Amp/Preamp Asylum

Posted by dieseldude (A) on September 11, 2024 at 14:03:21

Greetings,

I'm finally finding time to repair my Crown SA2 amp. It arrived a few years ago in multiple boxes from a chap a few miles away. It appears that the majority of issues are on the motherboard. It has many metal case dual transistors which are in various states of reformation. So I've not been able to ID them. They are branded:

ITS 31085-7913 which may be a dual npn

ITS 31120-7913 which may be a dual pnp

Both perhaps BJT's from early 79, but I'm not 100% positive. I'm going to have to find schematics as I suspect at a minimum a FET front end is lurking. Nevertheless, neither show up in my cross books so perhaps they are Crown numbers and are Intersil/Harris contract production.

Any leads would be greatly appreciated.

DD