Dave wrote:

Last week I posted about an Emerson Research "home theatre" system that I
was given. Two 5A fuses on the CT transformer secondaries blown. This unit
has outputs for two rear speakers (L/R), a center channel (DIN connector)
and two front satellites (L/R). Now the inputs are analog RCA audio so this
box must be just simulating 5.1 using a delay or some other trickery.

What I'm looking for here is an understanding of how the various output
components interact... in particular how the NPN/PNP pairs function

I have little idea what you know and what you dont... npn/pnp pair is
your standard output pair, normally in more or less the same
configuration, but for any more details you'd need to either trace the
circuit yourself or get a cct diagram.


good except one of the a733's. My question is this: do I need to replace
BOTH a733's, i.e. to maintain matched set characteristics? I'd be looking
at an NTE290A as a replacement. Or are the c945/a733 some sort of matched
pair. I see that NTE offers either a) two matched 290A's or b) matched sets
of 289A/290A (289A is NOT listed as a replacement for 2sc945).

Little chance of needing matched pairs for anything. Transistors
distort so much they get lots of nfb applied to them, so it doesnt
matter whether theyre matched.


As I noted at the beginning, I'd like to understand which transistors drive
what if it's at all possible to determine from the information I've
provided.

not really.


NT