10, and signs of overheating around Q10 and Q11.

Since Q10 was shorted, I'm intending to replace the MPSW92 with a ZTX757 and the MPSW42 with ZTX657. I didn't find any other shorted transistors, but given that Q10 failed, are there other transistors that I should be replacing as good practice such as replacing drivers even if they test ok when outputs fail? If so, which transistors should I also replace?

Please correct me if I'm wrong, but are the drivers Q14 and Q15, or are they Q12 and Q13, or both sets of pairs?

Thanks!

[Helmholtz]

Q14/Q15 are the drivers. Q12/Q13 are used for current limiting.

[g1]

Replacing Q10 and Q11 should be sufficient.

[Delta362]

Thank you!